My mind was blown at 2:00. Yes, I am apparently an idiot, but at least I'm trying not to remain one :-). This was super helpful and to the point. Thanks!
I have 94 integra LS with a b20b 1997 crv non v tec engine. The fuel rail is AEM as well as the fuel pressure regulator. My car runs good when the vacuum hose that leads to the pressure regulator is unplugged but when I plug it again the rpm’s become weak and unsteady. After I run it for a while with the vacuum hooked up the rpm’s regulate on their own.
Some systems had other ways of adjusting that and the fpr did not have a hose. So dont freak if yours does not. For some issues or to just give the car a bit of zip, one could up the fp a few psi. Fpr were on both electronic systems and mechanical fi systems.
great video, but I have a doubt, how does the engine respond with a shorter vacuum hose or a longer vacuum hose? any impact on the engine respond? any advice or suggestion is highly appreciated. Thanks.
Good question! A really long hose could potentially have a negative effect, but its small and unlikely unless someone really wanted an excessively long hose
So if you keep the vacuum line off and plug it will it make more pressure or less because I have a more high performance motor and I need a little extra pressure to my fuel rail and when I plugged the vacuum connector on the regulator it seemed to run better
I've been having problems with a GM 350 Ramjet crate engine installed in my 58 Apache. The thing is sluggish on acceleration and uphill. I scanned the engine using ScannerPro and found out the manifold pressure was too high under load and the spark advance was too high. I figured it was a vacuum leak and the base timing was off. I searched for a leak and the base timing was just fine. So, where do I go? I just put a pressure gauge on the EFI rail and found out the fuel pressure dropped from 39psi to about 35/36psi at cruising rpm (2000). Now that i watched this video, it makes sense now, the fuel pressure differential at high vacuum (lower psi on the rail) causes the engine to be sluggish on acceleration. The problem may not be the pressure regulator. But I darned sure understand the problem now. That will make it much easier to diagnose.
Hi, thanks for that. I have a question. My Australian 4.0 Ltr 1995 Falcon has a failed regulator, and they are no longer available, even aftermarket. It's rated at 270kpa. It seems a Suzuki and Ford Laser/fiesta are also 270kpa and have same fitment to fuel rail and vacuum. It's just a different connection for the tank return. Easy modification. Question is, should this work fine, or is there something other than 270kpa that I need to watch out for (eg: as these are smaller capacity engines)? Thanks in advance.
So the hose to the intake manifold connected to the regulator I’m guessing so that I’m not an idiot is a constant vacuum so that the vacuum decreases as I smash the throttle
Im sorry but when you connect the FPR to your engine you shouldnt connect the vaccuum line (yet) because you wouldnt be able to tell the actual fuel pressure coming from the pump if the manifold vaccuum is meddling with the fuel pressure when idling. So first you hook it up, check and set the pressure without the vacuum hose and THEN you connect the hose for a proper working FPR. Right?
See no reply. To bad that is a question I have. With the Vacuum line closed off 0 vacuum, that would be close to WOT. That would be where the most fuel is needed to reach the target A/F. At least that is how I see it. If you set the called for psi at idle when pressure drops the psi would go too high? Right. This is a NA engine.
Nice video, question, so I have just got a car, and the vacuum hose from the manifold isn't connected to the fuel regulator, and the that small connection on the fuel regulator leaks small amounts of fuel, it also sits at 50psi all the time. The car runs rich and can't hold a steady idle until it's warm. I assume the regulator is busted as fuel shouldn't come from that side connection and will need replacing, at which point I can connect the manifold vacuum tube and that should remedy in some way the rich running? Am I on the right track? This is my first car that I'm tinkering with so it's a steep learning curve!
