71 440 engine fires but doesn’t stay running

[BigRedClone]

Hi guys. Long time lurker and have learned a ton. But my research has come to a dead end. I have a 71 RR clone with a 440. Fresh rebuild (600 miles on it). Been dialing it in and the engine wiring harness was a rats nest so I swapped it with an M&H unit. Everything hooked up easily. Now I Fire it up and it barks off but doesn’t stay running. At my first attempt, I had the coil hookup swapped and nuthin happened. Swapped them to the correct position and it fires and dues. Was running fine before. Any suggestions or direction would be GREATLY appreciated!

 

[493 Mike]

Does it die as soon as the key is released from cranking position?
Mike

 

[R413]

So it starts and when you release the key it quits? Look at the run side Ballast resistor or wiring.

 

[gkent]

I'm thinking ballast resistor also.

 

[dvw]

Two circuits feed from the ignition switch. Brown wire is hot in crank only. The blue wire is hot in run only. Stock they both feed to the ballast resistor.
Doug

 

[BLK 68 R/T]

I would definitely address your throttle return spring…before you end up at full throttle…

 

[BigRedClone]

Does it die as soon as the key is released from cranking position?
Mike

Yes. Exactly

 

[BigRedClone]

I’ll check that out first thing in the morning. Thanks!

 

[BigRedClone]

I would definitely address your throttle return spring…before you end up at full throttle…

And this is why I posted pics! Thanks for the tip!

 

[BigRedClone]

So it starts and when you release th key ir quits? Look at the run side Ballast resistor or wiring.

Will do. Thanks!

 

[BLK 68 R/T]

How is your electric choke wired in for 12v? I’ve seen those wired into the ignition circuit in the past and it has caused issues.

 

[BLK 68 R/T]

And this is why I posted pics! Thanks for the tip!

Your spring setup should look very close to this.

 

[Dave6T4]

On electronic ignition, it could be bad magnetic pickup.

 

[Bee1971]

What DVW said

Check your run circuit from ignition switch thru bulkhead connector thru Ballast Resistor

Simple test light or volt meter

 

[BigRedClone]

Your spring setup should look very close to this.

View attachment 1990987

Thanks for the pic! That’s what I was looking for.

 

[BigRedClone]

What DVW said

Check your run circuit from ignition switch thru bulkhead connector thru Ballast Resistor

Simple test light or volt meter

Tested the Ohms on the Ballast Resistor. 5.6.. Should be ~1.2-1.5. (I am not an electrical type dude, but my son builds guitar pedals, so I leveraged him). Ordered a new one, picking it up tomorrow.

 

[dadsbee]

You're running a dual for some reason... one side is supposed to be 5 ohms, the other 1.2. Doubt the ballast is your problem...

 

[Bee1971]

Like Dadsbee said - On the 1.2 OHM side of Ballast Resistor , key in RUN position , check for VOLTS at The Ballast Resistor , then VOLTS at the positive side of ignition coil

 

[BigRedClone]

Thanks for the diagram. Came with a dual and the new wiring harness confirmed it I guess. I get 0.0 across the top and 5.0 across the bottom. When I check to the + on the coil, top 2 show 5.0, lower left shows 5.0, lower right shows 0.0.

 

[BigRedClone]

How is your electric choke wired in for 12v? I’ve seen those wired into the ignition circuit in the past and it has caused issues.

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