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02-20-2018, 11:48 AM | #1 |
Registered User
Join Date: Aug 2011
Location: Gainesville, Texas
Posts: 127
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No voltage from PCM fuel relay trigger
This came out of nowhere. I've had it hooked up for several months now and it's worked really good. Now I'm not getting any voltage from my PCM trigger to my fuel pump relay. If I wire around it, the fuel pump kicks on. I've been all over checking wires, fuses, grounds, etc.. and this is baffling me. In a desperate measure, I tried replacing the crank sensor and still nothing. I've read where guys have encountered this kind of issue theirs wound up being wired wrong or a grounding issue. I haven't changed anything up, so I'm at a loss.
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1972 GMC Jimmy 6.0/4L65 1972 Chevrolet long bed 1/2 ton |
02-21-2018, 03:34 PM | #2 |
Msgt USAF Ret
Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,715
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Re: No voltage from PCM fuel relay trigger
This is a little out of my league but I kinda understand it. I checked google and found this site with the same problem you are having so I am pasting the link for you.
http://www.pirate4x4.com/forum/gener...fuel-pump.html
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
02-21-2018, 06:24 PM | #3 |
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Join Date: Mar 2014
Location: Corvallis, OR
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Re: No voltage from PCM fuel relay trigger
I think is issue is one of two places. Either an ECM issue, or a wiring issue.
It sounds like you have the wiring figured out. Should have 12 v fused power to relay, good ground, wire to fuel pump, and the ECM signal. On the ECM side, there could be something that is preventing it from powering up the fuel pump. Like a fault code. Might want to try checking codes, then resetting the computer by disconnecting the battery.
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1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205 1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears 1996 Chevy Suburban K1500 350/4L60E |
02-22-2018, 01:35 PM | #4 |
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Join Date: Aug 2011
Location: Gainesville, Texas
Posts: 127
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Re: No voltage from PCM fuel relay trigger
Well I got it going. Cannot tell you what was wrong as I didn't replace anything. The wires I cut while trying to diagnose the issue, I re-soldered and heat shrinked and all of a sudden it's working again. Makes no sense. I've taken my time and carefully inspected every wire, no cuts or slices in any of them to ground out anywhere...I was fixing to get another PCM or just put the fuel pump on a switch, but now it's fixed. Thanks for the help anyway fellas.
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1972 GMC Jimmy 6.0/4L65 1972 Chevrolet long bed 1/2 ton |
02-22-2018, 05:51 PM | #5 |
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Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,223
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Re: No voltage from PCM fuel relay trigger
If there is a problem with the ignition the ECM won't kick in the fuel pump.
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02-22-2018, 06:57 PM | #6 |
Registered User
Join Date: Aug 2011
Location: Gainesville, Texas
Posts: 127
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Re: No voltage from PCM fuel relay trigger
Yeah, I read somewhere that if the crank sensor goes bad that the PCM won't kick the fuel pump on. I replaced it and nothing changed. I could hear the throttle body do it's deal when the key was on, so I'm assuming my PCM was still getting power.
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1972 GMC Jimmy 6.0/4L65 1972 Chevrolet long bed 1/2 ton |
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