HELP PLEASE. 1995 pontiac grand prix gtp 3.4 engine I changed fuel pressure regulator car will not start. I have no.idea where vacuum hose goes. So my question is if that tiny hose not connected car will not start? I get nothing when engine cranks no backfire nothing just cranks. Ty
Ok stupid question, I have an ls intake for a 4.8, the intake does not have the fuel pressure regulator nipple on it can I t into the nipple that the pcv valve comes off of?
my car will not run at all itll start and idle insanely bad for a few minutes then come outta it some times but something ive noticed is when it does run it misfires and has very poor throttle response pump works fine but there is no gas coming outta the return line so could it be its not getting enough vacuum or its just comepletely locked up or something ive bought a new regulator fingers crossed this is it ive also changed the filter to no avail
Well if I say a fuel pressure regulator job is to keep a constant pressure difference between the fuel pressure and the intake manifold pressure then it will be correct. Having it set to 50 PSI fuel pressure, and when the intake manifold pressure goes to 20 PSI, the regulator will let the fuel pressure reach 70 PSI ?
@@EFIU_Ben when the manifold pressure drop it means more air had entered... so the fuel need to add more pressure to meet the requirements for mixture??? did i get it right?
If you don’t have or lose vacuum to the regulator would that let the engine crank and start but die immediately after? My engine will crank and start but dies immediately but I lost vacuum with the line.
Hmmm ok so I have a cammed 5.3 swapped into my Hyundai and when I do key on engine off fpr goes to 60 then right to zero and sometimes to start the car I have to do key on engine off twice then crank for it to start. Should I hook the vacuum line up to the fpr from the manifold even tho the cars not boosted or do I have another problem..
I get F1007 and F1014 codes still searching what they mean. Somebody suggesting it may be crankshaft or timing issue, maybe crankshaft sensor, but I doubt car could be out of timing as it was not opened. Someone suggesting it’s a fuel problem perhaps too much fuel. It’s a Peugeot 207, any idea where to start?
Curently working on an NB miata The fuel pressure regulator is situated in the tank, and not connected to MAP It's suposed to regulate to a constant 3 bar The car had trouble starting, took a long time to start, then was running but really low on power... I've changed the pump because I suspected either the fuel regulator or the pump to be bad... The new pump is a high flow pump, not OE one . I was unable to find a fuel regulator (for a decent price that is, cause OEM part is almost worth the price of a decent aftermarket adjustable fuel regulator) The car now runs great, but I find the pump is a bit noisy (maybe because I didn't put panel and insulation back) I wonder if the pressure regulator is fine, or the new pump might just be sending enough pressure to compensate for a bad regulator, and will die soon if I keep runing it like that. My main questioning is, can I delete the OEM regulator and replace it with an aftermarket one, that would rather be in the engine bay, or next to the fuel tank (but not in)? If so should I run it to MAP (car is N/A but might be supercharged later so then obviously)? I don't know how the factory ECU works with the fuel pump but it feels like it's simply regulating pressure/flow by RPM thus increasing voltage output at the alternator and consequently at the pump... If I put a variable fuel regulator, I don't know how it would react...
Nice, brilliant technical introduction to differential fuel pressure and how it relates to dynamic engine loads 🙌🏼 This is a fundamental concept and your delivery was spot on for all levels 👌🏻 P.S. Love the engine simulator and gold box being used for your flow bench rig, would have been even better to see what fuel flow meter you were using 😊
If I have a slightly bigger fuel pump than stock, something like a 255... Would that make my stock fuel injectors leak... And if the answer is yes, could a fuel pressure regulator correct this problem...
solid video really explains a lot. I am building a 1992 Celica with a Turbo charged 5SFE engine, i'm going to be using a Haltech elite 1500 to run it with 550cc injectors, walbro 255lph pump. Should be i looking at an AFPR too or will i be able to program this variable through Elite 1500?
Not sure if you found your answer. You will need higher rated injectors so 1) they’re not running as hard and 2) they’re actually pushing out enough fuel to combust in the amount of air being supplied. Just limiting the fuel pressure will only make it either idle rough or stall
I have a volkswagen polo 1.4 year 2000 the engine light warns me of code17559 does this include the fuel regulator i have change everything else in that code
I need to replace my fuel filter in my Polo. I have two options: one without an integrated pressure regulator (cheaper) and one with. Which one should I buy?
