GM Fuel Pump Relay Testing
ฝัง
- เผยแพร่เมื่อ 26 ส.ค. 2024
- The vehicle being tested is a 1999 Chevy Suburban with no fuel pressure. This truck had a new fuel pump installed and still did not have fuel pressure. In this video I will show you how to troubleshoot this entire fuel pump electrical system, including the fuel pump relay, wiring and computer.
Engine Performance Diagnostics chapter 3 page 26
Symptoms
- no start with good spark
- no fuel pressure
- no trouble codes
Fix
- repair wiring to the fuel (new pump was wired backwards
Tests shown
- how to test a fuel pump relay in a power distribution box.
- power side switched circuit design description and operation.
- Fuel pump power and ground testing.
- how to manually jump a fuel pump from the fuse box
- how to test a fuel pump relay
- relay pins (what each one does and how to test them)
- how to verify computer control of the fuel pump relay
- bias voltage (what is it, how to use it, how it can cause misdiagnosis when using a voltmeter)
- wiring diagram review of a fuel pump relay circuit in my classroom (a ScannerDanner premium segment)
- how to measure fuel pump current
- what sets a fuel pump relay control trouble code
Tools used
- ATD Tools 5519 Auto Ranging Digital Multimeter
www.jbtoolsale...
- incandescent test light www.jbtoolsale...
- backprobing pins AES' Electronics Accupuncture Probes www.aeswave.com...
Playlist
- (Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing
• (Chapters 14, 15,16) F...
Related videos
- Fuel Pump Electrical Circuits Description and Operation
• Fuel Pump Electrical C...
- Fuel Pump Relay Problem
• Fuel Pump Relay Problem
- How to test and fix a PGM-FI main relay on a Honda, Acura
• How to test and fix a ...
- How to test an electric fuel pump (1997 4.3L Chevy Blazer CPI)
• Fuel psi less than 50 ...
- Fuel pump electrical circuit diagnosis (no fuel pressure testing) GM
• Fuel pump electrical c...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdan... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.
![How To Test and Diagnose Relays and Wiring [4 & 5 Pin]](http://i.ytimg.com/vi/S-DwV0HLsE4/mqdefault.jpg)
![How To Test and Diagnose Relays and Wiring [4 & 5 Pin]](/img/tr.png)
You answered my question before I could ask and yes I'm subscribed to SD prienun . Learning your insight and methods I was instantly going to say, would it light a 2 ohm bulb if you found 12v on an unkugged sensor. No it would not. Anyone watching Paul's free vids, do yourself a favor and subscribe. He's just teasing you with the free ones and giving you insight. The forum is amazing, the new video player is awesome and Paul does respond to any questions . Best money I spend every month even though I've completed the course. Always something new and always there for a refresher. Oh and keep his book In your toolbox!
Thank you so much for this comment my friend and for your long time support
sinking or open collector transistor. Used widely in industrial control, jumped the fence at GM and invaded our cars when computers became standard. Coil load tells the computer there is a load there. When the transistor is told to turn on by the computer it SINKS to ground and loads up passing voltage! The test light acts as he said just as the relay coil would. 42 years of electrical and the last 16 in training others one of the best descriptions of sinking and open collector I ever saw. Awesome!
+John Goodman thanks for the comment! Feel free to keep going! I've never heard the terms "sinking or open collector". I only know this from a mechanic standpoint. If I could clone myself, I would go back to school for electronic engineering. Love hearing from guys like you
I took 3 years of automotive classes in high school. I now sit in front of a monitor 10 hours a
day for a living but never lost my love in fixing cars. This one of the best or the best instructional
video on one topic. It's direct and no nonsense instructions and disruptive background music.
Excellent continuing education program.
Great example of why when diagnosing an electrical issue a test light and a meter should be used when trouble shooting.
Thanks for the video,very informative!
The Oil pressure sensor is also a source of power for the fuel pump, while the engine is running. This is done to keep you going in case of a fuel pump relay failure, once you turn the engine off, no oil pressure, no power to the fuel pump from that source!
