Back in early '91, we soon experienced the dreaded "no start" condition after a simple rinsing of our engine. After diagnosing the cause of the problem, the Registry provided a means with which to contact many owners before they too made the mistake of bathing their engines.
Simply put, if you wash your engine, you will almost certainly damage the starter motor which lies beneath the plenum in the valley of the engine. This condition seems to be more frequent when the engine is hot rather than on cold starts. There is a small drain tube designed to drain excess fluids from this area, however, in a very short period of time, debris causes this to cease functioning. There is a larger tube kit available which requires drilling your block, however, we found that simply keeping the hose far away from the under hood area is usually adequate to solve this problem.
Other occasional no start conditions can be attributed to a faulty clutch switch, VATS (Vehicle Anti Theft System) key cylinder, or ignition switch. A simple test to determine which may be at fault is to attempt to "jump" start your ZR1 when you experience this problem. This is best accomplished by parking on an incline, then turning on the key to the "On" position. By rolling the vehicle to a fast walk speed, then letting out the clutch in second gear, the engine should fire up. If no signs of starting occur, then the problem is most likely VATS related. If the vehicle does start, the problem is in the starting circuit, i.e., starter, clutch switch, etc.
Note: The ZR1 will likely not push start when the battery is completely drained. It should be at least partially charged first.
Second possible issue:
The true bottom line is that the starter solenoid on these cars requires near new battery capacity. The most common no-start condition is that the solenoid does not engage the starter. If your starter engages, engine turns over but the engine does not start, that is a completely different problem. I'll repeat what I have discovered. There are (unfortunately) a series of voltage drops in the starter (solenoid) circuit. Theses include the starter relay ( under the dash ), the clutch switch, battery internal resistance, battery connections and the actual positive batt (purple wire) attachment to the solenoid.
Since the LT-5 requires optimum power delivery to the solenoid, high resistance in any of the above mentioned areas can result in a no-start condition. To eliminate all of the arcane segments of the system, simply locate the large purple wire in the wiring harness (behind/next to the ECM in the engine compartment), place the car in neutral, apply the emergency brake, turn on the ignition key, pierce the insulation of the purple wire, and jumper/connect a jumper wire no smaller than 16 gauge from the exposed copper conductor of the purple wire to the positive battery terminal. If the solenoid doesn't engage, be sure that the battery is at full charge. You should see a spark at either the purple wire or + batt terminal when you make the connection. No spark... probably an open circuit, spark but no start... possibly a low battery.
Start... install a start switch in the cabin that bypasses all the resistive areas.
-- James Brit