Hello Friend has 95 s-10 4.3 vortec. It runs rough and when she drives it the first day it was sluggish. Every day it loses top end down to about 40 mph now. no check engine codes. Mech did tune up wires plugs fuel filters dist cap. Same problem. i am not familiar with this spider injection. I did notice very Raw gas smell in engine compartment. I see no leaks. I saw a posting on another site where fuel lines in plenum are bad to crack. Says you can remove manifold tuning valve on top of plenum see if gas is laying on lower manifold. Is this the round sensor on top of plenum under vortec cover.The exhaust does not smell extremely rich. I have an automotive degree but have been out of thefield for awhile. So any help would be appreciated.

 

If you have a fuel pressure test gauge, you could determine if it is a leak inside the plenum before popping anything open, but you can either remove the MTV valve or the whole upper plenum. If you decide to take the upper plenum off, you should have a new gasket before doing so. With the upper plenum off, you can pressurize the fuel system and inspect for leaks.

 

i have a 2000 blazer, and mine did just about the same thing.. i wheel it hard, and coming out of the woods i noticed i had no pick up. turns out i completely engulf my oxygen sensors in mud and clogged my catalytic converter. the gas smell was because of the clog, at least thats what i was told. $625 later, my babys back on the trail take it to a mechanic, a TRUSTWORTHY one.. ask them to check it out