94 Chevy Truck fuel problems

How old is the fuel in the tank?

Check your fuel pressure at the TBI if you can get ahold of a test gauge. If it's good, your injectors may be gummed up from sitting and not opening when they should. One other thing that may be causing the problem is if your ECM doen't know the engine is turning and will not deliver fuel. The ECM recieves this information through the ignition module in the distributor.

So, Is that a two part ignition module? One to run the engine and the second to feed the ECM info. ?

There are conditions when timing advance is controlled by the Ignition Module but otherwise the ECM. Either way, the ECM must recieve reference pulses from the distributor.

"jdpolk" wrote in news:hkQCh.444$ snipped-for-privacy@newsfe04.lga:

are the injectors pulsing?............kjun

There isn't any fuel coming out of the injectors. I can manually pop the injectors, but the ECM isn't sending them the signal to open.

You need to check for spark with a timing light or spark tester.

If gone or erratic....perhaps an ignition module.

skimmer

. I can pour gas down the TB

I'm guessing that if the truck runs with gas poured down the TBI, that it rules out mosy ignition issues. If the pump runs, and the filter's clear, I would CAREFULLY crack lines both at the outlet of the filter and at the TBI , one at a time, then turn the key on, and check to see fuel being delivered, if the fuel is up to the TBI, then it's an injector issue or clog between the fuel inlet and the injectors.As one of the other posters asked, how old is the fuel? Old fuel will gum up after time, and will block small passages, like injector tips. Did I mention CAREFUL? please don't burn down your truck.

Ed

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Likely not a bad idea to rebuild the TBI. If you know that the ECM is not pulsing the injectors (remember the ECM grounds the injectors, the injectors have 12volts at them any time the ignition is "on") take the ignition module out of the distributor and have it checked. You need a special tester to do this, a GM dealer should have one. If you want just change the module, they're less than a hundred dollars for one. I had the same problem with my truck two months ago and that's what the problem was, after the new module, everything has been fine.

That is on my next "to try" list. I think a 20oz drink bottle and a piece of fuel hose put over the fuel outlet should catch most of the fuel. I'm sure that it is time for a TBI rebuild or what ever is done to them.

This sounds like the ECM isn't receiving pulses from the ignition module due to either a bad ignition module or broken connection between the module and the ECM. Without these pulses, the ECM will not pulse the injectors or take over the timing.

Ed..with all due respect you could be right on this but that was not the case with my 93 and some others who have posted in this thread. My engine would crank and crank with no fuel pulses and crazy flashes on the timing light. During the crank mode (less than 400 rpm) the advance etc is controlled by the ignition module not the ECM. If I sprayed some ether in and could catch just of few fires in a row to kick it around it would run. So I suspect (BUT DON"T KNOW FOR SURE) that the low rpm portion of the module is out....if not the entire thing. If he is not getting PERFECT spark when cranking, he should change it. If is getting perfect spark, he should NOID light the injectors and test the pump.

skimmer