I have a 1988 5.0L E-150 Van with 170K miles, which WAS running great. I replaced a busted heater core hose and now it won't start. It cranks good and strong, but shows no sign of firing (no smoke, no knocking, nothing). I removed and verified that the sparkplugs are firing. I opened the fuel line just before the block and verified that I have fuel to the engine. (When I try to start it, there is no noticeable fuel odor.)

I suspect the injectors. I really don't want to rip out an injector to check the mist, because I am convinced it is wiring. Here is why... After I reconnected all the heater hoses, and it wasn't starting, I noticed a loose connector hanging beside the alternator. This connector looks very clean, and is located near the area where I replaced the heater hose. So, if figured I must have pulled it loose (eventhough the holding latch is intact).

This connector is 2 wires, red and gray/ylw, and is about 12 inches long. It comes out of a main harness, behind the alternator (which is on the passenger side of the engine). I only have a Haynes manual, which shows that Gray/Ylw goes to the Oxygen sensor. So I don't really understand why that would keep the engine from running. I totally removed the alternator and hoses, searching for the connection point. I could not find anywhere to plug it back in.

Here is what I am looking for.
Is this connector the problem?
Where is it supposed to connect?
Can I safely jumper it together to see if that solves the problem?

If this connector is an "extra" and is unrelated, how can I check the injectors? I would like to check the pulsing without removing them, if possible.

Thanks for any help.