The first two places folks tend to start with a "no start" condition is the basics: Fuel and Spark.
When the no-start condition is present, is there spark? Yes? Check fuel system / injectors. No? Diagnose Ignition System. You could even spray some starter fluid into the intake while the engine is cranking to see if it lights off. If so, you have a fuel delivery issue. If not, check spark.
When I had a strong "raw" fuel smell from my T/A, it took a while to track down, but I eventually found it. ...under the driver side door the steel fuel lines connect to the Nylon (or whatever they are) fuel lines that run into the engine compartment. 2 are a proper mechanically coupled connection, the other one just uses a rubber fuel line as the coupler. The rubber perished on mine and allowed the fuel vapors to escape to atmosphere. I used 2" of scrap fuel line from my lawn mower in it's place. Problem solved.
The fuel pressure test and observations are important. Engine-off/key-on, it may point to a weak pump, leaking injector(s), etc. Things could also be fine on startup, but at the 20 minute mark you notice fuel pressure fall to ZERO as the engine stalls, and then the pump will not prime again until time passes; and it cools down. ...indicating a "thermal" failure with the pump itself or maybe even the relay.
That said, you might have TWO unrelated problems.
Maybe it's not the fuel system at all, and the fuel smell isn't even related. Maybe it is
the fuel system and the smell isn't related...
The ICM has a hand in spark control and is prone to Thermal Failure (after a reasonable service life) due to it's location. It's like a CPU and has a heatsink. Being mounted on the head, it gets really hot, and electronics can only take so much thermal cycling and/or heat before they let go. The thermal paste dries up with age and loses effectiveness...
A failing ICM tends to make the engine cough and spit a bit before it dies in my experience, and once it start this, it doesn't take long before it's just dead 24/7. Two or three ignition cycles at most after the first failure.
Call your local AutoZones and ask if they can bench-test an ICM, one should have the test equipment on hand. They will probably have to heat it to induce failure if it's thermal related.
Or, you can use the Factory Service Manual (or the directions at SHBOX) to test the ICM and OptiSpark in place as soon as the stall/no start condition appears.
The OptiSpark is the Alpha and
the Omega of the ignition system; and it can fail from thermals too.
Actually, it seems like only AFTERMARKET
OptiSparks fail from thermals. I dealt with this over 10 years and 7 aftermarket Opti's. When my engine got to 160F, it cut off. Dead. No spark until it cooled way down.
There are supposed to be 2 codes for a failed/failing OptiSpark. One code says the high-resolution pulses are missing, this is no big deal, the engine runs fine but can not be timed "as precisely". ...you'd never notice there was an issue if the Check Engine light wasn't lit. The other code, for the low resolution pulse, is major. Without this pulse, the PCM has no idea where any of the pistons are in their stroke. As such, it can't time a spark properly, and could be so far out of time it could damage the engine. ...so the PCM shuts everything down.
Thing is, the aftermarket OptiSparks tend to fail without ever setting a code. They drop their ground apparently, and when that happens, the OptiSpark just "disappears" from the system. No pulses, No codes, No Spark, NOTHING!.
Here is SHBOX's procedure for testing the OptiSpark, and for grins, the coil too:
My first ignition failure was the ICM, but a mechanic said "it's always the OptiSpark when that happens". Opti's were still over $1,200 at GM plus labor so I bought a $500 unit from AutoZone and installed it myself. While the RTV I used was curing, I tore apart the OEM OptiSpark destroying it in the process. Next morning, went to start the engine. NO START! ...this is when I learned of the ICM. Replaced it for $90 and a helluva lot less labor and the engine fired right up. 6 months later, the aftermarket OptiSpark failed. ...and each subsequent replacement failed within 10,000 miles. Always different brands, never a code. Not even once.
Bought a remanufactured OEM OptiSpark almost 10 years ago, never had an issue since. I have replaced the ICM again
though. I'd like to think that if I had never destroyed the original OptiSpark, I'd still have it, and would have just replaced the cap and rotor 3 times now.
Point is, do the diagnostics. Even if the fuel smell is actual flooding, you need to know why. Excessive fuel pressure, leaking injector, etc.
is expensive, and in today's times, the replacement parts likely aren't as good as the near 30 year old parts you'll replace needlessly as you play parts-roulette. As the old saying goes, "If it ain't broke...".
Let us know where you're starting from. Lack of fuel or lack of spark. When you know that, you're on your way to resolution.
If you don't have a multi-meter, now is the time to buy one. Anything around $10 is just fine.
...and if it hasn't been offered yet, member GaryDoug has scanned most of the Factory Service Manuals and provided them to us. It's a great asset. You will need Adobe Reader to search through the document as it's several thousand pages long; and worth it's printed weight in Gold.
The '96 Manual is there. Grab it!
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