I believe the reason you have worse performance at idle is because the regulator is open at idle, allowing bleedoff back to the tank. The regulator closes as the throttle plate opens and engine vacuum decreases. The regulator doesn't monitor actual fuel pressure. It's just calibrated to dump a certain amount of fuel back to the tank for a given amount of engine vacuum.
@@SchrodingersBox That's a serious complement coming from you. I've been pretty busy at work and haven't had a chance to check out the QM site. I'm looking forward to it though. I should have more time once the weather cools down.
This is a great follow-up to the last series on running a business; the tips on how customer methodology plays out worked really well. One of the great benefits of following this channel is its holistic approach to learning - so much of its older content can be referenced (and revisited) in newer videos, such as the analogy of liquid versus electricity from the Basic Electrical series. This channel just goes from strength to strength. 👏👏👏 🤣[Having said that, I thought this particular diagnosis took forever! I could tell it was a bad fuel pump right off the bat. And I wasn't even watching the video properly, but I could hear it from my lawn chair. I was drinking a lemonade and I knew straight away: fuel pump.]🤣 (I guess Matt is not the only guy who can reference older videos.) 👍
I was going to suggest pinching off the return line, Matt. Glad I waited to further in the video. It's only because I remember the procedure from Eric O.
Great video! One thing I want to mention about the misfires not counting is that these older Fords have to run a crank relearn before it will count misfires. If it had a dead battery it likely cleared the Keep Alive Memory. There should be a data PID that will say "Misfire Profile Correction Learned" with either a yes or no. It will eventually learn on it's own but the quickest way is to drive the car up to 60 mph then coast down to 40 a couple of times. Newer Fords you can do the crank learn with a scan tool.
Seems like it has more of a ruptured fuel line in the tank after the pump. I always like to dead head the pump and the engage it and listen at the tank for a running fuel inside.
A pump that has a good strong motor but the actual pump section sux badly would not change it's sound so much when deadheaded. The test you describe would also only work with a rather empty tank and as you well know customers only bring in cars with bad fuel pumps when the tank is full.🤣
That happened very recently to my father's 99 Grand Marquis. The hose between the pump and the metal line that's part of the fuel pump/sending unit assembly had a rupture. The fuel pump was pretty loud and had an extended crank time especially when cold. My guess is the lower pressure caused the pump to spin faster making it louder.
check this when you have tge pump out. i have a 96 k1500, i was loosing fuel pressure when tge truck shut off. I thought it was the fuel pump check valve, after checking the regulator and injectors for leaking. I replaced the pump and same thing. Then i heard a hissing sound at 1/4 tank of fuel. so i again pulled the tank and checked the pump. what it turned out to be is there is a thick peice of special rubber line between the pump and the hard metal line inside the tank. i flexed the small rubber line and saw a pin hole blown in it.
Perhaps I don't understand this particular system, but by clamping the return line I believe you are not taking the fuel pump check valve out of the equation, as said. Rather, you are stopping flow back to tank via the regulator (as I understand it the return line is after the regulator and fuel rail) ... However, what this did show was that by stopping flow to the tank via the regulator, you still lost pressure via the pump check valve (or possibly via injectors), all of which are pressurised while pump is deadheaded. To confirm it is the pump check valve, you would have to clamp the line before the fuel rail but after the gauge. To isolate injectors, add a clamp after the regulator, ie at the return line and move the other clamp before the gauge while system is pressurised. Am I wrong???
the check valve is in the tank after the regulator so clamping the line does remove it as a factor. when I did this, static pressure no longer dropped. this means the leak has to be AFTER the regulator. therefore there are no leaks into the engine- the leak must be inside the fuel tank itself.
@@SchrodingersBox I agree with the logic … but I believed the check valve purpose was to stop bleed back thru the pump on the fuel inlet line b4 the rail. My understanding was it was the regulators job to stop bleed back at engine off by shutting due to zero manifold vacuum. If check valve is on return side that would affect my test methods: but if it is what stops bleed back on pump side?? You’ve prompted me to go and do some system revision research
Ohhhhhhh. yeah you may be right about that!!! i follow what you are saying. i do believe on this model it’s on return line. and it has to be because the pressure held. unless somehow clamping the return line somehow kicked the check valve on feed line into action? hmmm I don’t know.
@@SchrodingersBox For sure, there are always variations and I make the mistake of falling into an assumption at times. I'm coincidentally trying to pinpoint the cause of an intermittent long'ish crank on a 1990 Miata. Like you, I just refuse to throw a part (ie pump} at it. I want to pinpint whether the issue is the Regulator, the Injector/s, or the pump/check valve, which is most likely. Because it's intermittent, I've only seen the gauge plummet to zero after turn-off twice. But every time I put a gauge on it when i'm ready to clamp things up, everything holds pressure beauitifully. Never had that happen when you're chasing an intermittent?? Yeah right!
