runs bad need help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ricsess · 01-08-2019, 03:00 PM

i bought a 1989 chev 3500 not running i replaced coil ign module ign pickup in disc cap rotor runs real bad put timing light on it timing seems to be on only thing i can think of is timing chain its a 454 engine
thanks for any help

sweetk30 · 01-08-2019, 05:30 PM

carb or tbi injection ?

ricsess · 01-09-2019, 12:14 PM

it has tbi seems to be working good has new injectors

68gmsee · 01-09-2019, 10:31 PM

Running bad doesn't say much. In order to help we need more info like how is it running bad -missing out, backfiring, no power, etc. Also, is it all the time or when it's cold.

You've done some of the isolation by replacing some ignition components but I have seen problems with older spark plug wires going bad. Couple of months ago brother in law's truck was running bad missing and lacked power. We unplugged spark plug wires to isolate and found one did not change the missing out. We took spark plug out and grounded it to the engine and had no spark. Turned out to be bad plug wire.

**kwmech** · 01-10-2019, 01:55 AM

On the 454, under the tbi itself is a cast iron water plate. Real common for the intake gasket (under the plate) to blow out in the EGR corner of the plate creating a vacuum leak

01-08-2019, 03:00 PM	#1
ricsess Registered User Join Date: Feb 2013 Location: West Paris Maine Posts: 3	runs bad need help i bought a 1989 chev 3500 not running i replaced coil ign module ign pickup in disc cap rotor runs real bad put timing light on it timing seems to be on only thing i can think of is timing chain its a 454 engine thanks for any help

01-08-2019, 05:30 PM	#2
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: runs bad need help carb or tbi injection ? __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great.

01-09-2019, 12:14 PM	#3
ricsess Registered User Join Date: Feb 2013 Location: West Paris Maine Posts: 3	Re: runs bad need help it has tbi seems to be working good has new injectors

01-09-2019, 10:31 PM	#4
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: runs bad need help Running bad doesn't say much. In order to help we need more info like how is it running bad -missing out, backfiring, no power, etc. Also, is it all the time or when it's cold. You've done some of the isolation by replacing some ignition components but I have seen problems with older spark plug wires going bad. Couple of months ago brother in law's truck was running bad missing and lacked power. We unplugged spark plug wires to isolate and found one did not change the missing out. We took spark plug out and grounded it to the engine and had no spark. Turned out to be bad plug wire. __________________ 68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive...

01-10-2019, 01:55 AM	#5
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,388	Re: runs bad need help On the 454, under the tbi itself is a cast iron water plate. Real common for the intake gasket (under the plate) to blow out in the EGR corner of the plate creating a vacuum leak



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