Rough starting, running rich


kpajak
09-22-2004, 01:53 AM
A friend of mine recently helped me do a tune up on my '93 Jimmy 4.3 L Vortec. We replaced the plugs, wires, distributor cap, rotor, PCV valve and fuel filter. Did the fuel filter first and started the engine to make sure that was right before doing the other stuff.

After replacing the other parts, we initially couldn't get the engine started. The engine had been rebuilt. Through process of elimination, found that when the engine was rebuilt, the distributor wasn't lined up exactly as "the book" called for. Moved all of the spark plug wires counter-clockwise by one and it started. It ran great the rest of that day. Next day, and every day for the rest of the week, when starting in the morning or after it sits for over 1 hour, it's very difficult to start. Can smell gas when it's started and runs rough at idle.

I've checked all of the vacuum lines and connections, especially around the area where we were working. I put a bottle of injector cleaner and a full tank of gas in the day after the work was done. I'm wondering if it's possible that the fuel injector may be stuck too far open. I also suspect the EGR valve because that had caused a rough idle condition once before.

Any other suggestions would be greatly appreciated?

jmk_1618
09-22-2004, 11:55 AM
If you have the Vortec "W" motor than this is probably your problem.

It sounds like one or two of the components of your CPI unit are leaking gas. This is a very common problem with the vortec "W" motors. Additionally, I had to replace these parts on my '92. The components that go bad are the fuel line (nut kit) that go to the injector and the fuel pressure regulator. They leak gas which gets into your intake and causes the problems.

Its not a very hard problem to fix, or expensive. I got the lines at a local GM dealer for $50 and i ordered the regulator off of 1aauto.com for $60. All of this is located under the plenum which is underneath the orange Vortec cover.

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