I have a 65 F250 with a 352. Installed RPM intake, Holley 4 barrel, MSD dizzy and plug wires, blaster 2 coil, electric fuel pump, 3g alternator, and a high torque starter. My issue is the truck starts great when cold, fires right up with 1 pump of the gas first. Once I have driven the truck, maybe 30 minutes so it is good and warmed up I can not get it to start again, or if it does start it does this bouncing idle thing where it keeps wanting to die and struggles if you give it gas. Sometimes to the point of killing it. If I time it just right with giving it gas I can get it to hold an idle, I am getting better at this each time. If I go somewhere and let it sit for an hour or so I usually only get the bouncing idle not the no spark issue.

This weekend it did that while I was at my brothers. We started trouble shooting again and found that It did not have any spark. Then suddenly after over an hour it had spark and fired up to the bouncing idle.

All of these parts were added within the last year and the truck has maybe gone 300 miles since then.

I am getting ready to go through the wiring again to see if I can track it down but want some input on what I should be looking for.

-Could be the ignition switch since the power goes through there before the coil.

-Bad coil? It is new but I know this can happen.

I love troubleshooting electrical issues but this one has me stumped.

Good thing I have a optima battery so I can crank on it for hours trying to get it to start again.

 

Ben, Most of these issues are the gas being boiled out of the carb and it not wanting to start, but once you get it going tis OK. You have a thermal break in the engine bay area that is shutting off the power if you are able to overcome it. I am going to say that it is at the front of the engine that gets cooled by the fan air and returns to operational. Could be coil or something in the dizzy. My Guess.



John

 

Run it until the condition rears it head then take a jumper wire from the battery + directly to the coil and see if it will get spark and run. If it does the problem is before the coil, if it doesn't the problem is probably the coil, they do go bad.
Does this coil require 12V? Do you have a wire bypassing the resistance wire?

I had a coil go bad returning from a camping trip years ago, we could make it about 10 miles and it would overheat and shut down so we would take it off and throw it in the ice chest, drive 10 more miles and do it again. That last 100 miles took forever

 

Thank you for the input guys. I will give your suggestions a try and see what I get. I know that sometimes new parts arrive bad, it could be the coil or the Dizzy. jumping directly from the battery is a great idea.

 

sounds like heat soak , boiling gas in carb add a pheonic spacer under carb

 

I could agree with that except that the op states there's no spark. Back to heat failure on the electrical system.

 

OP has not delivered yet, Going out to run her up to temp and do some diagnostic after I write this.

I do have a spacer under the Carb. I know it is getting fuel, can see it in the carb when you pump it and unhooked the fuel line and ran the electric fuel pump. I think it is a wiring issue when hot. I thought it might be flooding but when I pulled the plugs last time this happened the cylinders were dry. Even when I would pump the gas and crank it I never saw any fuel through the plug holes. I am new to working on engines so not sure if this means anything our not.

Out to the shop I go, I will report back later on what I think I have found.

 

I could not duplicate the no spark issue today. Warm or cold I have 12v at the coil when the key is in the on position and when the truck is running. I did not have a second person to check what the volts at the positive side of the coil was when cranking. It did do the bouncing idle thing on warm start once but only for 2 or 3 bounces. after that it started right up every time. I went through the under-hood wiring and everything looked good.

It is hard to trace the problem when I can't duplicate it. The thing I was wondering was if the electric fan that is on when the engine is at temp was sucking to much voltage. It is wired to not run when cranking to prevent this. I am getting 11.6v at the coil when the fan is running and the key is in the on position when the motor is running or not.

Should there be a resistor on the ignition wire when running a blaster 2 and MSD Dizzy? where was the factory resistor located? I do not know if I took it off or not. Don't see anything under the hood or the dash.

 

Isn't that always the way, won't do it when you want it too. I don't know what the requirements are for the blaster or MSD are, I don't run hot rod stuff on street trucks. There is no external resistor, there is a resister wire between the ign switch and the firewall connector, should be a pink wire, which only provides about 8 volts to the coil. If you are getting 12v it could have been replaced with a regular wire. That may or not be ok for that coil, you need to find the requirements for it.

 

Pink wire, interesting since it is still connected to it under the dash. Now I have to wonder how I am getting 12v at the coil when it is passing through that wire. The wire hooked to the coil is red with a white stripe and is the same on that was hooked up to the original coil when I purchased the truck a few years ago. Does that sound like the right color at the coil?

 

I've never experienced it myself but I have heard of people who would prematurely burn up points when the resistance wire went bad. Maybe someone will chime in on that. Red with a white stripe sounds correct but I don't have a wiring diagram handy.

 

"The thing I was wondering was if the electric fan that is on when the engine is at temp was sucking to much voltage."

what alternator you running , most electric fans require a higher out put alternator . most switch over to the 3g 130 amp alt when switching to elec fans

 

He already stated he has a 3G in the first post

 

I added a 3G after adding the fan and feeling like I was going to be short on Amps in the winter with the heater running. Easy upgrade to do and removes a bunch of wiring from under the hood.

 

I suspect here lies your issue.



John