At 21:20 did you mean bank 1 sensor 2? What am I missing? At 23:44 you pulled another one but you corrected it later. The only reason I'm nit picking is because it took me a stupid amount of time to figure out things like -trim=adding or taking away fuel vs. +trim or higher graph on an O2 meant rich or lean and if I'm not alone then it could add to the confusion for someone else. Thank you for doing what you do.
I wouldn't rule out a "vacuum leak". With a car that old you may have a stuck open EGR valve. Wouldn't be too noticeable at full throttle but definitely noticed at idle and would act like a vacuum leak. But you're still seeing a little smoke. Heating up the engine can help seal it and smooth out idle. An idle air control circuit can also mess with things, but couldn't tell if you had the AC on. I'm going with the EGR valve as a major contributing factor. And yes, that's my final answer. :-)
Yes totally correct but remember the smoke test was done on a cold engine and was negative. but indeed this is the exact reason I always get baseline fuel trim data. if replacing the pump only brings the fuel trims down 50% then I absolutely would revisit vacuum leak- or other things like MAF. but if fuel trims zero, I know I am done and the truck won’t come back.
@@SchrodingersBox I was tweaking my answer while you replied. Agreed.. re-view my better worded/rearranged answer. I also wanted to add... with a vehicle that old, is crimping down a rubber hose for fuel a wise option? I would worry about it cracking. I would like to see what your alternative methods of plugging a return hose are. Could you cover that? And would your stopping that hose rule out a failure in the fuel pressure regulator? Doesn't it use that return hose as well? Agreed on the fuel pump - it was weak. [late edit - pulling a vacuum on the EGR valve should kill the engine - you're opening it, as if under high RPM's, but since it's dying under idle anyway, I'm thinking you won't see much worse of a drop in performance with vacuum pulled on it. So long since I dealt with EGR issues. Sorry for the late edits.]
Had a older Chevy that sat around that acted like that and it ended up being the short rubber hose right off the fuel pump inside the tank was leaking wonder if this will be the same
Great job, and advice for business. These old Fords can be nightmarish if the battery was dead and wiped codes and it was trying to relearn the faults. If I may, what Autel scanner is that sir? Stay safe and God bless
Thanks for watching. the scanner used in this video is an Autel MS909. it was given to me by Autel in exchange for making some training content for their on-board video help on their scanners.
@Schrodingers Box That's outstanding! Are you happy with its capabilities, overall would you recommend it? I need a new scanner and I'm about cross-eyed from reading reviews.
I'm assuming you clamped the fuel return line after the regulator, before it dumps back in the tank. If so, clamping the line here did not isolate the pump's check valve - it isolated/dead-headed the pressure regulator. The fact that the rapid pressure decay stopped after clamping this line, would mean that the fuel regulator valve was stuck open (this is the path that you manually blocked.) To test the check valve, you would have had to pressurize the system, and then clamp the fuel supply line between the check valve and the fuel rail (with the gauge installed on the fuel rail.) I agree the pump was bad due to low dead-head pressure with the return line blocked, but I suspect issues with the regulator based on the decay test. What am I missing?
yep everything you said is correct. the line was clamped on a rubber portion after the regulator- regulator is on the rail. yes it’s possible the regulator could have an issue still- I won’t know until proper fuel pressure is restored however a faulty regulator would just dump fuel to the return line- so with it clamped, the regulator actually becomes irrelevant with the clamp test.
PRODIGY Schrodingers Box Thank you very much for sharing what you know with us great tutorial video Brilliant PRODIGY Schrodingers box From Nick Ayivor from London England UK 🇬🇧
I believe the reason you have worse performance at idle is because the regulator is open at idle, allowing bleedoff back to the tank. The regulator closes as the throttle plate opens and engine vacuum decreases. The regulator doesn't monitor actual fuel pressure. It's just calibrated to dump a certain amount of fuel back to the tank for a given amount of engine vacuum.
Great thought- that totally makes sense. Always appreciate your input- you're a smart dude!!
@@SchrodingersBox That's a serious complement coming from you. I've been pretty busy at work and haven't had a chance to check out the QM site. I'm looking forward to it though. I should have more time once the weather cools down.
The regulators are notorious for leaking on these too. Pull the vacuum hose off if it has fuel in it, it's cooked.
This is a great follow-up to the last series on running a business; the tips on how customer methodology plays out worked really well. One of the great benefits of following this channel is its holistic approach to learning - so much of its older content can be referenced (and revisited) in newer videos, such as the analogy of liquid versus electricity from the Basic Electrical series. This channel just goes from strength to strength. 👏👏👏
🤣[Having said that, I thought this particular diagnosis took forever! I could tell it was a bad fuel pump right off the bat. And I wasn't even watching the video properly, but I could hear it from my lawn chair. I was drinking a lemonade and I knew straight away: fuel pump.]🤣
(I guess Matt is not the only guy who can reference older videos.)
