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1989 Chevrolet 1500 5.7 Running Rough, dies

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Jun 30, 2011, 5:58 PM

Post #1 of 3 (10425 views)
1989 Chevrolet 1500 5.7 Running Rough, dies Sign In

1989 Chevrolet 1500 Silverado
Engine: 5.7
Mileage: 148k miles showing

Where do I start on fixing this. I haven't replaced anything yet, figured I'd get advice first rather than simply throwing possible parts at it to fix it.

Truck runs great driving normally. When I start it, sometimes it dies, and I have to give the gas pedal a pump to keep it running and it smokes alot at startup (seen smoke when pulling away from a light too). Then when I put it in gear, I have to give it gas to keep it running. At idle or at a light/stop sign, I can feel it running a little rough. I looked under the hood, and the EGR was bypassed, the firewall plugs for the heater hoses were bypassed, the a/c unit was removed (just bought truck yesterday). I didnt hear any obvious air leaking from vaccuum lines. It does have a small chrome breather I know I need to replace. I had parked it today at the revenue office and was in there about 30 minutes. I came outside and popped the hood when it wouldn't start, under the hood seems to be very hot (more than normal) but my temp gauge says I run between 160-210. 210 being the max it got to but dropped quickly and stayed down since. I covered the radiator with a rag and opened it, water wanted to spew out. Once I had it open, I dunno if it was because I slowly opened or if was really something else, but there were bubbles in the coolant. Best way to describe them would be like suds from soap lol. I put the radiator cap back on and it started after a couple cranks. It starts when cold, but after it is warm, it has a hard time starting. Being a new vehicle to me, I'll obviously be switching out spark plugs, wires, fuel filter, breather, oil, transmission fluid, trans filter, and flushing the radiator. Dropped by a friends shop and he said it could be the fuel relay. Then he seen the smoke when I started it and he said it might be something worse. The truck wasnt driven much lately before I bought it. It does have good power and take off. Runs smooth while driving. Thanks in advance for any assistance. If I need to give more info, lemme know and I'll get it to you asap. I looked through other threads and will certainly give a response as to the problems once resolved for others future problems.

(This post was edited by JesterzLaf on Jun 30, 2011, 6:00 PM)

New User

Jul 10, 2011, 11:58 AM

Post #2 of 3 (10377 views)
Re: 1989 Chevrolet 1500 5.7 Running Rough, dies Sign In

Update: did all those I mentioned before, plugs/wires/fuel pump relay/etc and still having problems. I followed the vacuum diagram and reconnected all the vacuum lines to where they need to go. The EGR diaphram is good. One new thing I noticed, the muffler looks like the pipe was shoved in in the front. When running, smoke comes out of both the muffler front and the end of the tailpipe. Maybe the exhaust is choking it? Friend is going to work that problem at the shop. When I started it up today, the truck idled kind of like with a lope, then leveled out and idled perfect. After a few minutes, it started loping again and eventually stalled after a few minutes of it loping. There is also a vacuum tree with one inelt behind the throttle body that was blocked off at the end of the hose. I looked at another truck, and instead of having the vacuum tree, it had a plug in that place.

Sorry, trying to be detailed as possible so I could get some help. I would just take it to a shop but I'm disabled veteran still fighting the VA for my benefits and barely staying afloat. Any help would be greatly appreciated.

Hammer Time
Ultimate Carjunky / Moderator
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Jul 10, 2011, 12:18 PM

Post #3 of 3 (10374 views)
Re: 1989 Chevrolet 1500 5.7 Running Rough, dies Sign In

First make sure you have no vacuum leaks, the EGR isn't sticking open from carbon and the EGR base plate isn't rotted out. Once all that is eliminated and you still have a problem, you may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.


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