I think it depends on the car. Mine is between the fuel pump and rail (mounted in the engine bay). At prime (ignition on) it maintains pressure on the rail for starting. This is a returnless system though.
Ok good. I needed that. Today I found a teeny tiny vacuum line cracked on my gmc 5.3 that was sucking air. Trying to figure out it’s purpose. I finally got to understanding it to be the fuel pressure regulator vacuum line. So next I wanted to know if it mattered, that’s how I ended up here. Thanks. I will tape it up to repairs the crack for now, and replace it when I find a hose.
With all due respect, you have created a misconception; see beginning around 1:13: the pump sends fuel to the rail (not the regulator) and the regulator (at the end of the rail) regulates the pressure of the fuel inside the rail and if needed releases excess fuel via a return line to the fuel tank.
fuel pressure regulator BEFORE or AFTER the fuel rail?? i thought the injectors need a specific fuel pressure to work properly, therefore the fuel pressure regulator (fpr). Now I was told that you should install the fpr after the fuel rail....that would put as much pressure on the injectors as my fuel pump can do - which in most cases is way too much??
What is not discussed as this does not apply to direct-injected engines. You leave that barb wide open, open to atmosphere that is. The commanded high pressure fuel pump controlled by the ECU will adjust the fuel pressure.
does the fuel regulator need hold pressure at prime to 40+psi and suppose to hold at 40+psi ? or is it ok to go to 0psi after prime but no full ignition - is this a cause of a leak down bad regulator not holding pressure before ignition
I still don't understand why the fuel pressure regulator is connected to the intake manifold by the vacuum line... there's a pressure sensor in the intake manifold, couldn't the ecu just read that and tell the fuel pressure regulator what to do? Or is it the case here that the fuel pressure regulator determines the pressure by itself via the vacuum line without any input from the ecu?
@@turboroman The FPR is a valve, those can be electronically controlled easily enough. The ECU controls plenty of other things this way. Kind of like how some EGR valves are opened via a vacuum diaphragm, and some are fully electronic. I'm curious as to why they don't use the electronic method here.
@@PeterB12345 they just used the so far much more common type of FPR. I know about the modern electronic ones. But this video covers the "analog" type. The vacuum reference port is there to keep the differential pressure constant during all engine load conditions.
@@turboroman Thanks for that, I didn't know there were fully electric ones. I was just wondering about the design choice when so many other things seem to be electric. I guess that's kind of a trend then... "Let the intake manifold vacuum actuate it" is turning into let the ECU control it via sensor input. But this is happening over time, not all at once.
My guess is the injector nozzle.. they probably test and select nozzle design to optimize atomization at a given pressure differential between manifold pressure to fuel pressure..
Do a plug test! I just found out that method and was blown away, now just have to get a few sets of plugs An some hacksaw blades I plan on doing this on my 90 celica I've got a new set of injectors from 210cc to 220cc on stock engine management :( running super rich so hopefully this will be my answer to finding a little bit better tuneability with future na modifications
Do all engines require manifold pressure compensation? I have a naturally aspirated, throttle body injected engine and have always run the compensation port on the regulator open to atmosphere. My FP regulator is installed on the return line to the tank, not on the pressure line from the pump. With oxygen sensor in the exhaust controlling AF ratio, how would manifold pressure compensation help me?
im confused about this one too... i have m52 engine and im doing ccv delete and i have no clue if i can run the fpr open or not because currently its connected to my ccv not directly to intake manifold.
Hello from Argentina! Great video! Just to check if I got it right. FPR is not there to assure constant pressure on the fuel rail but to assure you have a constant dP across the injector (between intake manifold and fuel rail). I assume that's because when you get an injector, the flow spec (let's say 250cc/min) is given at a constant dP (let's say 3 bar) and if for example in the case the throttle is closed you'll get a higher dp and that means higher fuel flow on the same injection time. Please say I'm right up to now. So.. I first want to say that I'm really new on EFI, I'm trying to learn to convert an old carburator car and I know I can really sound like an idiot with my question.. but what I don't understand and I would really appreciate your comments is what about the regulator without the vacum/boost port? is there any way to compensate with tunning? For ex on the same case I comented above (closed throttle) lowering injection time? Thanks in advance!
