'90 Silverado running rough (Full Version)

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'90 Silverado running rough

  

jd512k -> '90 Silverado running rough (4/30/2008 9:22:15 PM)

  Hi all. Brand new memeber here. Moved this post from Gen Tech to here...

Just bought a '90 Silverado, 350 auto. Have replaced all fluids, filters, PCV, & plugs. Had a new flowmaster installed yesterday, and have run fuel system cleaner through.. It's running pretty rough from off idle to ~2000/2500 rpm (No tack, so I'm guessing on the rpms)... then purrs like a kitten, from there on up..

There's no popping from the exhaust to speak of.. just a noticeable, rough running vibration from the motor.. strong enough I can feel it through the floor, steering wheel & seat.. and see it in the mirrors..

Any suggestions on where to start tinkering would be greatly appreciated!

Thanks!
JD

  
cdusthockey -> RE: '90 Silverado running rough (5/1/2008 12:07:36 AM)

not sure, but id say check your cap and rotor?  again not sure if its got one, because im not so knowledgeable on those older trucks.  did it run like this when you bought it or did it just start?

northey87 -> RE: '90 Silverado running rough (5/1/2008 5:13:03 AM)

It may be in need of a tune-up. And yes it does have a distributer with a cap and rotor, kind of a pain to get to being on the back of the motor. When you say "no tach" are you saying it doesn't have one or it doesn't work?

jd512k -> RE: '90 Silverado running rough (5/7/2008 4:52:15 PM)

Thanks for the replies.. Yes, it ran like this when I bought it. I've replaced the plugs and PCV valve, air filter, etc..  The truck does not have a tach.. (wish it did.. my '91 350/5spd had one).

I've been busy replacing shocks and doing the brakes.. after those are done I'll replace the cap 'n rotor.. see if that fixes the rough running..

Thanks again.. I'll let ya' all know if it still runs rough afterwords.. Thinking I may pull the TBI off and give it a good cleaning too.

JD

northey87 -> RE: '90 Silverado running rough (5/7/2008 7:32:06 PM)

Try running some BG 44X through the gas, really really good stuff, I'll poat a link tommorow where you can buy it online. 
Try and get some pics up, we all love pics on this forum.

bossman78 -> RE: '90 Silverado running rough (5/7/2008 7:49:33 PM)

This might sound stupid but i've always learned start w/ the simple things. but did someone mess with the idle control? sometimes if a car was running rough people will up the idle rpm's so the car won't stall out.

jmack91z28 -> RE: '90 Silverado running rough (5/8/2008 4:47:45 AM)

Thats a good point bossman.  It's a TBI, so don't you have to have the computer tuned to adjust the idle?  It's not as simple as just turning a screw is it, cause I have a TBI and have never cared to check.  But I would assume...

  

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