If theres an issue with the fuel pump like maybe a short is there the possibility of the oil pressure gauge reading near max? Ive heard that extra “symptom “ with a fuel pump problem
Curious at this point if that union would shut off the fuel pump if the ecm read no oil pressure coming from the oil pressure sensor. Thinking im gonna test that theory. Pull the oil pressure sensor and ground on engine and plug the hole. See if vehicle runs
@@pitchforkpeasant6219how did it go? I’m having the same issue
2004 GMC Savana 3500 cutaway, with a 15' box. No start, no pressure. Was able to jump the correct pins (you explained very well) and send constant power to the pump to investigate further. Found out to be a bad connection w/ the connector at the pump. Would have never stumbled across it without your information. Was sending it to the shop tomorrow....Great work and fantastic information!
Poor guy had no business rewiring the pump. We have a saying in the Electrical trade that comes to mind. It goes like this: "1 wire hook up, 2 wire f*** up, 3 wire drag up!" Awesome job Scanner Danner.
thank you so much! what a great comment. this bias voltage is cool when you know how to use it. it is a major time saver for troubleshooting wiring problems for sure. nice to know that you appreciate the material
Paul, I've immersed myself in *your videos cam/crank sensors, Hall effect pull up/dn testing, mostly in troubleshooting an 01 I30 no start for weeks and you've impressed me to no end. But **this lesson here has inspired me so much so that I *had to write to commend you on your style, brilliance, tenacity and skill! Even more thank you for your technique in imparting knowledge to the layman now so rarely found I'm sure. I'm an FAA Certificated Airframe & Powerplant Mechanic since 16 years old (63 now,) Commercial Pilot and Instructor since 1974 and tow truck driver shade tree automotive wrench too, admittedly **not even close to your realm - Learjets vs. Maserati = two different beasts. But where does one start explaining your passion? Brilliant teaching technique? Abundant resource of the mind? Vast stores of vital bits of info that just... I mean... and you produce smooth relevant attractive media seeming to come from out of nowhere like this: Pwd Side Circ Bias Vltg and backprobing IR drop right **there in the trenches with simple test light and VOM!!!??? And for free???!! I mean you are so cool - meticulous white board drawings, manuals books, well I just wanted to say thank you for being so kind to us out here. Your students I hope will be touching my vehicles out here and you've restored my confidence raising my opinion of auto wrenches in general. I hope they appreciate your stern yet friendly demeanor, temperance, ethical mentorship and carry your legacy paying it forward and so on for quite some time. There will never be another sage like you, and at such a young age. Amazing. Thank you! Paul The Pilot, San Diego
Thanks for the reply! I asked my mechanic; The dist cap and ignition components have been checked, its all good. The whole distributor is 18 months old. The fuel pressure is 57 both when cranking and idling. The fuel pump has unusual sound, wich changes when banging on the tank.
Great job on describing the bias voltage! You took something that could be extremely confusing and made it fairly simple.
Thank you!
Great video! I am an electrical engineer and you explained the bias circuit well. I think you can say the 12 volts is across the high ohm internal resistor and your test light has very little resistance and can not create an voltage drop (no load). That's why you see zero volts with the test light. Freaking outstanding explanation of the fuel pump circuit!
This is what real troubleshooting looks like! Great job!
The effort you put in to this video and your teaching skills are amazing. Thank you very much for doing this.
You know bud there can be to top lefts etc. Who's view? Where you standing? A fukd mess off the git.
Awesome!!!!! I have been in the automotive repair industry since 1983 as a tech and as an instructor, you did a very good explanation of the bias voltage.
Thank you John!
ScannerDanner
ScannerDanner
Thabk you Idaho
I h axes ve been working with this shocks since 2008 or 9
GOT TO SAY YOU ARE A GREAT TEACHER AND I HOPE YOUR STUDENTS ARE VERY HAPPY HAVING YOU THERE WITH THEM GOOD LUCK AND GOD BLESS YOU !!!
ScannerDanner is the Master of Electrical Circuits, Wow! keep these case studys coming!
Fantastic troubleshooting! I’m pretty sure It’s going to fix my problem where the previous owner bypassed the relay to make a pump run continuously Instead of diagnosing
Who is this guy!? Great instructor and definitely a passionate person. Thanks Scanner Dan, you saved me some money on my diagnostic and I learned something really cool.
Thanks so much! My name is Paul Danner and I am an instructor at Rosedale Technical College in Pittsburgh PA
ScannerDanner help please
Your a good teacher,you get off teaching,if one would listen to your video 10 times it would just click just like that little piece of plastic your working on when you turn on the key a flow of electric current reaches
Transistor and it clicks, sending that current in a controlled flo To open the pump which pumps
Fuel to whatever system
You have.
