Won't run when warm

[edwjmcgrath]

You may be right, but i've seen my share of both-total failures and intermittent, heat sensitive failures. Probably has to do with where and how the coil fails. In any case, if the engine won't start, it should be pretty simple to distinguish between lack of fuel and lack of spark.

Pull the air cleaner and operate the throttle-you should see a good strong squirt from the accelerator pump.
Pull the coil HT wire (or a plug wire) and place it near a good ground point-then crank. You should get a good blue spark.

 

[miker]

any update?

 

[Tireguy87]

any update?

Picked up a ballast resistor today. Now I'm no electrician so I'm going to need some guidance here. How do I go about wiring this in?

 

[edwjmcgrath]

To keep it simple, the wire from your ignition switch goes to one end of the resistor, and the other end of the resistor goes to the coil positive. Try that and see how it goes.

If that solves your problem, then you might want to consider running the wire from the starter to the coil positive. That might give you a hotter spark while starting.

 

[skidplate]

I'm a visual guy, so I hope this helps. At least this is the way mine is wired, and it works. ( 1975 2F federal model)

 

[Tireguy87]

To keep it simple, the wire from your ignition switch goes to one end of the resistor, and the other end of the resistor goes to the coil positive. Try that and see how it goes.

If that solves your problem, then you might want to consider running the wire from the starter to the coil positive. That might give you a hotter spark while starting.

Sounds easy enough. I'll get on that and report back. Does it matter where I mount the resistor?

 

[edwjmcgrath]

It's not really critical, but the resistor will generate some heat, so mounting it on something metal to dissipate the heat would be good. Not the exhaust manifold tho.

 

[Tireguy87]

It's not really critical, but the resistor will generate some heat, so mounting it on something metal to dissipate the heat would be good. Not the exhaust manifold tho.

Got it. I sure hope this fixes it. I'm ready to actually drive this thing instead of spend time under the hood!

 

[Tireguy87]

Update: Pulled the coil to wire in the ballast resistor and the coil reads "no external resistor required"

Coil is getting 12v with ignition on and while running. I checked the resistance while I had it removed and its right at 9ohms. Cranked the motor and I can feel the coil heating up while the truck sits at idle.

Could my Mallory distributor require a coil with a ballast resistor?

 

[Pin_Head]

I would believe it when it says "no external resistor required".

It doesn't sound like an ignition problem to me anyway.

 

[miker]

I would believe it when it says "no external resistor required".

It doesn't sound like an ignition problem to me anyway.

x2

I still think the problem is fuel.

 

[Rockets2000]

I think you might want to rebuild that carb again, or better yet get a stock carb.

 

[Tireguy87]

Well I've got it wired up like the PO had it. New ballast resistor with his coil. Didn't get a chance to drive it but will in the next day or so. If that doesn't fix it, I'm probably going to a Trollhole carb and dizzy.

 

[Tireguy87]

Well guys I did some research on Holley carbs on other sites and found out that they are pretty easy to work on. So just for kicks and giggles, I pulled the fuel bowl off my "recently rebuilt" unit and found about a 1/8" of gummy fuel mixture settled in the bottom. I pulled both jets out and sprayed them with carb cleaner and also sprayed some on the needle valve and other areas I could access. Put it back together with a Holley non-stick gasket, fired it up, revved it up to 1500-2000 rpms and low and behold it didn't try to cut out. I'm not sure if the crud came from my fuel tank or was starting to build up while it was in the PO's rig, but I'm glad it ended up being something simple. I'll just have to keep a watch on it even though I have a glass fuel filter bowl and the fuel looks clean.

In this whole process, I also hooked up a ballast resistor and swapped coils. Looks like none of that was necessary but was a good learning experience non the less.

Thanks for the tips guys!