The old D Jetronic Mercedes use a fuel pressure regulator without a vacuum boost port. In this case, the FPR is designed to keep the pressure constant at 2 bar. There is however the crucial MAP (maximum absolute pressure sensor) which senses manifold vacuum and feeds this info back to the ECU which in turn tells the injectors when the fire. Mike
If your a high HP application this set up will destroy your motor…. FPR after the fuel rails. The fuel pump should be supplying straight to the rails.. then be regulated after
Neat clip but fails to address NA applications. Not everything has a supercharger or turbo, what about NA applications? Is vacuum reference still required or not needed? Seems odd to leave NA applications out of the discussion entirely
Shouldn't the title be "Understanding how a Boost reference fuel pressure regulator works". A real explanation of how the regulator works would be talking about the valve and spring that help regulate pressure.
So just to sound like an idiot... Your video actually told me what a fuel pressure regulator's job is and what it does but not , you know... How it works. Please correct me if im wrong i am learning this stuff as fast as TH-cam can teach me
Depends on if your pcm is set for vacuum/boost reference in the injector flow table to wether you connect the vacuum line or not
My mind was blown at 2:00. Yes, I am apparently an idiot, but at least I'm trying not to remain one :-). This was super helpful and to the point. Thanks!
So... Relatively speaking it does keep the fuel pressure constant, as a function of the manifold air pressure variable? Loving these videos so much.
Yes but only the correct amount lol
I have 94 integra LS with a b20b 1997 crv non v tec engine. The fuel rail is AEM as well as the fuel pressure regulator. My car runs good when the vacuum hose that leads to the pressure regulator is unplugged but when I plug it again the rpm’s become weak and unsteady. After I run it for a while with the vacuum hooked up the rpm’s regulate on their own.
Some systems had other ways of adjusting that and the fpr did not have a hose. So dont freak if yours does not. For some issues or to just give the car a bit of zip, one could up the fp a few psi. Fpr were on both electronic systems and mechanical fi systems.
eg D Jetronic Mercs dont have vacuum hose on the FPR.
Studying for the army’s asvab auto&shop portion of the test. This helps me put what I read into pictures. ❤
None of this was on the asvab for me (airforce btw)
great video, but I have a doubt, how does the engine respond with a shorter vacuum hose or a longer vacuum hose? any impact on the engine respond? any advice or suggestion is highly appreciated. Thanks.
Good question! A really long hose could potentially have a negative effect, but its small and unlikely unless someone really wanted an excessively long hose
So if you keep the vacuum line off and plug it will it make more pressure or less because I have a more high performance motor and I need a little extra pressure to my fuel rail and when I plugged the vacuum connector on the regulator it seemed to run better
I've been having problems with a GM 350 Ramjet crate engine installed in my 58 Apache. The thing is sluggish on acceleration and uphill. I scanned the engine using ScannerPro and found out the manifold pressure was too high under load and the spark advance was too high.
I figured it was a vacuum leak and the base timing was off. I searched for a leak and the base timing was just fine. So, where do I go?
I just put a pressure gauge on the EFI rail and found out the fuel pressure dropped from 39psi to about 35/36psi at cruising rpm (2000).
Now that i watched this video, it makes sense now, the fuel pressure differential at high vacuum (lower psi on the rail) causes the engine to be sluggish on acceleration.
The problem may not be the pressure regulator. But I darned sure understand the problem now. That will make it much easier to diagnose.
Got a new subscriber as soon as you mentioned the title. I need this, quick and to the point, How not to be an idiot.
Hi, thanks for that. I have a question. My Australian 4.0 Ltr 1995 Falcon has a failed regulator, and they are no longer available, even aftermarket. It's rated at 270kpa. It seems a Suzuki and Ford Laser/fiesta are also 270kpa and have same fitment to fuel rail and vacuum. It's just a different connection for the tank return. Easy modification. Question is, should this work fine, or is there something other than 270kpa that I need to watch out for (eg: as these are smaller capacity engines)? Thanks in advance.
