Hey guys! I'm trying to diagnose a poorly starting / running / backfiring TPI system. Basically the thing will rarely start, and when it does it only runs on a few cylinders, not to mention backfiring and popping at the slightest notion of a load on the engine. Sometimes backfires while sitting there idling.

My first thought is that the backfiring has to be timing. What I was thinking is that the balancer on my engine must not be the correct one. So, I went ahead and tried my theory out, sure enough, the number 1 cylinder stops hissing when the balancer mark hits about 12:00. Now, the reason why I am doubting myself is cause I just pulled that balancer off an 89 Chev 1/2 ton, along with it's timing tab, which I know for sure was accurate.

Now, say that thing is innaccurate, would the ECM have enough adjustablity in it's timing to get the thing to fire at all? Cause it has run with the timing set at 8 degrees initial advance, however suckily...

Or, would my bad injectors be able to cause all of this greif I am having? I know that at least a few of them are bad, as I loose all my fuel pressure within a few minutes of the truck sitting.

The engine is a mid 80's Chevy 350, from a truck, that was bored out .030, has a comp cams XE262-H camshaft that I broke in on a carb (engine ran pretty good carbed), stock rebuild smog type heads with upgraded springs for the cam, and an otherwise stock bottom end. Not a high compression engine, as I have thoughts of mild boost in the future.

 

MAF maybe?

 

Guess I shoulda mentioned that it is a speed density system, and less the injectors, everything else is known good.

 

Not all that much, and its related to engine parameters like coolant temp, vacuum/load, etc.
I'd sort out that base timing issue first and go from there. I've seen cars run with timing way off before, so its possible its running that far off.