First of all, get rid of any electrical tape. That will unravel into a gooey mess on a hot day. The only proper repair where moisture can get in is to slide the wire strands together, (don't twist them like when using wire nuts in house wiring), solder them, then seal them with heat-shrink tubing. For outside the cabin, use tubing with hot-melt glue inside to seal the joint. All auto parts stores have it.
Second, at any time did you remove the crank sensor? If you did, the air gap when reinstalling it is critical. New sensors from the dealer have a thick paper spacer stuck on the end to set that gap. It slides off and is lost the first time you crank the engine, but by then its job is done. To reinstall that type, get a new spacer from the dealer's parts department. Many aftermarket sensors have a thin plastic rib molded on the end to set the gap. To reinstall those, you are to cut the remaining part of the rib off, then use a paper spacer.
I replaced thirteen transmissions while working at the dealership in the '90s. At first I cut those spacers in half so I could save a few pennies. After a while, I thought I was smarter than the engineers, and I just shoved the sensors in all the way, then pulled them back about 1/16". I got away with that on a couple, but the last one developed an intermittent stalling issue that turned into a no-start. Since the owner had no knowledge that the sensor was involved with the recent transmission replacement, he didn't share that with the next shop, so they misdiagnosed it as a bad sensor. Had they known it was recently removed, they may have just rechecked the spacing first.
Next, the Engine Computer turns on the automatic shutdown (ASD) relay for one second when you turn on the ignition switch, then again during engine rotation, (cranking or running). The fuel pump will run for that initial one second. That is why you see fuel pressure at the rail. What is important is if that relay is turning on again during cranking. If it isn't, you won't have power to the fuel pump, AND you won't have spark. To check if the ASD relay is turning on, measure the voltage at the ignition coil, any injector, or either small terminal on the back of the alternator. A test light works better for this than a voltmeter because it's easy to see when working by yourself. You'll see it flash on for one second when you turn on the ignition switch, and you may hear the hum of the fuel pump. If it doesn't turn on again during cranking, recheck the wires and air gap for the crank sensor. If it does turn on solidly during cranking, you have a spark OR a fuel supply problem.
On newer cars that wire to check the voltage on is usually dark green / orange. I can't remember the color on a '93 truck, but it will be the same color and stripe at every injector and the ignition coil. The same color wire feeds the 12 volts to the alternator, but because of the black rubber terminal block, you can't tell which wire goes to which terminal. The wrong terminal is still a valid test point because while its voltage may be less than 12 volts, it still will only be there if the right terminal is getting voltage. Those are my favorite terminals to use because you don't have to back-probe a connector and wonder if the probe is making good contact with the terminal. Never, ever poke a hole in a wire to take a reading. Moisture WILL get in there and corrode it.
Tuesday, November 26th, 2013 AT 2:59 PM