Crank no start gauges always on while battery is hooked up?

LOST MN HUNTER

MEMBER
1995 GMC YUKON
5.7L
V8
4WD
AUTOMATIC
145,000 MILES

I replaced a blown up 95 5.7 with a 91 5.7 Truck fired right up. But it wouldn't shut off with the key. All lights and gauges are on with battery hooked up. Pulled coil wire to shut it off. It won't start now. I have Spark and did jumper wire on fuel pump relay. Pump runs but no fuel out of TBI. I have been told I have ground issues. Cleaned and removed all ground wires. Added more grounds to engine/frame and body. I'm really stumped at this point. Engine turns over good. All gauges are on with key out of ignition. Replaced PCM with a used one. Didn't change anything. Need help guys!

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Will the engine run with starting fluid? Also how does the engine sound while cranking can you please upload a short video with your phone? You can upload it here in your response. I am wondering if you lost compression. We should run the codes as well. Let's go over this guide:

https://www.2carpros.com/articles/car-not-running-advanced

and

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

It does sound like the PCM is still bad, running the codes should help us. Please go over these guides and get back to us.

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Thursday, September 21st, 2023 AT 9:47 AM

LOST MN HUNTER

MEMBER
2 POSTS

Replaced PCM again. No change. Good battery.
Good compression, fuel pump runs but nothing comes out of the throttle body.
Engine will run on either.
Lights still on the dash without key in the ignition. Jumped pin 87 and 30 to rin fp.
I don't own a code reader so I have no codes to give you.
This is my engine bay. Nothing like other picture I have seen with fp relay on firewall.
Ready to give up on this pos.

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Thursday, September 21st, 2023 AT 11:32 AM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

We can fix this; can you remove the fuel injector connector and then turn the key on and use a test light to see if you have 12 volts on one of the wires? Please check out this guide:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please go over this guide and get back to us.

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Saturday, September 23rd, 2023 AT 10:30 AM