86 B2000 Ignition Problem

I have recently been having problems with my ignition switch where the contact opens up and the truck dies. Twisting the key slightly seems to cure this and since it has not happened that often I did not follow up on this. This morning the truck died again but I am not sure if this time it is the ignition switch related. The engine cranks but will not turn over. My initial thoughts was that it was spark related. I removed the closest spark plug, stuck a screwdriver in the ignition plug wire boot and held it close to a ground while the engine was cranked. A strong spark could be seen. I did notice that there was a small cable running from the coil to what appears to be a camshaft sensor, small black cube (3/4" x 3/4" x 1/2"), bolted near the distributor and the insulation on the wire near the potted sensor was frayed but not broken. Where exactly is this sensor supposed to be positioned? While attempting to adjust this sensor, the last couple of intact strands of wire broke, unfortunately right at the sensor body which makes splicing this difficult. Anyhow, I would like to know if any of this is related to the failure to start. I had replaced the ignitor in the distributor several years ago and experienced similar symptoms, but I do not remember having a spark at the ignition wire when trying to diagnose. I have checked the fuel filter but do not suspect this is the problem otherwise the engine would have coughed while cranking. I will squirt some starter fluid into the carb to see if I can get the engine to cough. This may give me a clue that the problem is with the fuel pump or perhaps the carburator but I still suspect that the problem is electrical related. Does anyone have any suggestions? It almost seems as if the circuit is grounded but I don't think I would have received a spark at the plug wire if this were the case.

Solution Found - Confirmed it was not electrical by squirting starting fluid in carb and getting the truck to cough a few times when I cranked. This confirmed my suspicion that it was not electrical related. After pulling the hose from the fuel pump the carb, I confirmed that gas was not being delivered. I put a vacuum pump on the disconnected hose and confirmed that there was no plugging. Picked up a replacemenet fuel pump for $23.00 (actualy free since the one that was installed 5 years ago had a lifetime warantee) and installed in about 30 minutes. Also had to fiddle with the wiring harness to the ignition switch and secure it in a certain position using a wire-tie to keep circuit from opening. Also resoldered the broken wire at the sensor. Still unsure what this does since it did not seem to have any influence on the way the engine runs.

Odometer now at 135,000. Looking forward to the next 100,000 miles.