So the hose to the intake manifold connected to the regulator I’m guessing so that I’m not an idiot is a constant vacuum so that the vacuum decreases as I smash the throttle
Im sorry but when you connect the FPR to your engine you shouldnt connect the vaccuum line (yet) because you wouldnt be able to tell the actual fuel pressure coming from the pump if the manifold vaccuum is meddling with the fuel pressure when idling. So first you hook it up, check and set the pressure without the vacuum hose and THEN you connect the hose for a proper working FPR.
Right?
See no reply. To bad that is a question I have. With the Vacuum line closed off 0 vacuum, that would be close to WOT. That would be where the most fuel is needed to reach the target A/F. At least that is how I see it. If you set the called for psi at idle when pressure drops the psi would go too high? Right. This is a NA engine.
can you show it in/on the vehicle instead of the bench mockup?
Heres a good explanation of what's happening directly on the car in terms of pressures th-cam.com/video/qO8z8cpp77g/w-d-xo.html
Nice video, question, so I have just got a car, and the vacuum hose from the manifold isn't connected to the fuel regulator, and the that small connection on the fuel regulator leaks small amounts of fuel, it also sits at 50psi all the time. The car runs rich and can't hold a steady idle until it's warm. I assume the regulator is busted as fuel shouldn't come from that side connection and will need replacing, at which point I can connect the manifold vacuum tube and that should remedy in some way the rich running? Am I on the right track? This is my first car that I'm tinkering with so it's a steep learning curve!
HELP PLEASE. 1995 pontiac grand prix gtp 3.4 engine
I changed fuel pressure regulator car will not start. I have no.idea where vacuum hose goes. So my question is if that tiny hose not connected car will not start? I get nothing when engine cranks no backfire nothing just cranks. Ty
So what should the PSI read on the FPR for my TBI at idle on my 1995 GMC K-1500 with 5.7 Litre?
Is the vacuum connection also necessary for carburetor applications?
I once saw somebody installing this in a diesel om606 engin what’s the use since you don’t have any vacuum
Hello,I want to ask can we install feul regulator for diesel engine
This was great. Thank you. Much informtive, very help.
Nice work, one question, is there fuel pressure regulator for turbo aplication only? or all the same to non and with turbo aplication?
Does the same rule apply with a carburetor? Do I run a line from the regulator to the intake? I was curious where that went coming off the regulator
Ok stupid question, I have an ls intake for a 4.8, the intake does not have the fuel pressure regulator nipple on it can I t into the nipple that the pcv valve comes off of?
Dumb Question: I only have a carburetor, no ECM or any type of boost.
Still connect hose to intake manifold?
my car will not run at all itll start and idle insanely bad for a few minutes then come outta it some times but something ive noticed is when it does run it misfires and has very poor throttle response pump works fine but there is no gas coming outta the return line so could it be its not getting enough vacuum or its just comepletely locked up or something ive bought a new regulator fingers crossed this is it ive also changed the filter to no avail
Well if I say a fuel pressure regulator job is to keep a constant pressure difference between the fuel pressure and the intake manifold pressure then it will be correct.
Having it set to 50 PSI fuel pressure, and when the intake manifold pressure goes to 20 PSI, the regulator will let the fuel pressure reach 70 PSI ?
correct
@@EFIU_Ben
when the manifold pressure drop it means more air had entered...
so the fuel need to add more pressure to meet the requirements for mixture???
did i get it right?
If you don’t have or lose vacuum to the regulator would that let the engine crank and start but die immediately after?
My engine will crank and start but dies immediately but I lost vacuum with the line.
Thank you please show more when it's working on the test bench
Why does some vehicles have a solenoid in between the manifold intake and fuel pressure regulator?
This excellent video definitely helped my idiot-itis symptoms!