Having the test light and/or the current meter connected are great tools working together when locating an intermittent pump or current feed problem. I connected a set up like that and monitored them while driving an E350 6.8L V10. The problem was the fused power pin at the Inertia Switch had got hot, lost it's spring integrity, which caused it to lose contact with the Inertia switch. Replaced the pigtail, problem solved. Another tech had replaced the fuel pump AND the fuel pump relay. He didn't know the connector at the Inertia Switch had got hot/overheated. It took a while, I finally found it. Problem solved.
Good Video! Didn't know about the bias voltage in that GM circuit.
@contagiousFX The pump circuit was wired backwards so this just causes the electric motor to spin in reverse. This caused a low amperage no psi condition. The other two wires were computer sensor wires that do not carry any measurable amount of current and would just cause full to be empty and empty to be full on the gauge. Funny thing is half tank would have been accurate.
A great teacher, reminds me of my school boy days at Denver Automotive and Diesel College, I am old school. Thanks Dan! keep on teaching the youngers.
Many of the GM's had a red wire (usually located in the proximity of the fuel line quick connectors) that connects to the normally closed contact of the fuel pump relay that can be used to power the fuel pump directly, with key off engine not running. Known as the fuel pump priming connector. Handy for pumping skankey fuel out of the tank, testing the fuel pump itself, etc.
Of course you know I am going to say yes. But I think you will find that after you have it you will want to buy a scope simply because of how accurate you can be with one. I do teach other methods of testing (DMM, test lights, Scanner etc.) IT is not all scope stuff and you certainly don't need a Verus to do what I am doing. I think you will agree though that alot of the stuff I am doing you couldn't do without a scope.
After starting your course I figured save up for a picoscipe which I would love. You explain a scope in so much detail that I went with a Hantek and uscope. I figure use the things while I save and I'm glad I did . The experience is the most important part!
@PUNTO8SERVICE thank you so much for your kind words. and may God bless you too!
I thank God and Your Video,My c2500 suburban 7.4 2wd runs again,I too who does his own repairs was trying to consider a local shop!
great video I have messed that up a bunch of times test light is only way to check them I finally bought tge Lesley relay extentions do all my testing with them very handy
Outstanding video, my 99 Suburban wouldn't start after a long drive. It finally started but I'm going to do the checks thanks to your video. Much appreciated.
Thank You for your time in instructing us on how to diagnose a fuel problem !!
What a great video and great explanation. Having some electrical background helps too. It definitely helps why one reads voltage during troubleshooting when you wouldn't expect to.
This is why I have Scanner Danner premium on his website. Even if he never makes another video, how can u thank him for the humongous library chocked full of instructional material. I have watched this video several times. But now I have an 01 GMC 4.8 in the shop. And that bias voltage will help me identify control pins. GM relays will plug in both ways and that throws me off. Thank u Paul!!
Bill Rimmer
Even if they plug in both ways it's still the same in the box. ...
This guy is good. he is very informative even when its technical, I somehow understood even when Im just laymen. I open this video because my hyundai starex 1999 wont start and I suspected on fuel pump failure cause I run low on diesel the other night. Im changing my glow plugs first since I did not have the pressure of my fuel pump tested yet.. I had a good education here. Hope we'll have more of this helpful videos. Kudos. God bless you.
Thanks for this video. I'm just a home wrench turner. I've run into this situation before and have in the past preferred to use my volt meter over a test light for this sort of thing. Now I understand some limitations I did not understand previously. Thumbs up!!!
ScannerDanner, thanks for a GREAT video! I appreciate the detailed explanations and diagrams. I work in the medical device field as an Electronic Tech and I've been doing my own auto electrical for 3+ decades, but I still learn new things from your videos that have puzzled me. Looking forward to getting your book.
Thanks so much!
Pay attention this is a mechanic at work he is a maestro he is a professional
Yes, we just moved from Homestead to Crafton. We never closed down
Thanks!
Unless I sent the information to the wrong Scanner Danner on messenger after I downloaded the messenger you did not respond. Need to know if the test I did shows that I need a new fuel pump. I purchased one this morning. Cost me $71. Don't want to drop the tank if it isn't necessary. Please respond. Thank you.
