I have an RS 305, TBI, that was running fine, until I stopped driving it for about a month. I tried firing it up, but it just cranks, and sputters.

I clearly see fuel spraying from the TBI unit, and I checked a spark plug for spark, which it is.

Any ideas?

I'm not sure whether it's because the car won't run, or not, but it's not throwing any error codes.

One other thing, about a year ago, it was idling rough, and it was giving off an EST trouble code. The voltage on one of the wires of the little four pin connector that plugs into the ICM was low, so I spliced a new wire in, which fixed the problem.

Thanks for the help.

Spark TO the spark plugs is not equivalent to having a spark across the plug electrodes.

First Guess: Fouled plugs.

I'm sorry for not clarifying; I clearly saw the spark jump the gap. Also, we're talking maybe two, or three, weeks of the car not being driven regularly, and going from running smoothly, to not even starting. I don't think fouled plugs could explain such a drastic transition.

Any other ideas?

An engine will run if it has:
1. Compression in all cylinders, 100 psi or more strongly preferred
2. A burnable air/fuel mixture
3. Ignition at the appropriate time
4. An appropriately free-flowing exhaust

You need to figure out which of these you don't have. While somewhat unusual, there can be more than one thing wrong.

You're saying the spark is OK; and there should not have been any disturbance that changed the timing. A weak coil might cause this...but I don't know why it would have died while the car is in storage. The plug can fire in atmospheric pressure, but not when subjected to 150 psi of engine compression.

A plugged exhaust would still allow the engine to fire a time or two, even if it didn't run long. Might be worth looking for bird nests or a dead squirrel in the tailpipe...but that's kind of a long-shot.

There shouldn't have been a change to the cylinder compression while the vehicle has been in storage.

I'd take a fuel sample and see if it burns, before doing deeper investigation into the other three items.

Had similar issue a couple of times. This only happened when I removed and re-installed the air cleaner to work on heater hoses, distributor cap replacement and on AC. As suddenly as issue began, it stopped after I wiggled all the wires behind the air cleaner (coil, EGR Valve and solenoid, connectors into the module located under the distributor cap) etc. Maybe that module is the one giving you problems. I have gone through about 5 in 20 years in my '89 Firebird. What is frustrating is that since I do not know what caused it, it may happen again.

Two biggest things that kill the module in the distributor:
1. Failure to install module with proper heat-sink compound between module and distributor body

2. Ignition coil that has partially-shorted, reducing primary resistance and therefore drawing excessive current from the ignition module. The HEI ignition coils already have fairly low resistance (typically about 1/2 of one ohm.)