71 440 engine fires but doesn’t stay running

[Bee1971]

Is your wire for electric choke going to the positive side of ignition coil ?

If it is , disconnect that positive wire to electric choke for now and see if it starts and try’s to stay running

I am confused with your readings at ballast resistor


With key in run position

Do you have any VOLTS at positive side of ignition coil

 

[R413]

The wire harnesses they make with electronic wired into them is for a dual ballast.

 

[BLK 68 R/T]

Good thought. Where would be the best place to wire it to?

A key on 12v source. Acc. Spot on fuse box? or any other key on 12v, that’s not part of the ignition circuit. You don’t want 12v all the time, just when the key is on.

 

[BigRedClone]

On electronic ignition, it could be bad magnetic pickup.

You mean in the disti? That and the coil are the only 2 things in the whole compartment I haven’t replaced. Might swap it just to rule it out. Good thought!

Is your wire for electric choke going to the positive side of ignition coil ?

If it is , disconnect that positive wire to electric choke for now and see if it starts and try’s to stay running

I am confused with your readings at ballast resistor


With key in run position

Do you have any VOLTS at positive side of ignition coil

Bee1971. Electric choke disconnected. Awesome. Ok. key in ‘run’ position. Probe to the neg battery and positive on the Ignition coil I have 5.6v.

 

[BigRedClone]

I'm thinking ballast resistor also.

gkent, r413, and 493 Mike, swapped the ballast resistor and it fired and ran for 15 seconds and then died. BR taken off and tested fine. I think it’s going back to the bulkhead connector as Bee1971 said. I just gotta learn some basics of a test light. I’m a helluva part swapper. Electric diag is obviously not my strong suit. ‍

 

[dadsbee]

Just take a wire direct from battery to the run side of the ballast wiring. Hit the key and I bet it runs, then work backwards to find the failure point.

 

[BigRedClone]

Update. New coil and distributor. It fired up and ran smoothly for 5 minutes. Idled perfectly. Then died. Can’t get it started and have a half tank of gas. Anyone know any cliffs close by? I think it needs flying lessons.

 

[BLK 68 R/T]

Update. New coil and distributor. It fired up and ran smoothly for 5 minutes. Idled perfectly. Then died. Can’t get it started and have a half tank of gas. Anyone know any cliffs close by? I think it needs flying lessons.

do you have spark?

 

[LowBikeMike]

Likely the parts replaced had no impact, but moving the wires around during the process got it to run, then the bad connection reappeared. Quit replacing parts, you've got a wiring issue.

 

[dadsbee]

Update. New coil and distributor. It fired up and ran smoothly for 5 minutes. Idled perfectly. Then died. Can’t get it started and have a half tank of gas. Anyone know any cliffs close by? I think it needs flying lessons.

Did you do as I suggested in post #26..

 

[LowBikeMike]

Unwrap the wires that are resting on the passenger head and look for damage, based on their routing likely to find a burn wire.

 

[BigRedClone]

Did you do as I suggested in post #26..

Dadsbee.. yes. Just did it. Wire from the Pos to the ‘Run’ (or left side). Put the key in ‘run’ and jumped it. Tried twice. Then a little brake cleaner as motivation down the gullet, and it fired up and ran. I let it run for 3 minutes. Turned it off, removed the jumper wire and turned the key. Fired up and ran. 5 more minutes running smooth. I turned it off and turned on again. Success. Waiting 20-30 minutes and tried again. Success. Now my paranoid brain thinks it’s going to be an intermittent issue. So I’ll turn it on and start wiggling stuff. I wish I could put my finger on the ‘bad part’.. but electricity is still voodoo to me. Thank you guys for your guidance. I appreciate it more than you know.

