How to test an electric fuel pump - using a test light
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- Опубликовано: 2 фев 2012
- 2001 GMC 3500 8.1L engine with no fuel pressure. In this video I am showing how to test the fuel pump electrical circuit using a test light and scan tool.
Engine Performance Diagnostics chapter 16
Symptoms
- no start
- no fuel pressure
Fix
- replace faulty fuel pump
Tests shown
- how to measure fuel pressure
- how to test the fuel pump relay
- how to test for proper power and ground to a fuel pump
- how to test the transfer pump
- how to test for a proper ground on your test light
- how to command a fuel pump relay to turn on with a scan tool
- how to test the computers control of the fuel pump relay
- how to determine fuel pump wiring without a diagram
Tools used
- scan tool - Autel MS905 MaxiSys Mini Diagnostic System
www.jbtoolsales.com/autel-ms9...
- incandescent test light www.jbtoolsales.com/otc-3633-...
- back-probing tools - AES' Electronics Accupuncture Probes www.aeswave.com/cart.php?m=aff...
- S.U.R. & R FPT22 Deluxe Fuel Injection Pressure Tester Kit
www.jbtoolsales.com/s-u-r-r-f...
Playlist
- (Chapters 14, 15,16) Fuel Delivery and Fuel Pressure Testing
• (Chapters 14, 15,16) F...
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• Fuel psi less than 50 ...
- Low Fuel Pressure from a bad fuel pump ground (Ford Ranger)
• Low Fuel Pressure from...
- How to test an electric fuel pump (no fuel psi testing) Ford
• How to test an electri...
- Fuel pump electrical circuit diagnosis (no fuel pressure testing) GM • Fuel pump electrical c...
- No Start No Fuel Pressure Troubleshooting
• No Start No Fuel Press...
- How to test fuel pressure, injector pulse and spark with basic tools • How to test fuel press...
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.
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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]](/img/1.gif)
Oh ya, let me just break out my biodirectional scanner. Most people who watvh you tube for auto repair advice have a $20,000 scanner in their garage. ,,,,🙄
Thanks. Thought you where gonna temporarily swap relays. Can't believe last person that wrote was 7 years ago, don't know how many of us screwed out here appreciate you sharing your knowledge, you'll be helping people 50 years from now.
There is problem with the sound....??
Big difference between Test Lights and Circuit Testers... Test Lights are usually the low impedance Incandesant Bulbs that can flow sufficient amperage to complete a circuit and overload electronics. Modern day Circuit Testers are High Impedance and as such do not load the circuit and do not pose a risk to electronics. I use both. A Test Light for down and dirty testing on things like auxilliary lighting, and a proper circuit tester for anything involving fuses, relay bases and electronics.
@ScannerDanner Wait, it think I get it. The reason there is only 300mv running through the ground wire with the pump running is because the pump is drawing 12v, which leaves about 300mV on the power side and 300mV on the ground side out of a total of 12.6v. And a frozen pump will still draw 12 volts, rights?
sound drops out at the fuse box
very much appreciate the comment about ADAPTERS which allow the relay to remain plugged in , for testing purposes !!!! PRICELESS TO KNOW !!!!!
correct, and with that comment, you yourself have just condemned the pump! Because a good pump would load the circuit and cause voltage drops in the wires that we would have seen as soon as we plugged in the connector.
Humn same on a Saturn I assume
Do NOT use cheap (harbor freight type) pressure gauges... Bought one, showed 48 psi (koec) on a chev express van. Compared to a co workers new Matco gauge, which showed 60 psi (koec) Cheap pressure gauges can create faulty diag. Glad I re checked, as I was gonna replace the injector network under the intake system. Spend the extra $ for a quality gauge, or at least compare with a second gauge.
Thanks I replaced the fuel pump relay, but because of how you showed the testing at the fuse block, I discovered I simply put the relay in backwards, with the numbers corresponding to the ground and GM using the positive, Works now! Thanks
Amazing. On every video I am getting my knowledge better and better and even though I am a DIY guy I have started talking to myself and proposing steps before being told on the videos
exactly confirming the problem is NOT a bad ground. you can call it faulty logic if you want to, it's not. Unless you want to tell me that the pump motor circuit is open and you have a bad ground at the same time...not going to happen. test light doesn't light on the ground = it is NOT a bad ground that is causing the pump to not run! I agree the ground circuit isn't loaded but so what in this case. you have correctly identified a bad pump!
Man this is a quality video and very universal. Great fundamentals, i will keep this as a reference of my own. Many people young and old will enjoy your lesson
As a young parts guy I love your videos. From watching I've grown to love the electrical and computer side of automotive repair which a LOT of people shy away from and treat it like witchcraft. I'm saving my pennies for your Ebook so that I can better help my customers with their issues (With the disclaimer that I am in no way a pro technician and could be wrong)
Anyways keep them coming! great stuff Mr. Danner :)
God is blessing you with a great gift and you are sharing and that is what i call true success. thanks for your hard work may he bless you greatly.
first, substituting a know good component is not troubleshooting, not to mention when you work on 20 different car lines like I do you don't have vehicle specific relays laying around. Also there is NOT one way to do things. I'm sure your method works great for you. You come in here and want to critique my methods and tell me I am wrong? You have yet to do that. Show me where I am wrong. Give me a scenario where the methods I show in this video will lead to an inaccurate diagnosis.
Nice video. Having trouble with my 2002 2500 Silverado. Now i know how to test before moving on to pump removal. Hoping just a bad ground. Very informative. Thank you.
This was my 1st video...I did not have to look for another source of info.
go to my website scannerdanner d o t c o m
fill out your name and email and I will send you more information about the ebook.
Thanks!