👍
Hahahahaha. Awesome internal joke!!!
@@SchrodingersBox Yes, I thought you'd like that one. LMAO!
I was going to suggest pinching off the return line, Matt. Glad I waited to further in the video.
It's only because I remember the procedure from Eric O.
Great video! One thing I want to mention about the misfires not counting is that these older Fords have to run a crank relearn before it will count misfires. If it had a dead battery it likely cleared the Keep Alive Memory. There should be a data PID that will say "Misfire Profile Correction Learned" with either a yes or no. It will eventually learn on it's own but the quickest way is to drive the car up to 60 mph then coast down to 40 a couple of times. Newer Fords you can do the crank learn with a scan tool.
Ah brilliant!! That totally explains it!!
Lol....I love the way crack on the trolls Matt. "Uh.he's not going to use his thousand dollar scan tool" 😄
Got to see 20% out of range before tripping a fault code condition. This is why I think newer cars are coming out with fuel pressure sensors
Seems like it has more of a ruptured fuel line in the tank after the pump. I always like to dead head the pump and the engage it and listen at the tank for a running fuel inside.
yes it did look like that. i dropped the tank today and removed the pump and it was intact though.
A pump that has a good strong motor but the actual pump section sux badly would not change it's sound so much when deadheaded. The test you describe would also only work with a rather empty tank and as you well know customers only bring in cars with bad fuel pumps when the tank is full.🤣
@@InsideOfMyOwnMind Truth
That happened very recently to my father's 99 Grand Marquis. The hose between the pump and the metal line that's part of the fuel pump/sending unit assembly had a rupture. The fuel pump was pretty loud and had an extended crank time especially when cold. My guess is the lower pressure caused the pump to spin faster making it louder.
check this when you have tge pump out.
i have a 96 k1500, i was loosing fuel pressure when tge truck shut off. I thought it was the fuel pump check valve, after checking the regulator and injectors for leaking. I replaced the pump and same thing. Then i heard a hissing sound at 1/4 tank of fuel. so i again pulled the tank and checked the pump. what it turned out to be is there is a thick peice of special rubber line between the pump and the hard metal line inside the tank. i flexed the small rubber line and saw a pin hole blown in it.
Thanks
Informative as always. Can you please give some kind of part number for that clip you use to keep the power probe in constant on? Thank you.
Yeah I don’t have the part number- I just found it on power probes website. You can also just use a book binder clamp.
Very interesting
Have you ever used the calculated load value to check for Mass Airflow problems?
Yes I have. I will need to do a video on "volumetric efficiency calculations"!!
What was the fix for this truck? Did a fuel pump fix the idle issue?
Perhaps I don't understand this particular system, but by clamping the return line I believe you are not taking the fuel pump check valve out of the equation, as said. Rather, you are stopping flow back to tank via the regulator (as I understand it the return line is after the regulator and fuel rail) ... However, what this did show was that by stopping flow to the tank via the regulator, you still lost pressure via the pump check valve (or possibly via injectors), all of which are pressurised while pump is deadheaded. To confirm it is the pump check valve, you would have to clamp the line before the fuel rail but after the gauge. To isolate injectors, add a clamp after the regulator, ie at the return line and move the other clamp before the gauge while system is pressurised. Am I wrong???
the check valve is in the tank after the regulator so clamping the line does remove it as a factor. when I did this, static pressure no longer dropped. this means the leak has to be AFTER the regulator. therefore there are no leaks into the engine- the leak must be inside the fuel tank itself.
@@SchrodingersBox I agree with the logic … but I believed the check valve purpose was to stop bleed back thru the pump on the fuel inlet line b4 the rail. My understanding was it was the regulators job to stop bleed back at engine off by shutting due to zero manifold vacuum. If check valve is on return side that would affect my test methods: but if it is what stops bleed back on pump side?? You’ve prompted me to go and do some system revision research
Ohhhhhhh. yeah you may be right about that!!! i follow what you are saying. i do believe on this model it’s on return line. and it has to be because the pressure held. unless somehow clamping the return line somehow kicked the check valve on feed line into action? hmmm I don’t know.
@@SchrodingersBox For sure, there are always variations and I make the mistake of falling into an assumption at times. I'm coincidentally trying to pinpoint the cause of an intermittent long'ish crank on a 1990 Miata. Like you, I just refuse to throw a part (ie pump} at it. I want to pinpint whether the issue is the Regulator, the Injector/s, or the pump/check valve, which is most likely. Because it's intermittent, I've only seen the gauge plummet to zero after turn-off twice. But every time I put a gauge on it when i'm ready to clamp things up, everything holds pressure beauitifully. Never had that happen when you're chasing an intermittent?? Yeah right!
