1990 gmc 1500 4.3 running a little rough - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Squareforceone · 01-26-2015, 12:59 AM

My 1990 gmc with the 4.3 has been running rough since i bought it and i'm not sure what to do. It has new cap, rotor, spark plugs, air filter, fuel filter, and has had some fuel system cleaner run through the tank yet it still has a bit of rough idle to it and just doesn't run quite like it should. I have no check engine lights or anything of that nature.. Not sure what else to try except maybe plug wires?

Squareforceone · 01-26-2015, 02:41 PM

anyone?

ChevyTech · 01-27-2015, 09:48 AM

New plug wires may help.

Did you put the cap, rotor and plugs in it, or do they just look new?

Testing the engine compression would be a good idea.

I would test the fuel pressure and check for vacuum leaks.

Squareforceone · 01-27-2015, 02:53 PM

yep cap and rotor at the same time 6 months ago, plugs were new and gapped correctly last week. I don't think theres any vaccum leaks where would i check fuel pressure at on this engine.

ChevyTech · 01-27-2015, 03:30 PM

There is no fuel pressure test port. The instructions in this thread are correct for your truck.

http://67-72chevytrucks.com/vboard/s...d.php?t=375132

01-26-2015, 12:59 AM	#1
Squareforceone Registered User Join Date: Nov 2010 Location: Rustville USA or southeast Ia Posts: 654	1990 gmc 1500 4.3 running a little rough My 1990 gmc with the 4.3 has been running rough since i bought it and i'm not sure what to do. It has new cap, rotor, spark plugs, air filter, fuel filter, and has had some fuel system cleaner run through the tank yet it still has a bit of rough idle to it and just doesn't run quite like it should. I have no check engine lights or anything of that nature.. Not sure what else to try except maybe plug wires? __________________ Rust is better than rice.

01-26-2015, 02:41 PM	#2
Squareforceone Registered User Join Date: Nov 2010 Location: Rustville USA or southeast Ia Posts: 654	Re: 1990 gmc 1500 4.3 running a little rough anyone? __________________ Rust is better than rice.

01-27-2015, 09:48 AM	#3
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: 1990 gmc 1500 4.3 running a little rough New plug wires may help. Did you put the cap, rotor and plugs in it, or do they just look new? Testing the engine compression would be a good idea. I would test the fuel pressure and check for vacuum leaks. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-27-2015, 02:53 PM	#4
Squareforceone Registered User Join Date: Nov 2010 Location: Rustville USA or southeast Ia Posts: 654	Re: 1990 gmc 1500 4.3 running a little rough yep cap and rotor at the same time 6 months ago, plugs were new and gapped correctly last week. I don't think theres any vaccum leaks where would i check fuel pressure at on this engine. __________________ Rust is better than rice.

01-27-2015, 03:30 PM	#5
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: 1990 gmc 1500 4.3 running a little rough There is no fuel pressure test port. The instructions in this thread are correct for your truck. http://67-72chevytrucks.com/vboard/s...d.php?t=375132 __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.



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