Help! Truck won't restart once hot.

[thatK30guy]

Truck is an '85 M1008, bone stock, with the 12 volt conversion.

I can start it up and do short trips to town, etc. and shut it off. It will start back up immediately.

But if I do a longer trip or let the truck get completely warmed up to normal operating temps, then shut it off, all the electrical and gauge lights go completely dark. No power to nothing.

Let the truck sit for about a week or two, then turn the key on, the lights on the dash come back on and the truck is ready to fire up.

I know its an electrical gremlin somewhere but has anyone else experienced this problem with theirs? Maybe its something to do with the conversion?

Help! I need to use this truck and don't want to be stranded 40 miles from home. What gives?

 

[scottystills]

I had some ridiculous electrical problems on my truck when I first got it. The PO had done a bunch of "custom" touches behind the dash. One of the most frustrating was similar... Sometimes the truck would start right up, sometimes the lights on the dash would come on but flicker like crazy when I hit the starter.

As far as root cause, no idea. There are too many places you can have the problems. What I ended up doing was pulling the starter to snug up all the connections. At the same time, went and made sure that my grounds were good on the block and on the body. Also don't forget to check that the dist stud on the firewall is good and tight where the power comes up from the starter.

If you've done (or the PO) the 12V conversion on an M1008, make sure that any point connections that were affected are good and tight.

My thought would be that when it's heading up and metal expands some of your connections might be coming loose.

Do you need to leave it for 2 weeks, or is it operating normally as soon as it cools back down to ambient?

 

[thatK30guy]

If it gets warm or hot enough after driving it long enough, and it won't restart, I've checked it each day to see if the dash lights come back on so it'd be ready to fire up again. This could be on average up to 1 week, sometimes 2. Then the lights come back on and its ready to fire up. So I'm guessing its cooling off during this time.

Sounds like I'm gonna just have to crawl all over the truck and check all the fastening points. I had wondered about the starter if those wires were loose, too. Just didn't know if anyone else had problems with their M's or diesels.

 

[scottystills]

Ya mine did it enough times (and got a sore neck pulling the starter enough times) that I finally threw a lock washer on the main post. Been tight ever since.

 

[Massboy]

Check the 10g wire that runs from the firewall terminal group (by the batteries) to the small black diamond shaped 2 terminal block on the firewall mounted up high near the location of the hydra boost. I've seen these wires break internally (inside the insulation) and get hot causing them to basically lose conductivity. My M1009 drove me crazy. That red wire also has a larger than the wire black resistor on it (about 3/8's in diameter, 1" long) and that can open too. Not sure if it's your problem but it was with mine. Never took as long a 2 weeks but sometimes a couple days. Found the issue with a continuity meter.
Good luck.

 

[86454K30]

Also check the ring terminal on the back of the alternator. I had one that looked fine, tested fine and once it got hot it would loose connection. It would kill the dash lights, make the stereo pop and when it got bad it wouldn't restart. I put on a new ring terminal and bam no more problems!

 

[scottystills]

Get the kinks worked out?

I'm always anxious to see people's fixes on these damn things, make sure I know how to fix it when, not if, it ends up happening on mine.

 

[thatK30guy]

Not yet. Haven't found time to touch it. Just got back from a weekend with the lady in Missouri. Pooped out if you catch my drift.