So.. I thought I was good, but after driving around all day pulling the trailer, I parked it and 2 hours later it wouldn't start.

I started troubleshooting, but it's been a long while since I've worked on an older vehicle.


I'm not getting any spark. I pulled the distributor cap to check the points and it turns out I have a later distributor with an induction pickup, so nothing much could happen there. I checked the voltage to the coil with the key in the run position and I'm getting weird voltage readings. Anywhere from .6V to 6V, none of which seem right to me. I would assume it should have 12V across the + and - with the key in the run position.

I have a manual and I've been scouring over the wiring diagram and out of reluctance of diving into wiring, I went ahead and replaced the coil and the ignition module.

Still no fire. It turns over fine and I'm getting fuel, so I guess after replacing those two major components, it's down to a wiring issue.

My diagram shows + going to an EGR system and to the starter solenoid. I'm going to jump that wire next to eliminate the wiring between.

The - goes to the ignition module, with the other wires going to the distributor (3ea), the alternator regulator (1) and the last to the solenoid and the neurtral safety switch, which is obviously not in commission.


Any thoughts here guys? I need this thing back on the road as I'm supposed to leave Saturday morning on a cross-country trip.

I guess better now than in the middle of nowhere... but I'm out of ideas at the moment.

 

If anyone knows ways to bypass certain sections of wiring, please let me know.


I ran a jumper from the + to the solenoid and still nothing.

Any chance the solenoid could be bad? I mean it turns the motor over, but could the other connections go bad? It seems pretty unlikely, but I want all options.

 

You won't see 12 volts across the coil. In fact it's not a valid measurement to measure across the coil because the negative terminal is switched between ground and open-circuit, which is how the module fires the coil.

If the motor is turning over, the solenoid is fine. Try disconnecting the distributor, and measure the resistance between the ORANGE and PURPLE wires coming from the distributor. You should see between 400 and 700 ohms.

 

The wires coming from the distributor are color coded differently, but the orange and purple coming from the ignition module is showing 727 ohms

 

Here's a view of the diagram from Haynes.




Any other ideas on this? Since I guess I shouldn't see 12v at the coil, we're back to it being pretty much anything.

 

Well... the GOOD news is, it's running!!!

The REALLY BAD news is... I have no fricking idea what the actual problem was. I connected and disconnected so many wires and things, I think I caused another issue, fixed the original issue (coil or ign box), then fixed the problem I created....


The other GOOD news is that I've become very intimate with the entire electrical system now...


Anyways, it's running good, but in the process I found out my distributor hold down bolt hole is stripped. I laced the heck out of the distributor for now, but I need to get that fixed... That's all I need is the sucker advancing or retarding to detonation while pulling a trailer...

 

I just solved my no start problem earlier this week. The pickup in the distributor was bad. When cold the truck would start fine but after my 20 min commute the truck would shut down at slow speeds and not start back up. The pickup inside the distributor was getting hot and the resistance increased bad enough to not work.


My book says to check the two pararellel metal contacts coming from the distributor. (there are three contacts sticking out; one horizontal and two parallel) My book says they should read between 400 ohms and 800 ohms. My bad one was reading ~900 ohms. With the new one in the truck it was again reading ~640 ohms. Been driving all week with no problems!

If yer going on a long trip it would hurt to have a spare distributor pickup with you. Mine cost $14 at OReillys. Good luck.

 

Thanks for the advise!! It really wouldn't hurt to have a spare everything on a 34yr old truck driving cross country!!! LOL!!