@@michaelpearce8661 I don't use Messenger for ScannerDanner, but I do with my personal account Paul Danner
@@ScannerDanner you had asked me if I was on Facebook and you seemed to want me to go to messenger to discuss the fuel pump issue I was having. I downloaded messenger and sent some pictures. Does that mean you didn't get anything?
Because I had no ground and two hots with the key on. I believe that the fuel pump has shorted out but hate to drop the fuel tank if I don't need to. Got two offers for doing the repair. $399 estimated and $130/hr. refused to give estimate without seeing vehicle.
Do I look you up under your name on messenger to send you the pictures?
@@michaelpearce8661 I did not get anything as I said, I do not use Messenger for ScannerDanner but I do for my personal account. Just send me a friend request on facebook and once I accept it, then you'll be able to send me stuff via messenger. OR we can just continue here.
I appreciate the attention to detail and troubleshooting analysis. I'll definitely be checking out more of your videos.
Great video. I like the comment on the lean pop through the intake at snap throttle. I have been using these videos to troubleshoot electric fuel pumps measuring current and the armature waveforms. These videos have been very useful. Thanks.
Genius, this guy SHOULD be an engineer designing this stuff. Seems more intelligent then me and most of the people I went to school with for mechanical engineering.
Thanks man, I'm just a guy who barely passed high school and didn't figure out that I was functional until I got to electrical and electronic classes in tech school 😄
Life's been different ever since
And the Oscar go's to, Scannerdanner !! For best supporting instructor! Now I get it, I needed that visual. Lol that Buick cooling fan relay has been haunting me. I can see now threw this vid where I was getting confused.. Thanks Dan for breaking it down..
High praise for this video! Danner is thorough and provides all the necessary background to understand what's going on. Great diagnostic technique. Very professional! Thanks.
I like that idea. they also sell relay testing adapters that come in a kit that I have my eye on
I'm Learning So Much from
This guy I just Need Tools
To Get Me Started on Working
On My Own Car. Thanks for
All The Good Knowledge☺
We bought our truck used and have this exact wiring mess. Thank you so much for this video brother. It helped and helped a lot!
Thanks for the help. changed fuel pump, strainer, and fuel filter. starts right up every time!!!!!!
yes, do what you said you haven't done yet. Check your power and ground at the pump with the relay jumped.
I have seen a jump start do the trick. I have another video on this system where I show the tests you need to do. Search "fuel pressure" or GM cpi
I have a '94 silverado I have to work on sunday apparently they changed a dead battery and i no gas since. I checked it out a while back and pump isn't kicking on. I was almost ready to change pump till I saw the work involved. probably the pump but good to test power first for sure. Wasn't sure where the relay was..till now..very thorough video my man! thanks
@Bonfield2002 lol thanks, they take care of me. And thank you for the feedback, I'm glad it made sense.
The bias voltage used on power side switched outputs (some) can be used to cut diagnostic time down to a fraction of what the flow charts will have you do for opens and shorts in a control wire. The key though is knowing about it and how to use it to your advantage. Of course as I described in the video it can get you in trouble too.
you saved my butt showing bias voltage . I was making check on my 1998 5.7 vortec and showed 12.24 v. this was messing with my head and i was thing something else was wrong.... I had watch someone else on this relay and they said no voltage on that pin with key off.....thanks so much.
Nice! So many people have no clue it is even there.
Que buen diagnostico, es impresionante lo que usted hace con los vehículos. Felicitaciones.
awsome video sir i have never messed much with electricty but watching this video Inspired me to try to { tackle my no power to the fuel pump relay wire } on my car!!
you need more guidance we can help you on my forum www.scannerdanner.com, it is free to join, hope to see you there!
I'm not sure you can bypass this type of system without some type of add-on electronic unit. They use a resistor that is built into a hall-effect switch that is part of the lock cylinder. The re-learn on these was to simply leave the key on for 10 minutes (until the security light stops flashing) and possibly repeat the procedure.
I'm hoping that will fix my problem on my 1999 Chevy Suburban. Everything worked fine until I pulled the trouble codes with my scanner and cleared them. Now the fuel pump won't kick in and I followed your video to the T. This is exactly what is happening. I'm hoping the 10 minute relearn will work. Thank you for the great video.
