1992 CHevy 1500 Rounning rough

fire-fighterNovember 18, 2009

I have a 1992 chevy 1500 4.3 engine. It was running great until last night. Started running rough and died out. Smelt like it was flooding it self and popped through TBI. Let it sit over night and stated fine this am. Let it run for about 5 minutes and purred like a kitten, then it started running real bad and could smell gas again. Now it wont start

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It could be flooding, or it could be bad ignition. The cam position sensor may be intermittent. This problem requires a good set of diagnostics to sort out. Start by readng the trouble codes.

It is possible that the TBI injector is passing too much fuel. This can be caused by a leaking valve in the injector, or messed up control current/voltage to the injector valve.

Abnormally low vaccum can mess with the engine controller.

We need someone to chime in here who has some experience with this particular engine and year.

    Bookmark   November 19, 2009 at 3:02AM
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Check the gas cap. It should have a one-way valve that admits air into the tank, but stop fumes from escaping. If this valve is missing (wrong cap) or plugged, a vaccum may develop in the tank especially in cooler weather.

A quick test: When the engine begins to falter, stop and loosen the cap. If this cures the problem, the cap is suspect. This won't work for engine controllers that have detection for loose caps.

    Bookmark   November 19, 2009 at 3:24AM
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I had unplugged the o2 sensor let it run for 5-7 minutes, balanced itself out, took it for a spin and it ran fine. Started it the next morning and wouldnt stay running but once I got going it ran fine. Went about 2 miles and ran rough again now its running real bad with the black smoke and gas fumes. Replaced everything to the left of TBI still running bad. Could the timing have jumped? Dies out when given gas...

    Bookmark   November 19, 2009 at 11:52AM
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Is this a TBI unit or a CPI unit? If it is a CPI unit they are mounted in the valley of the engine. They Can also have a problem leaking causing a rich condition. Below is an example of a CPI unit.


    Bookmark   November 20, 2009 at 12:21AM
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Unit is a TBI going to get ECU unit inder dist cap tomorrow to see if thats the issue

    Bookmark   November 20, 2009 at 10:51AM
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