73-87chevytrucks.com

General Site Info => General Discussion => Topic started by: Dr_Snooz on January 23, 2012, 11:32:11 pm

Title: Question about 1990 C3500
Post by: Dr_Snooz on January 23, 2012, 11:32:11 pm: Since my '86 crew cab bent all its valves, I'm driving my '90 C3500. The drive train is essentially the same as the square bodies: 454, TBI, 3L80 (TH400), 14-bolt axle. The '90, however, is not a square body. I've looked around for a dedicated site with really knowledgeable members, like here, but I can't seem to find one, so I'm asking this here. Hope that's okay.

The truck runs great. It starts easy and runs smooth. The only problem is that at very light throttle, the truck sputters and coughs and really won't smooth out until I step harder on the gas. I don't have a CEL. Does anyone know what's up?
Title: Re: Question about 1990 C3500
Post by: yellowk20 on January 23, 2012, 11:43:18 pm: I've found that that for any TBI or TPI gm info the best place to start is thirdgen.org TONS of info and decent folk over there
Title: Re: Question about 1990 C3500
Post by: Captkaos on January 24, 2012, 01:59:48 pm: This site covers all the roundedline (squarebody) trucks from 1973-1991, but... The engine drivetrain in the C\K trucks of 88-91 are identical to the 88-91 R\V trucks.

fullsizechevy.com is dedicated to those years, but we can help also.

We need some background on the problem. Did it just start this or has it always done this.
How is you cap/rotor? have you verified the SES light is working?
Title: Re: Question about 1990 C3500
Post by: Dr_Snooz on February 28, 2012, 10:34:24 pm: I thought I'd close the loop on this instead of leaving it dangling. I didn't do anything, but the problem has gone away. The truck spent a lot of time sitting in the last few years, so I suspect it was some kind of gum or varnish build up that has since gone away.

Thanks everyone.
Title: Re: Question about 1990 C3500
Post by: Dr_Snooz on December 23, 2013, 10:03:06 am: Update: the problem kept recurring and finally got really bad. Though I had checked out the cap and rotor and tested the resistance of the plug wires when I first got the truck, I never looked at the plugs. Turns out they were Champions. I replaced them with Delcos (along with a full tune up) and the truck runs amazingly well now. I'm embarrassed that I drove it for so long with those junky plugs. :(
Title: Re: Question about 1990 C3500
Post by: werewolfx13 on December 23, 2013, 11:15:17 pm: I'm curious...why hate on champion plugs? I have better luck with champs than Autolite, delco, or bosch plugs in my trucks....and I run NGK in my car and bike, champions in all my small engines...
Title: Re: Question about 1990 C3500
Post by: Captkaos on December 24, 2013, 10:59:55 am: I am running Champions in my turbo truck, but I am not a plug snob like I am with car makes. I have ran all of the mainstream brands with good results.
Title: Re: Question about 1990 C3500
Post by: Irish_Alley on December 24, 2013, 11:57:03 pm: in my 94 i have the same problem, changed cap rotor and wires will have to see about the plugs.