If u have fuel in the hose between the intake manifold and FPR does that mean FPR is bad
Hmmm ok so I have a cammed 5.3 swapped into my Hyundai and when I do key on engine off fpr goes to 60 then right to zero and sometimes to start the car I have to do key on engine off twice then crank for it to start. Should I hook the vacuum line up to the fpr from the manifold even tho the cars not boosted or do I have another problem..
sounds like a different issue with the fuel returning back to the tank with no check valve...
@ I will purchase another adjustable fuel pressure regular thank you
I get F1007 and F1014 codes still searching what they mean. Somebody suggesting it may be crankshaft or timing issue, maybe crankshaft sensor, but I doubt car could be out of timing as it was not opened. Someone suggesting it’s a fuel problem perhaps too much fuel. It’s a Peugeot 207, any idea where to start?
Curently working on an NB miata
The fuel pressure regulator is situated in the tank, and not connected to MAP
It's suposed to regulate to a constant 3 bar
The car had trouble starting, took a long time to start, then was running but really low on power...
I've changed the pump because I suspected either the fuel regulator or the pump to be bad...
The new pump is a high flow pump, not OE one .
I was unable to find a fuel regulator (for a decent price that is, cause OEM part is almost worth the price of a decent aftermarket adjustable fuel regulator)
The car now runs great, but I find the pump is a bit noisy (maybe because I didn't put panel and insulation back)
I wonder if the pressure regulator is fine, or the new pump might just be sending enough pressure to compensate for a bad regulator, and will die soon if I keep runing it like that.
My main questioning is, can I delete the OEM regulator and replace it with an aftermarket one, that would rather be in the engine bay, or next to the fuel tank (but not in)?
If so should I run it to MAP (car is N/A but might be supercharged later so then obviously)?
I don't know how the factory ECU works with the fuel pump but it feels like it's simply regulating pressure/flow by RPM thus increasing voltage output at the alternator and consequently at the pump...
If I put a variable fuel regulator, I don't know how it would react...
Already set my base fuel pressure. Do I need to hook up boost reference vacuum, if I'm N/A.?
yes!
Wait, how come in my car the FPR is located passed the fuel injectors? 1991 Honda accord
Nice, brilliant technical introduction to differential fuel pressure and how it relates to dynamic engine loads 🙌🏼 This is a fundamental concept and your delivery was spot on for all levels 👌🏻
P.S. Love the engine simulator and gold box being used for your flow bench rig, would have been even better to see what fuel flow meter you were using 😊
Short and informative. Thats how we like it. Great ideer 👍😉
Does fuel run through the top portion of the regulator? Mine has a pin hole in the top. Debating on hooking it up or getting another
If I have a slightly bigger fuel pump than stock, something like a 255...
Would that make my stock fuel injectors leak...
And if the answer is yes, could a fuel pressure regulator correct this problem...
solid video really explains a lot. I am building a 1992 Celica with a Turbo charged 5SFE engine, i'm going to be using a Haltech elite 1500 to run it with 550cc injectors, walbro 255lph pump. Should be i looking at an AFPR too or will i be able to program this variable through Elite 1500?
So, in boosted applications, would you need higher rated fuel injectors? Or does the fpr compensating fuel pressure completely solve the issue?
Not sure if you found your answer. You will need higher rated injectors so 1) they’re not running as hard and 2) they’re actually pushing out enough fuel to combust in the amount of air being supplied. Just limiting the fuel pressure will only make it either idle rough or stall
I have a volkswagen polo 1.4 year 2000 the engine light warns me of code17559 does this include the fuel regulator i have change everything else in that code
I need to replace my fuel filter in my Polo. I have two options: one without an integrated pressure regulator (cheaper) and one with. Which one should I buy?
They both do the same thing just get the one with out it’s just a basic filter it’ll do you fine
Whats a fuelplumb?
Haha :)
No seriously good video... looking forward to the next one
It is what you make of it ;)
Can anyone help the original mercedes e190 w201 is crazy money can I use anything else
How does this differ in a DI car?
I thought the FPR should be mounted after the fuel rail, not before it (as you have it).
