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?

Re: 1990 gmc 1500 4.3 running a little rough
 

anyone?

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.

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.

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