'90 GMC Starting Trouble

caneye · September 13, 2004

'90 GMC 1500 5.7 L

Within the last couple of days the truck has began running rough. Now the truck will only intermittently start. If it does fire it will stall right away. Had a friend turn the engine over as I watched the injectors in the throttle body. No fuel comming through.

1.) Loosened the fitting for the fuel line to the throttle body. Fuel Present.

2.) Fuel Pump and filter are new.

3.) Replaced the PCV Valve.

4.) EGR Valve seems to be O.k. (ie diaphram moves with slight pressure)

Any ideas as to why she will only intermittently fire and then stall.

Thanks,

Jeremy

Mike G · September 13, 2004

I would start by pulling the ignition module out of the distributor and having it check or tested at your local parts store. Those darn things electonically control a lot of other engine parts and if they are on the fritz, she won't go...

--Mike G

sdtahoe · September 14, 2004

I agree on the ignition module, my '90 GMC had the same symptoms (after it died at 70 mph). I guess with out a signal from the ignition module the injectors don't pulse.

caneye · September 14, 2004

Thanks guys I'll give that a try.

Jeremy

speedde423 · September 14, 2004

It couldn't hurt to check the fuel pump fuse. It's on the passenger side firewall under the black plastic piece.

If you have access to a code reader, you might want to try that. If not, you can use a piece of wire to get the code to display on the check engine light, but I don't know which two to jumper together offhand.

My truck had problems somewhat like that, it would fire up, run a few seconds and then quit. I think the Throttle Position Sensor was part of the problem, but I ended up changing the computer, distributor(corroded like crazy, pieces fell out when shaken), and some other parts. I hope you don't have to do that.

-Brian

smit · September 14, 2004

My 90 5.7 Chevy stepside Z71 was acting similar. It would start sometime, sometime not, run rough, stop dead in traffic. Took it to the dealer. {under warranty at the time} turned out to be a bad distributor. It was jumping time and raising holy hell. They replaced it. Ran great for another 40k.