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98 Silverado starts then immediately stalls

barnmech's Avatar
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Join Date: Feb 2011
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Cary, Illinois

February 8th, 2011, 12:40 PM   #1  
98 Silverado starts then immediately stalls

Hi guys, new to posting in the forums but I've been reading them for a long time. I work at a landscape shop and we're having a problem with our 98 silverado 2500 5.7L. We've been using it to plow snow and it worked just fine the other day. We parked it overnight as usual and when we tried to move it in the morning, it wouldn't shift from park. Left it running for a 1/2 hour or so and tried it again and it worked, and I pulled it into the shop to check fluids, powerwash, etc. Went to move it again and it wouldn't shift from park. Took the column apart and got the shift interlock lubed (it was sticking) and put it back together. Now the truck will shift from park with the key and brake on, but when I try to start it, it will start but immediately stall out. I've checked fuel pump voltage, relay, fuse, and pressure at the rail, I've also checked the oil pressure switch, all the necessary fuses, and replaced all spark plugs and wires. I'm at a loss. The truck has taken more cranks to get to start for about six months, but it always started and ran fine until now. I'm thinking it's the ignition coil or ign control module but I don't know for sure, and I don't have anything to pull codes from the diagnostic connector. Any ideas on where to go from here or should I just have it towed to a mechanic?

RacerX's Avatar
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Join Date: Aug 2010
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New York City USA

February 8th, 2011, 5:56 PM   #2  
if it starts then the Ig and fuel control components are fine.

Your problem is isolated to the Antitheft Program and or bad PCM/PROM chip. Now since you disassembled the column I think you may have arced some wires in there. Does it do this with the other keys you have for this truck? Open that column up and look for pinched wires.

The start inhibitor prevents the car from running if you try to start it with the wrong key. And the fuel run program is an output from the PCM to keep the pump energized. You can test this by using a VM on the wire that runs that and ground, which I dont know is in a 1998 but I do know it is the B part of the harness and should be blue. If it is at 12 KOEO when the relay is open and at 12 during cranking but drops to O during the run then the PCM is the center of the problem.

Do you have the resistor pellet in your key?

ToooTall1's Avatar
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Clovis, CA

February 8th, 2011, 6:11 PM   #3  
When dropping the steering column you may have disconnected or mess up the passlock system if installed, Has to do with the ignition switch lock cylinder. Something about a small magnet in the switch that tell the system that it has the correct key to turn switch, if not the passlock will start engine but then shut off fuel to it. Hope this helps.

barnmech's Avatar
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Posts: 2
Cary, Illinois

February 9th, 2011, 8:07 AM   #4  
I just noticed the dash lights were out, checked the fuse and sure enough, blown fuse for the guages. Replaced it, truck started right up. I could have sworn I checked ALL the fuses in the dash fuse block but apparently not. Thanks for the suggestions guys.

Last edited by barnmech; February 9th, 2011 at 9:54 AM.
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