First some background for those interested....
I've been having intermittent no-starts for last couple weeks and now truck won't start at all. Did some troubleshooting and it seems I'm getting fuel but no spark. I'm fairly new at this so please correct me if I've drawn incorrect conclusions. Its a '94 D-90 3.9 V8 with factory distributor and coil (i think), amp module was relocated two years ago. I pulled the plug off the center of the dist cap and set it next to engine block, operated the starter and got no spark at all, until i turned the key off then got one small spark. repeated that several times....no spark while starter turning, one spark when turning key off. So i broke out the workshop manual and followed the sequence of voltage drop tests with all connections in normal state. Never used a multimeter before this but seemed simple enough. Voltage across battery measured 12.2 V. Multimeter leads couldn't reach from battery to coil so tested engine block to what i think is ignition switch side of coil and got 11.5 V. Then measued from engine block to other side of coil and got about 5.6 V. From what i could interpret, the book said if that was the case to disconnect the lead on coil that goes to distributor and re-measure the low voltage so i did that and got same reading of 5.6 V. According to manual...refit coil. So thats what I plan on doing....BUT, one other test it had me run was grounding on engine block and touching one of the bolts on the amp module....supposed to read between 0 and 0.1 V. I measured 0.4-0.5 V. So what other conclusion should I take from this? will replacing the coil solve the problem? Is the bad ground on the amp module a possible cause for burning out the coil? If so how do i fix that?
I did some shopping around for new coils...AB seemed to have best prices with cheapest option at $40 then a Lucas for $50 and Bosch for $100. Any suggestions?
Any help is appreciated.