Power Wagon problems

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HemiPar

HemiPar

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Good morning all and Happy Valentines Day to all.
My 75 Power Wagon is having starting troubles. It has a 360 electrontric ignition. The issue is this, while trying to start it turns over very well, but will only tries to start as I release the starter and goes to run position. So it is very hard to time it right to get it started. I can't think of what may be causing this. Can you guys help me figure this out. I remember reading about this but can't find it. Thanks for any help I can get.
 
kinda sounds like ballast resitor if so i dont think it would start at all or the starter is takeing all the power from the ignition
 
check or replace these components starting with the ballast resistor. i keep extras around for that very reason.
 

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Yep, ballast resistor has burned out on the "Start" side.

When cranking/starting, the ballast resistor supplies 12 volts to the coil, for hotter spark/easier starting. when you let off the key and it's running, the truck runs on the other side of the Ballast instead, which only supplies 6 volts to the coil.

If one side or the other burns out, you'll either have a "starts when you let off the key" or "only runs while cranking" condition.

Edit.. that might be a bit off, I just stopped to think about the ignition on my D50... the ballast supplies 6 Volts on both sides (double pole ballast resistors), there is a 12 volt bypass wire that supplies 12 volts to the coil (from the starter relay, i believe) while cranking.
 
i had that problem on my 69 powerwagon for a while, found a bad connection at the dizzy. the wires had broke inside the insulation where the wires come thru the dizzy case.. pop the dizzy cap off, put your ohm meter on it and wiggle the wires inside and outside the dizzy.
 
My Dart does that when it's really cold out, but still starts while in the start position sometimes too.
Nothing wrong with my balast resistor either, just a spark that isn't hot enough while the starter is cranking the engine when cold.
Only way around it is to do an HEI or aftermarket, from what I have seen.

My car starts really easy too, so about 2 seconds on the key and then let it go and it fires right up so it not a big deal.

Wish yours was that easy.
 
Had the EXACT problem on a challenger a while back, and the brand new parts store ECU was the problem, replaced with NAPAs Echlin brand, problem solved. Make sure the ground is good on the ECU as well!
 
That's the opposite of a ballast resistor problem. When they go bad, the engine will fire up in the "start" position but then die when the key is in the "on" position. Do you have the factory Mopar electronic ignition? 4 or 5 wire control module?
 
Look at the 4 wire resistor diagram. In "start" the RUN wire is DEAD. The only power the system gets is from the (normally brown) coil resistor bypass circuit, which feeds the coil +, and BACKWARDS through the resistor to the ECU. If the one side of the ECU is bad, it won't fire.

I don't believe the 4 pin ECUs suffer from that problem

So it could be a bad resistor if it's a 4 pin resistor / 5 pin ECU, or it could be a bad circuit in the brown start/ bypass.

This is a special, SEPARATE contact in the ignition switch, and the brown goes directly from the IGN switch, out the bulkhead connector to the coil+ side of the ballast.
 
Thanks for all the info guys. It is the factory electronic egnition for a 75 PW. Guess I will start by checking for loose/broke wires. I have an exta ECU so I can switch them out. And if that dont fix then replace the resistor with my spare. It's great that have 2 vehicles that have a lot of same parts.
 
Thanks guys. I replaced the ECU with the spare from the Swinger. It starts and runs great.
 
Thats great!! just what I figured, some ECU seems to be sensitive to low cranking voltage, others dont..
 
replicaracer43 said:
Had the EXACT problem on a challenger a while back, and the brand new parts store ECU was the problem, replaced with NAPAs Echlin brand, problem solved. Make sure the ground is good on the ECU as well!
Click to expand...

Twenty years ago I worked at a NAPA store, and you don't want to know the number of Echlin replacement Mopar ECUs that we sent back as "defective". I remember one customer who went through three in less than three months, and the store manager refused to warranty the ECU anymore, insisting that there had to be something wrong with his truck wiring. I told the irate customer to meet me at home that evening, and gave him a good used factory unit. A year later he still had no problems. That experience spoke volumes to me about the worthlessness of aftermarket replacement electronics. The only manufacturer of an ECU that will ever be on one of my vehicles is Mopar. Rant over.
 
Ok, sorry you had problems, I have used Echlin ECUs for 20 some odd years, and never had a problem...Oh, but I did have a chrome box fail once....
 
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