I think it depends on the car. Mine is between the fuel pump and rail (mounted in the engine bay). At prime (ignition on) it maintains pressure on the rail for starting.
This is a returnless system though.
Ok good. I needed that. Today I found a teeny tiny vacuum line cracked on my gmc 5.3 that was sucking air. Trying to figure out it’s purpose. I finally got to understanding it to be the fuel pressure regulator vacuum line. So next I wanted to know if it mattered, that’s how I ended up here. Thanks. I will tape it up to repairs the crack for now, and replace it when I find a hose.
Is it the same for a carbureted engine as it is for one with injectors ?
carbureted doesnt need one cuz it only need a fuel pump just to fill up tha carb but not needing much pressure to supply
With all due respect, you have created a misconception; see beginning around 1:13: the pump sends fuel to the rail (not the regulator) and the regulator (at the end of the rail) regulates the pressure of the fuel inside the rail and if needed releases excess fuel via a return line to the fuel tank.
fuel pressure regulator BEFORE or AFTER the fuel rail??
i thought the injectors need a specific fuel pressure to work properly, therefore the fuel pressure regulator (fpr). Now I was told that you should install the fpr after the fuel rail....that would put as much pressure on the injectors as my fuel pump can do - which in most cases is way too much??
they really need to be specific...
cuz diff engine size requires diff amount of supply in an specific pressure...
Here's a good explanation of different setups - skip to 6 : 23 th-cam.com/video/qO8z8cpp77g/w-d-xo.html
What is not discussed as this does not apply to direct-injected engines. You leave that barb wide open, open to atmosphere that is. The commanded high pressure fuel pump controlled by the ECU will adjust the fuel pressure.
does the fuel regulator need hold pressure at prime to 40+psi and suppose to hold at 40+psi ? or is it ok to go to 0psi after prime but no full ignition - is this a cause of a leak down bad regulator not holding pressure before ignition
I still don't understand why the fuel pressure regulator is connected to the intake manifold by the vacuum line... there's a pressure sensor in the intake manifold, couldn't the ecu just read that and tell the fuel pressure regulator what to do? Or is it the case here that the fuel pressure regulator determines the pressure by itself via the vacuum line without any input from the ecu?
Do you think the ECU has an auxiliary mouth in the engine bay to tell the FPR what to do?
@@turboroman The FPR is a valve, those can be electronically controlled easily enough. The ECU controls plenty of other things this way. Kind of like how some EGR valves are opened via a vacuum diaphragm, and some are fully electronic. I'm curious as to why they don't use the electronic method here.
@@PeterB12345 they just used the so far much more common type of FPR. I know about the modern electronic ones. But this video covers the "analog" type. The vacuum reference port is there to keep the differential pressure constant during all engine load conditions.
@@turboroman Thanks for that, I didn't know there were fully electric ones. I was just wondering about the design choice when so many other things seem to be electric. I guess that's kind of a trend then... "Let the intake manifold vacuum actuate it" is turning into let the ECU control it via sensor input. But this is happening over time, not all at once.
My guess is the injector nozzle.. they probably test and select nozzle design to optimize atomization at a given pressure differential between manifold pressure to fuel pressure..
Do you recommend a fuel pressure regulator on every engine?
I'm planning to install one on my motorcycle. But I don't see if it would benefit.
Do a plug test! I just found out that method and was blown away, now just have to get a few sets of plugs An some hacksaw blades I plan on doing this on my 90 celica I've got a new set of injectors from 210cc to 220cc on stock engine management :( running super rich so hopefully this will be my answer to finding a little bit better tuneability with future na modifications
Well ok. How does it work with a carbonater. Not everyone has fuel ejection.
Great explanation, your the man
Is this only for EFI
Finally explained ! big thanks
Do all engines require manifold pressure compensation? I have a naturally aspirated, throttle body injected engine and have always run the compensation port on the regulator open to atmosphere. My FP regulator is installed on the return line to the tank, not on the pressure line from the pump. With oxygen sensor in the exhaust controlling AF ratio, how would manifold pressure compensation help me?
