92 305 TBI Intermittent Fuel/Firing
 

Just looking for some advice here. I have a 1992 Firebird 305 TBI which is intermittently starting. A few weeks ago I went to take it for a cruise and got the security light and the usual nothing when you try to start. No big deal, came back a couple hours later and the old bird starts right up. Not a single issue since then and I've driven it six or seven times (every couple days). Yesterday I took it for a drive down in Colorado, about a hundred miles non-stop driving in 80 degree weather. Nothing happened out of the usual, fuel, oil, engine temp all normal, stop at one store and do a little walking around get back in and start cruising. Not even fifteen minutes later, stop to get gas and use the restroom. Here's the problem, get back in and the car cranks but doesn't fire. Spark is there since it catches a little bit when fumes build up from heat but soon dies out since no more fuel is being delivered. Fuses for injectors all good, fuel pump replaced less than a year ago with maybe 1,000 miles on it (happened late summer so it was replaced then put up for the winter). Payed for a two hour tow home. Go to push it from the street side into parking space. Figure meh what the heck, and it starts first try. Needless to say I'm kind of angry and confused, can anyone shed light on what could cause this?

TLDR: Drove for a few hours, stopped, started and drove fifteen minutes, stopped, will not start (cranks but no fuel). Newer fuel pump (as in less than 1000 miles).

From what I have gathered myself it could be fuel pump realy or ICM? Let me know what you all think would be a good starting point.

Re: 92 305 TBI Intermittent Fuel/Firing
 

I'd start by checking for trouble codes, then measure the resistance between terminals on the fuel injectors.(Un plugged of course) If they are not in spec, they can shut down all injectors from firing.

Are you also having a " crank-but-no start" , issue? That would be battery/starter/alternator/related wiring issue.

Re: 92 305 TBI Intermittent Fuel/Firing
 

Security light is probably the VATS, can be intermittent. Have bypasses for that. The crank - no start could be an overheated ICM. They can be real picky when not to start. Pull it and have it checked out for free at Autozone or other parts store.

Re: 92 305 TBI Intermittent Fuel/Firing
 

I appreciate the responses. I will get a bypass on order because I just don't want the risk of it acting up. I will check error codes, the ICM, and injectors as well for good measures.

Re: 92 305 TBI Intermittent Fuel/Firing
 

Judging by the description, you're GUESSING that there's no fuel delivered. You haven't connected a pressure gauge to verify intermittent lack of fuel pressure, you haven't SEEN the injectors fail to spray. You haven't gotten the engine to start by supplying fuel manually--pouring a drizzle of gas into the throttle body.

This could just as easily be a distributor failure, where both the spark and the fuel spray are intermittent.

"I" would want to know
Fuel pressure
What voltage the fuel pump is getting when the engine does run? Can't measure voltage inside the tank, but you can measure voltage at the harness connector just before the wires go between tank top and floorpan. Voltage must be measured as close to the fuel pump as practical.
How much voltage is on the ground side of the fuel pump wiring? Again, gotta measure as close to the fuel pump as practical.
How old is the fuel filter? Was the filter sock on the pump replaced when the pump was replaced? Did you also replace the in-tank wire harness that so often corrodes?
How old is the distributor pickup coil?

If the VATS is goofy, FIX THAT FIRST.

Re: 92 305 TBI Intermittent Fuel/Firing
 

I agree with previous post - you need to verify fuel pressure. I posted on another thread on how a ruptured inlet hose caused a very similar problem.