Hope this will help someone,
I ran this post a few days ago but I did not get any help, I have solved the problem and hope this will help someone, Here is the question that was asked
and the solution at the end.
“Can you help?
This is a 1994 GMC jimmy with a 4.3 vortec engine.
The problem is
1-- hard starting, -- turns over to many times before starting but it
Does always start. This is when it sets awhile, Starts ok if restarted
Within a few min.
2---Rough idling but is better at higher speed.
3--At times when idling or at low speed it will sputter. This is most noticeable
After engine is hot.
4---black soot at exhaust pipe, This engine does not burn oil
Changed cap, rotor, plug wires and plugs, Notice that three of the plugs,
The ones from Driver side has what looks like black soot, not oil
At high speed this engine runs good with normal power and it does not
Also, it has a new fuel pump and fuel filter.”
This is what I found causing the problem.
Removed plenum, Found puddles of gas under plenum (where injectors are, )
Found one of the plastic lines split. I replaced both lines from injectors to connectors Where lines pass through back of engine.
I also replaced the fuel injectors, (The injectors possibly were good but I did not want to take a chance with them.)
Now jimmy is running like new. The job was not hard after I got over the fear of working on this type system.
I hope this will help someone.