I encountered an infant warmer that would not power up. Several biomedical equipment techs at the hospital called me in as they were unable to figure this out. There was full output voltage out from the transformers secondary, and on the circuit board test points, YET NO AMPERAGE. I actually tied the secondary wires together and plugged it into the 110 and the transformer didnt even get warm, much less blow. It was EXACTLY the same scenario that the bias circuit yields.
Moral of your story---The VOM has hi impedence (resistance) as not to affect the circuitry it is testing.
You should teach so the tech work wont blow your back out!!
Dan, you are awesome! Excellent teacher. I have fixed two of my Chevy truck's watching your videos and felt confident because it makes sense in my mind. Thank you so much!
Thank you! My name is Paul Danner btw 😉
"I don't make the circuits"... more like you explain em' priceless thank you for your talents!
Glad you like them!
@@ScannerDanner Nice to see quality product and someone who KNOWS what they are talking about!! Thank you again!
How do I trigger fuel pump
Yes, your fuel psi is to low during cranking. This system needs to be higher than 50 psi to start. Spec is at least 60 during a crank. When the fuel pump gets weak on this design system, this is the exact symptom. The weak pump with only 10-11 volts (system voltage during a crank) cannot produce enough psi, but with 14 volts (running voltage) it can.
Wow... You guys deserve medals for your painstaking film!
I still don't quite understand why the PCM needs that bias voltage - which makes a 1950 test-light superior to a modern, 10-MegOhm meter - but that discovery at the back reinforces what I tell people about using OLD shops instead of start-ups...
I actually encountered the same problem with 110V in my Elks club. When I converted old-style potentiometers and mag-ballasts to modern electronic units, they wouldn't dim... Sure enough, some moron had wired white-to-black & black-to white!
LOL
Wtf Happened ..
Wtf Happened Bias often is needed to hold transistor on or off in ecu circuit and other electronics. Gets complex in solid state boards.
I have been caught out using a multi meter in the first part of the video. Excellent explanation as usual Paul!
it was only my 1990 MH barina, aka suzuki swift, picked it up from a mate for $100. i was more worried about the branding of a paper clip shape singed into my fingers. PS ETCG got me onto watching your videos dan and im now a big fan. youre an excellent teacher and video maker- keep up the fight mate
I cut one relay open and made it into a manual push button to 86 and 85 with a micro switch for testing
I am sorry you feel this way. There is one thing I need to clarify and I should have but didn't in the video. We placed our t-pins between the terminal and the plastic housing NOT in the female part of the terminal. As for the wires that were damaged under the vehicle, they were like that when we got it. I understand you not liking piercing a wire to do a test but sometimes it is necessary. Hopefully you will give me another chance to see that I am not a hack. Either way, Have a great day.
Hey Guys, this is my 3rd or 4th time coming to this site for help on different issues with my 1999 GMC Suburban. I love my GM vehicles and have had a great run of luck buying older used vehicles (Chevy, GM, GMC, and so on) and this site has been invaluable to me in regards to fixing my cars, with both time and money. THE ONE MAJOR PROBLEM I HAVE HAD IS WITH THE DEALER AND HIS MECHANIC. I WILL REFRAIN MYSELF FROM PUTTING IN ANY DERROGATORY REMARKS AT THIS POINT IN TIME. HOWEVER, IF I DO FIND OUT THAT THIS DEALER IS AND HIS MECHANIC HAVE BEEN DOING SOMETHING TO FORCE ME TO GO BACK TO HIM FOR WHAT I CALL REPEAT REPAIRS, I WILL WASTE NO TIME IN LETTING YOU GUYS KNOW ABOUT HIS OPERATION. I WILL NOT WASTE ANY TIME IN INFORMING YOU ABOUT THESE GUYS. I WILL GO THIS FAR AND TELL YOU THAT THIS GUY IS LOCATED ON THE ATTLEBORO / NORTON LINE.