Eric

 

[BLK 68 R/T]

Be

Dadsbee.. yes. Just did it. Wire from the Pos to the ‘Run’ (or left side). Put the key in ‘run’ and jumped it. Tried twice. Then a little brake cleaner as motivation down the gullet, and it fired up and ran. I let it run for 3 minutes. Turned it off, removed the jumper wire and turned the key. Fired up and ran. 5 more minutes running smooth. I turned it off and turned on again. Success. Waiting 20-30 minutes and tried again. Success. Now my paranoid brain thinks it’s going to be an intermittent issue. So I’ll turn it on and start wiggling stuff. I wish I could put my finger on the ‘bad part’.. but electricity is still voodoo to me. Thank you guys for your guidance. I appreciate it more than you know.

Eric

Be careful with brake cleaner down the gullet. You’ll wind up dead. Being totally serious.

 

[BigRedClone]

Be

Be careful with brake cleaner down the gullet. You’ll wind up dead. Being totally serious.

Appreciate the heads up. I sold brake/carb spray (as well as detail supplies) for a decade to shops and stealerships. Knowing that carb spray isn’t flammable but brake spray is is like knowing a tomato is a fruit, but you don’t use it in a smoothie. Just a spritz does the trick. Any more and unintentional spontaneous disassembly is a real possibility.

 

[BLK 68 R/T]

Appreciate the heads up. I sold brake/carb spray (as well as detail supplies) for a decade to shops and stealerships. Knowing that carb spray isn’t flammable but brake spray is is like knowing a tomato is a fruit, but you don’t use it in a smoothie. Just a spritz does the trick. Any more and unintentional spontaneous disassembly is a real possibility.

Not a danger of spontaneous disassembly due to too much spray and an explosion. It’s what happens when it combusts and comes out the tailpipe as a different gas.

 

[Geoff 2]

Is it running out of fuel? After it dies, operate the acc pump on the carb & look for fuel squirting from the pump nozzle.

 

[BigRedClone]

Not a danger of spontaneous disassembly due to too much spray and an explosion. It’s what happens when it combusts and comes out the tailpipe as a

Not a danger of spontaneous disassembly due to too much spray and an explosion. It’s what happens when it combusts and comes out the tailpipe as a different gas.

View attachment 1994098

Not a danger of spontaneous disassembly due to too much spray and an explosion. It’s what happens when it combusts and comes out the tailpipe as a different gas.

View attachment 1994098

Once upon a time (1988-91), I repped for MoC Products and that is when the conversion happened from chlorinated to non-chlorinated in CA. Early mixes were like spraying water. Every time I’ve used it, it blasts out the exhaust system like I dumped nitro or something. Even did this time. Some of the old wrench’s I knew blew out rusty exhaust pipes trying to get something brought back to life. But I never knew about the phosgene gas the trichlor would create. Lucky to still be alive I guess. And if it would have known BC was still available on the east coast, I probably would have made a few ‘Smokey and the Bandit’ runs.

 

[1fastrunner]

I'll share what happened to me...
I replaced original harness with same M&H harness and ignition set up from 4secondsflat including curved distributor.
After having similar problems we kept messing with advance and could keep it running "most" of the time, but not good.
Wasted a lot of time and got nowhere.

Long story short, it was the 4 prong ballast.
I switched to the factory recommend 2 prong and left 2 plugs unplugged.
Problem solved.
The resistance was brought up earlier in this thread, that was my problem, hope it is yours and you get it figured out.

 

[BigRedClone]

I'll share what happened to me...
I replaced original harness with same M&H harness and ignition set up from 4secondsflat including curved distributor.
After having similar problems we kept messing with advance and could keep it running "most" of the time, but not good.
Wasted a lot of time and got nowhere.

Long story short, it was the 4 prong ballast.
I switched to the factory recommend 2 prong and left 2 plugs unplugged.
Problem solved.
The resistance was brought up earlier in this thread, that was my problem, hope it is yours and you get it figured out.

Great suggestion! After swapping the remaining old parts (disti and coil) and giving each connection a jiggle, it fires right up. Runs smooth.. shuts down and fires again. Next test is wiggling connections while it’s running. Then I take the leap of driving around. We’ll see.