Boosted yes. NA not always, depending on the ECU. LS engines from the factory just run straight pressure.
im confused about this one too... i have m52 engine and im doing ccv delete and i have no clue if i can run the fpr open or not because currently its connected to my ccv not directly to intake manifold.
What if you dont have an intake manifold?
Im not sure what are u talking here unless it is a coal powered car, 😂
@@makaupurple8242 1960s engine. No computer parts not sensors. No eca map. Just need an inline fuel regulator
Nice sweet explanation.
very good video my brother ..you would be a excellent instructor...i would definitely sign up for your class..
This helped. Thank you
Great Job..Ty.
Hello from Argentina! Great video!
Just to check if I got it right. FPR is not there to assure constant pressure on the fuel rail but to assure you have a constant dP across the injector (between intake manifold and fuel rail).
I assume that's because when you get an injector, the flow spec (let's say 250cc/min) is given at a constant dP (let's say 3 bar) and if for example in the case the throttle is closed you'll get a higher dp and that means higher fuel flow on the same injection time.
Please say I'm right up to now.
So.. I first want to say that I'm really new on EFI, I'm trying to learn to convert an old carburator car and I know I can really sound like an idiot with my question.. but what I don't understand and I would really appreciate your comments is what about the regulator without the vacum/boost port? is there any way to compensate with tunning? For ex on the same case I comented above (closed throttle) lowering injection time?
Thanks in advance!
The old D Jetronic Mercedes use a fuel pressure regulator without a vacuum boost port. In this case, the FPR is designed to keep the pressure constant at 2 bar. There is however the crucial MAP (maximum absolute pressure sensor) which senses manifold vacuum and feeds this info back to the ECU which in turn tells the injectors when the fire. Mike
If your a high HP application this set up will destroy your motor…. FPR after the fuel rails. The fuel pump should be supplying straight to the rails.. then be regulated after
Neat clip but fails to address NA applications. Not everything has a supercharger or turbo, what about NA applications? Is vacuum reference still required or not needed? Seems odd to leave NA applications out of the discussion entirely
Do OEM manufactures compensate via ECM instead?
many of them do!
Oh !!! this is vocabulary lessons.
Weird though, because on a K20A engine swap it doesn't like having that vacuum connected; throws everything off so we just leave it off.
I didn’t get it. I thought i knew about fuel, now im scratching my head
Same here. The explanation is bad so that it is not understandable, at least for me.
It provides relative constant pressure.
thank you
I feel not so dumb now. Thanks EFI. Me no dumb dumb no more.
How come nobody explains where the fuel goes in/out on the regulator?
It varies depending on the system used.
Yeah cause I have qft and it has no inlet/outlet direction also has the manifold tube spot
Thought he was going to show some examples instead of talking about it
How not to be an idiot. I dig it
Finally! thanks a lot!
Thanks very helpful
Shouldn't the title be "Understanding how a Boost reference fuel pressure regulator works". A real explanation of how the regulator works would be talking about the valve and spring that help regulate pressure.
That part is common knowledge
NO ONE,
NO QUESTION IS DUMB!!!
If I put 50 pounds of boost to my engine it will blow up🤣🤣🤣
The fuel plump.
So just to sound like an idiot... Your video actually told me what a fuel pressure regulator's job is and what it does but not , you know... How it works. Please correct me if im wrong i am learning this stuff as fast as TH-cam can teach me
I dont have a fuel plump
“Fuel Plump”
Come on guys this is simple
Lol lol lol lol lol !!!!! Yo, did he jus say “ how not to be a nigga” 0:23 ? Lol lol lol lol !!!!!
Liked just for aesthetics alone
no pressure
And this only applies to returnless Fuel system in boosted engines
im confused... can i run my m52 engine without the fpr connected to intake manifold?
Just make a bloody diagram.
Excellent! Now has anyone directed you to any videos of how not to come across as a smug arrogant douchebag
Love the WRONG! Followed by something that isn't true all the time.
This is negative and pretentious
well this was a waste of time