At 21:20 did you mean bank 1 sensor 2? What am I missing?
At 23:44 you pulled another one but you corrected it later.
The only reason I'm nit picking is because it took me a stupid amount of time to figure out things like -trim=adding or taking away fuel vs. +trim or higher graph on an O2 meant rich or lean and if I'm not alone then it could add to the confusion for someone else.
Thank you for doing what you do.
Dang nice catch- yes I did misspeak. bank 1 sensor 2 is what I meant and as you can see the catalyst activity is good.
I wouldn't rule out a "vacuum leak". With a car that old you may have a stuck open EGR valve. Wouldn't be too noticeable at full throttle but definitely noticed at idle and would act like a vacuum leak. But you're still seeing a little smoke. Heating up the engine can help seal it and smooth out idle. An idle air control circuit can also mess with things, but couldn't tell if you had the AC on. I'm going with the EGR valve as a major contributing factor. And yes, that's my final answer. :-)
Yes totally correct but remember the smoke test was done on a cold engine and was negative. but indeed this is the exact reason I always get baseline fuel trim data. if replacing the pump only brings the fuel trims down 50% then I absolutely would revisit vacuum leak- or other things like MAF. but if fuel trims zero, I know I am done and the truck won’t come back.
@@SchrodingersBox I was tweaking my answer while you replied. Agreed.. re-view my better worded/rearranged answer. I also wanted to add... with a vehicle that old, is crimping down a rubber hose for fuel a wise option? I would worry about it cracking. I would like to see what your alternative methods of plugging a return hose are. Could you cover that? And would your stopping that hose rule out a failure in the fuel pressure regulator? Doesn't it use that return hose as well? Agreed on the fuel pump - it was weak. [late edit - pulling a vacuum on the EGR valve should kill the engine - you're opening it, as if under high RPM's, but since it's dying under idle anyway, I'm thinking you won't see much worse of a drop in performance with vacuum pulled on it. So long since I dealt with EGR issues. Sorry for the late edits.]
@@jum5238 I have a 96 4.0L Explorer (same truck pretty much). EGR valves can leak externally thru the pintle valve shaft! I had that issue.
Had a older Chevy that sat around that acted like that and it ended up being the short rubber hose right off the fuel pump inside the tank was leaking wonder if this will be the same
Yea someone else mentioned this too. i did remove the pump today and the internal hoses were intact.
@@SchrodingersBox Always enjoy the videos and always learn something
Thank you
Great job, and advice for business. These old Fords can be nightmarish if the battery was dead and wiped codes and it was trying to relearn the faults. If I may, what Autel scanner is that sir? Stay safe and God bless
Thanks for watching. the scanner used in this video is an Autel MS909. it was given to me by Autel in exchange for making some training content for their on-board video help on their scanners.
@Schrodingers Box That's outstanding! Are you happy with its capabilities, overall would you recommend it? I need a new scanner and I'm about cross-eyed from reading reviews.
Totally happy with it.
Resistance is only a factor when you have flow... Like a swollen prostate...
Hahahaha great analogy!!!
I'm assuming you clamped the fuel return line after the regulator, before it dumps back in the tank. If so, clamping the line here did not isolate the pump's check valve - it isolated/dead-headed the pressure regulator. The fact that the rapid pressure decay stopped after clamping this line, would mean that the fuel regulator valve was stuck open (this is the path that you manually blocked.) To test the check valve, you would have had to pressurize the system, and then clamp the fuel supply line between the check valve and the fuel rail (with the gauge installed on the fuel rail.)
I agree the pump was bad due to low dead-head pressure with the return line blocked, but I suspect issues with the regulator based on the decay test. What am I missing?
yep everything you said is correct. the line was clamped on a rubber portion after the regulator- regulator is on the rail. yes it’s possible the regulator could have an issue still- I won’t know until proper fuel pressure is restored however a faulty regulator would just dump fuel to the return line- so with it clamped, the regulator actually becomes irrelevant with the clamp test.
Would videos be available for download if I subscribed to QM?
No, sorry but I do not allow downloading of videos to protect the material.
Which Autel are you using?
It’s an MS909. Autel is letting me use it to produce videos for them.
@@SchrodingersBox Are you liking it’s features?
PRODIGY Schrodingers Box
Thank you very much for sharing what you know with us great tutorial video Brilliant
PRODIGY Schrodingers box
From Nick Ayivor from London England UK 🇬🇧
Much appreciated as always!!
8 sparkies and 4 cylinders... Ford whattya smokin?
It's actually a Mazda motor