won't start!

I have a 1986 240DL that just quit one day. I believe it is a wiring problem having something to do with the starting mechanism. I am not a mechanic, but have had 2 go over the wiring harneses, starter and everything they could think of associated with them. Couldn't find a reason. Neither was a volvo specialist though, and I wondered if there was a quirky thing that had to be connected/disconnected for the engine to start? This all happened about a year ago, stopped at a gas station and never got going again. No signs of trouble before hand, (though a similar incident occured once before on a road trip and the mechanic put a few bits of tape on various parts of the wiring harness, charged an absorbetent amount and off we went). Any ideas where to look for the problem?

(1) Open hood, look for wire connector.(on firewall top- middle)...CAREFULLY peel back "tape" cover and check if wires are damaged/crumbly (2) check injection/pump relay( inside auto,right side) (3) get a "CHILTONS" or other brand manual to assist you. These two problems are a real pain. If they check OK, post again with more info. PS don't try starting it again before you get that old stale(year old)gas out of the system...that could mess up your injectors! Good luck