OH YEAH, WHILE I HAVE YOUR ATTENTION, I FEEL IT IS MY DUTY TO ALSO INFORM YOU GUYS THAT obama IS NOT ONLY TRYING TO TAKE AWAY OUR GUN RIGHTS HE IS ALSO NOW TRYING TO GO FURTHER BY TRYING TO USE HIS EXECUTIVE POWERS TO SCREW WITH OUR INTERNET USAGE, SO GUYS IF WE DON'T DO SOMETHING ABOUT THIS IDIOT WE'RE THE ONLY ONES THAT WILL HAVE SOMETHING TO LOSE HERE. I ALSO JUST SAW SOMETHING ABOUT HIM WHERE HE HAS BEEN GIVING MORE MONEY TO MORE ILLEGAL ALIENS AND IF I CAN FIND OUT WHERE THAT INFO WENT I WILL MOST CERTAINLY BRING IT TO YOUR ATTENTION SO THAT WE ALL ARE AWARE AS TO WHAT HE IS DOING TO US. GOOD LUCK AND GOD BLESS TO YOU ALL.
how about those black boxes there putting in every car starting in 2015 to track and tax by the mile.INFOWARSdotCOM
Dude you carry one in your pocket. It's called your phone
Connect your light to pin 85, turn the key off and wait 5 seconds or so, then turn the key back on (don't crank it). Let me know if the light, lights up for a second or two.
I very much appreciate this video! Although it wasn't the issue I was experiencing at the time (fuel pump working intermittently), it did get my brain gears in motion. I had removed the bed to change rear cab corners, and had just loosely placed the ground bolt back in place, that just happened to ground the bed lights AND the fuel pump. After finding no continuity between the pump lead ground and the frame, the a-ha moment smacked me like a freight train. A very good feeling freight train :) Subbed, and thanks for the content!
awesome and great find by you, good job and thanks for the sub!
Because the amperage was very low (around 2 amps), a plugged filter causing no fuel pressure at all would have caused very high amps. Also from my experience if you have a fuel filter that is plugged so bad as to cause a 0 fuel pressure reading, that filter has already ruined the fuel pump. So you put a pump and filter in it. Of course you could always replace the filter and re-test if you desire.
for sure and the heat you felt was from a resistance problem. a melted connector would be next if you didn't correct the issue.
Danner, You just made my day with that biased voltage explanation. Awhile ago i was working on a relay circuit and my voltmeter "found" this and it threw me for hours. Nobody
I talked to ever had an answer. Like a Christmas present LOL Thanks. Hope Santa brings you one of those Lisle relay test jumper kits. The dink that stabbed, cut and miss wired that pump should get coal.
@ScannerDanner The best parts of your vids are the ability to explain a function exactly although you do need some basic understanding to absorb it. The bias voltage on the control side of the relay "clicked" only after you explained its function as sensing wire to indicate a fault and turn on a MIL. I hope they are paying you well because your earning every cent. Well done !!!
At 12.40 you say pin 86. I think you mean pin 85. I am working on this same fuse box. Pin 30 melted, so someone wired in an external relay. I have no voltage at pin 85. I do have signal when cranking. The pump is always running when relay is plugged in. That says 30 and 87 are wired so the relay leaves this thing running.
Thank you for posting this. Bias voltage who would have known. Helped me out a lot. Still not receiving the correct voltage from the PCM. Off to figure that one out.
@Bonfield2002 Did the bias voltage part make sense? Was it clear enough? It was certainly difficult to explain.
Ok. I'll try the jump start and see how that works. i need to get a fuel pressure gage anyway in case something like this happens again. Appreciate your info and help. Thank you
Wow... this is a phenomenal video, with a very thorough explanation. I always wondered how GM and Chrysler could monitor Relay circuits and throw a P1XXX code for a relay coil (control) failure. Im sure other manuf. do as well, Ive only seen it on GM and Chrysler. Thank you very much for this video. I don't use a test light as often as I probably should, usually use a DMM. I'll have to pull out the test light more often.
OMG, I've been scratching my head on this for ever!!!! Thanks.
Nice! Light bulb moment then?
EXCELLENT JOB !!! great teacher -- well spoken -- complete
thank you Steve
I have been learning so much from people's hands-on videos.Thanks for letting us pic ur brain.
Thank you you don't know how much you help me right now to learn how to figure this out I really appreciate it fella
Thanks ScannerDanner ! I am really enjoying and learning much from your straight forward videos.
WOW!! Just learned a WHOLE bunch of excellent info. watching your awesomely produced video! Just a fantastic job on every level! Thank YOU!!
