Need some Mechanical help
 

First off thank you all for your help....scenario below...
Truck, 1985 Silverado 454 74k original miles

Driving home from work, when i let off the throttle to coast up the ramp, heard a back fire, then another and then engine died, I pulled over and pedaled the gas a few times and it ran rough, while manipulating the pedal to get her home, pulled up to house and it died again.

Yesterday went out and fired up like normal and drove around for about 20-30 min, then it started doing it again, as long as i keep my foot on the pedal some it stays started but if i take my foot off it runs rough and will die.

Any thoughts? Fuel pump was initial thought....help is needed as i want to have the beast representing daily on the road as the best truck made.:bann:

Re: Need some Mechanical help
 

Oil pressure is great, battery is great, all things work flawless till now.

Re: Need some Mechanical help
 

I was gonna say TBI coolant temp sensor but see its an 85' so that doesnt apply

Re: Need some Mechanical help
 

one thing i noticed since buying is the temp gauge has always looked to read low, it doesn't sit up by the 200* mark

Re: Need some Mechanical help
 

My first two items. Fuel pump and ignition module. Ignition modules act funny when they get hot. Have it tested for free at a parts store.

Re: Need some Mechanical help
 

pardon my ignorance, is the ignition module something i can take into them for checking, as the truck itself is capable to take in? also, do these trucks with dual tanks have in tank fuel pumps? or one man pump and a tank divert valve?

Re: Need some Mechanical help
 

assuming the module is under the Dist Cap?

Re: Need some Mechanical help
 

Yes, the ignition module is under the cap. You have remove it.

Looks something like this: http://www.gasgoo.com/auto-products/...407/15832.html
Coat it with die electric grease before installing it back.

Only TBI and fuel injected trucks have in tank pumps.

The fuel pump is on the passenger forward side of the engine.

Another common problem is the Electronic Spark Control (ESC) module. Read about it here on how to troubleshoot it and bypass it.
http://www.73-87.com/7387garage/drivetrain/escrepl.htm

Re: Need some Mechanical help
 

What about the fuel filter or the fuel sock in the tank?

Re: Need some Mechanical help
 

The fuel filter is up on the carb. Just follow the fuel line. Carefully remove the line from the carb. The filter is about 1" long. The filter goes in only one way. It has one end with a rubber end.

Re: Need some Mechanical help
 

I'm gonna take a shot in another direction. when you first start it cold it runs fine for about 20 minutes if I read your post correct, so after the motor comes up to temp is when the problem starts. This is just a suggestion crank it and let it just idle until the temp starts to come up take a can of starting fluid and shoot it around where the intake mates to the heads if and when the engine shuts off you have found your problem. Intake leaks always cause backfiring and usually are more profound once the heat in the motor gets up. Your heading sez 85 454 w/74k original you may just need to snug some intake bolts!

Re: Need some Mechanical help
 

Fuel pumps on the mid 80s big blocks have been known to fail on a regular basis. Good chance that is your problem. I have a late 85 454 and have had 2 pumps on it in under 100K.

Re: Need some Mechanical help
 

Thanks for such quick help you all. As always the forum family strikes again for some help. Shes back on the road and no failures since replacing the ICM, took about 30 min and I was out cruising to see if it was fixed, so far so good. Thank you all so much.