Good afternoon everyone, Im having an interesting issue here. First, the vehicle is a 1978 D150 Adventurer. 318v8, 727 trans 2x4.

The vehicle sat for a while before I purchased it so Ive been tinkering making all the lights work, gauges, repaired several vacuum leaks etc.

last week after reinstalling the fuel tank, I took it for a spin, noticed a slight hesitation mid throttle other than that it runs beautifully. Turns out the vacuum advance was not functioning. Next day I replaced that and tested it, set the correct gap to .006 and found I had no spark when cranking it over. I orriginally thought I bumped something when replacing the advance. Replaced the pickup coil with a spare I had, no luck. Ordered a new pickup coil and had the same issue. I got it to fire once and was able to drive on the highway with no issues, but the next day no spark again.

Turns out after studying the schematics, replacing the plug wires, cap and rotor, starter relay, ballast resistor, ignition module and ignition switch, it still had no spark. Dug a little deeper into the wiring harness and found the negative wire to the coil had melted and contacted with another wire. After repairing those wires and adding a fresh ground cable it fired up instantly. However after about 10 minutes of idling it just quit, didnt sputter or anything. Just sounded like someone turned the key off. After cranking it for a few seconds it ended up starting when I switched the key back to run. Then shut off another 2 minutes later.

im kind of stumped on this one so any tips would be appreciated. I also noticed this jumper wire the previous owner had pushed into the plug for the ballast resistor, not sure why because its not on the orriginal schematics so I feel like it may be a clue.

thanks everyone

 

There are two circuits to the ballast resistor, start, and run. It looks like one them failed, and that jumper wire was the PO's 'solution'.... Disconnect the wires, and test resistance on both sets of contacts. (they are inline) See what ya get.

 

There are two versions of electronic ignition and you have the 4 terminal resistors so this is how it's wired. The bulkhead connector is notorious for bad connections(mainly the amp gauge) but others can be effected. Make sure you have power to both run and crank.



http://www.madelectrical.com/electri...p-gauges.shtml

 

Ballast resistors on these were bad about failing. I always carried an extra in my tool box wrapped in a towel. The updated resistors use single connections at each end. The dual ballast was done away with. They cut the power from 12 to 6 volts. If it was bypassed, that might be why wires melted.

Do you have the regular or lean burn ignition? Both were used although I think most trucks got the regular because of lax emissions regulations.

 

i dont believe it is lean burn. The strange part is after the last issue of it randomly turning off, I havent had that issue again. I just want to make sure that as I work on it, if I decide to bring it to work which is a 50 mile drive, that I dont end up stranded. Haha I also noticed from testing the negative side of the coil to ground, im getting around 1.5 volts. I believe that should be close to nothing no?

 

Dodge trucks, the 150 and heavier were usually emissions exempt through the 1980's. My '84 W150 was "No Catalyst". Most likely you have the regular electronic ignition. Lean Burn is a box mounted on the side of the air cleaner.

Your brain box may be fried if wires have been melted. If the previous owner ran the ballast bypassed for very long, it may have cooked the box. I've had them fail when hot. Try replacing the controller. It's a cheap part and easy to replace.

https://www.ebay.com/itm/37497294035...3ABFBMvNDQ8vZj


Just make sure the plug is good and the ground where it bolts to the firewall or fender is good.

 

You may want to look at this link and inspect the amp gauge wires/gauge and the bulkhead connectors. My 78 when i bought it (in the 90's) was starting to melt and had burned connections. Most delete the amp gauge and just use a volt gauge.