See of it starts when you spray carb clean in the intake, if it does then it could be the pump.if it doesn't then check it for spark next.
hello ok so when you spray starter fluid in intake and test start ive seen you need to remove relay first! is this so??
thanks for confirming those ground wire
If there is a return line, pinch it off and check pump max psi next. (should be near 100) Then if it stays at 50, check your power and ground.
It is called a smartboard.
If you want to learn more about what I am doing you should get me eBook. Go to my channel page for the website listing, or it is embedded in all of my videos. (Auto Computers Troubleshooting)
Your diagram makes it pretty clear. Ideally you could measure the voltage across the coil in the relay to see if its being energized. Once you unplug the relay the 100K pullup resistor is in series with your meter ( say a MegOhm or more) so most of the 12 volts drops across your meter. I suppose you could unplug the relay and put a test resistor (of similar resistance to the coil in the relay) where the coil would be, and measure across that.
this video , saved my but , helped me determine, i didnt have a ground . it would be better if he took out all the diagrams/graph part , but all in , need to add , a reminder if you took the bed off a pickup for installation of pump rather then the droppingvthe tank , must re-connect, the ground wire to the frame where you unpluged the tail light wires for the bed removal, or you end up looking at this video - simply for a quick test after install of new pump , with the bed still off .... before installing the bed . all mechanics check their work ....
cool man, I'm glad it helped. The context of the video was, this was recorded during my Engine Performance class at Rosedale Technical College. So when I do these, I am teaching many different aspects of troubleshooting all at the same time. So I understand what you mean.
@@ScannerDanner iGjgor
Scanner Danner is awesome!
+Michael Hart thanks Michael, I'm really not, I just enjoy what I do.
I have a 99 Ford contour I'm trying to see if fuel pump bad the car stalls every now and again won't start right away the first like 3 tries but eventually it does it starts right up .now when heats on I'm smelling burnt rubber coming through the vent .lately the car has stalled it has like pushed a little like pulling me .is this My fuel pump and how much do u think it will cost to replace opinions please???!!!
@@ScannerDanner help got the same problem 4 mecanic and no luck do you have a shop in Texas
Thanks @ScannerDanner great explanation, I know I have a bad pump (not crossed wires) I need to figure out how to change the pump.
Excellent video, I don't know crap about car. but I understood everything.
For sure, but I was getting third hand info. on this one. I never talked to the owner, just the owners friend who dropped it off at the school. Not sure what that guys was thinking:)
Minute 23 ... that is so funny! A long time ago, one of my brothers (brother 1) installed a new radio in his truck. Having not followed the installation AT ALL!), he connected all of the speaker wires (positive and negative) together. When there was no sound, he called my other brother (brother 2) to help. Brother 2 discovered the discrepancy, and now the infamy of his mistake lives in family legend for evermore. Anytime I'm discussing electrical stuff with brother 1, he's always eager to have brother 2 come help. (Names withheld to protect the guilty.)
this may be your problem. remember the relay can work (click) but still not provide power to the pump if there is a problem with the load side switch contact or relay pin contact problem. The burned pin in the PD box suggests poor contact with the relay pins. This would be unwanted resistance in an unwanted location which equals HEAT. This will cause loss of power to the pump.
Thanks for sharing valuable information on regulator pressure
thanks for watching!
can you define very weak? test light or voltmeter?
If you jump the load side contacts of the relay will the truck run? (jump 30 and 87 and DON'T jump 85 and 86)
thanks for the follow up! nice find
@5am8011 85 was a switched feed for the coil, 86 was coil ground (constant). I agree about pin 87 and 30 being mixed up, but it was clearly marked 87 on the relay and it was hot all the time (load side feed). Maybe the relay was marked wrong because the diagram shows pin 30 being hot all the time and pin 87 being the N.O. contact and 87a being the N.C. contact. Either way I have seen 4 pin relays wired like that, but the 5 pin shouldn't be, so I think the relay was marked wrong.
Yes, the next thing would be to check for spark and injector pulse and tell me what you are missing.
The PCM needs an RPM input to power this circuit cranking but that doesn't answer our no power during the key on cycle. You know this power will only be there for 1-2 seconds right? So if no power for sure then we need to go toward the PCM powers and grounds next.
With the key on see if you have a 5v ref. on one of the TPS wires. This can answer a lot of questions for me.
Most likely it is from a weak pump. Watch my other videos on GM CPI systems. I describe in more detail why this happens on your system with the mechanical poppet nozzels.