1990 Chevy truck running prob.????

[weum]

I have a 1990 Chevy 2500 with 5.7 EFI that had been sitting for two years..I fired it up the other day and it will idle fine but once you start to let off the clutch it starts missing and will die..you can rev. the engine up and it will miss and carry on.. I do no the altenator is bad...putting out 5 volts. but i have put a brand new charged battery on it and it still does this..
here is what i"ve tried / replaced any suggestions??
New fuel filter, drained tank added new gas with heat water remover, new spark plugs, new distributor cap and rotor button.

 

[bradk]

A few things come to mind.

#1 Restricted fuel supply usually caused by a twisted steel line from replacing rusty/stuck fuel filter at line nuts.Look at lines closely.

#2 Resticted exhaust or plugged catalytic converter.Try taking out the O2 sensor at driver's side exhaust and running it with removed.

#3 Corroded secondary coil cable at ign coil.Pull it out and see what it looks like.

~brad

 

[dave guest]

Don't know about 90 but I had 88 chevy. When you disconnect battery, you lose 15 or 16 settings. You have to connect battery securely and drive for maybe 50 or 100 miles and let computer relearn all these functions. Every times batt is disconnected, lose everything and start all over. Fix alt first.

 

[joe e-tx]

was there lots of white fuzzy stuff in distributor??.computer needs 11.5 volts to run program. next there was a up grade to dist. shaft needs spiral groves under pick up coil to keep oil from filling dist.any white stuff in dist i would get new pick up coil or rebuilt dist. from part store.at that age i would install a new coil wire to dist,six cylinders had a recall for that and we had some trouble with v-8s. get alt. fixed or replaced(replaced not cheap). should run good,had customers with 500000 miles and rum like new.
joe

 

[tlak]

See if the plug wire are laying on the exhuast. More towards the back were they bunch up, probably burnt up. Chevy products have to have both the batt cables disconnected and the Cables (cables only, no juice)touched together to reset the computer. Just disconnecting the battery resets the clock.

 

[Anonymous-0]

I've found out with my '90 ford that you can't milk them along like the older ones. If something isn't right, you'll have to fix it right away. If it was me and I couldn't fix the alternator right away, I'd get it running and hook it up to a another running vehicle with jumper cables or battery charger (if the charger has a fused circuit for safety) and see if it runs better. Anything can happen in two years as far as corroded wires, grounds, mice, etc . If it was good when it was parked, shouldn't be too hard to fix now.

Good Luck,

Dave

 

[HeyPigFarmer]

Also pull off the air cleaner and look into the throttle body to see if you are getting a good spray pattern out of your injectors. If not those are easy to remove and clean.

 

[Anonymous-0]

FYI.. may or may not apply to your truck. I have a VW as a daily driver that ran fine but just wasn't acting just right. Leave the lights on 5 minutes without it running and it would start weak if at all. Radio never came in the way others would and some things like power locks and rear wiper were real sluggish. Got to the point that sometimes for no reason I'd have to roll it or jump it to start. Come to find out that the alternator was barely putting outenough amps to push a charge into the system. Replaced the alternator last night and it was like driving a new car this morning. Brought the old alternator and had it checked at the motorpool on post (I'm in a Military Community) and it is shorting itself out on a section of the contacts for the brushes (commutator???). Guess it was always a problem that drove things crazy while running, but was like roullette when stopped. If it didn't stop on the bad spot, no problem.
Hope that helps someone.

Dave