problems with hot start

todd jo · #1 (**permalink**) 07-04-2009, 12:51 AM

My new to me 78 f250 4x4 has a hot start problem. The first thing I noticed is this: (after 45 min. drive at 70 degrees ambient temp) the 429/auto would die when I stopped. Then it was terrible hard to start. Lots of cranking and pumping the throttle. I changed out the duraspark ign. module and the die-ing problem has so far went away?! Now after it runs and I go to start it back up it takes 5-10 seconds of continuous cranking and some foot feed to start and then it seems fine until I start it hot again.

I have ruled out the carb for these reasons. Stone cold I verified the electric choke was working. With one pump to the floor and one rotation of the crankshaft she springs to life!

Could it be the coil breaking down when hot? It seems like if the coil was bad it would just die on the road while driving?

How does spark advance effect the hot start? Have not checked the timing and dont know what it should be. I dont even own a timing light. I usually run all my points ign. on the ragged edge of detonation. I use a tach/dwell meter to dial the points in. I have zero experience with the duraspark. I do not know if dwell is a factor or adjustable on a duraspark system.

Your thoughts, comments, suggestions please

Todd

Bullitt390 · #2 (**permalink**) 07-04-2009, 01:02 AM

Check your float height, it could be too high or too low and once the engine warms up the fuel can start boiling causing the stalling.

Although 70 degrees is hardly anything though.

Josh

todd jo · #3 (**permalink**) 07-04-2009, 01:11 AM

The stalling issue seems to have disappeared after the new ignition module.

Bullitt390 · #4 (**permalink**) 07-04-2009, 01:21 AM

The symptons you described do not point to the module.

If you want to spend money on a bunch of crap you don't need, go ahead. But don't bite the hand of FREE advice.

Josh

todd jo · #5 (**permalink**) 07-04-2009, 01:34 AM

All kidding aside I am not hungry! I thought perhaps you misread my post. I was hoping not to have to dive into the carter AFB. I am a holley man, and dont know the first thing about checking the fuel level in the float bowls. After thinking about what you said, it could be that: the fuel level is low and when I try to hot start there is no fuel there cause it has evaporated away. Can you tell me a procedure to check this possibility? Do have any idea what the fuel level should be in the fuel bowls?

Todd

montana_highboy · #6 (**permalink**) 07-04-2009, 06:15 AM

Timing that's too far advanced will cause a hard to start condition when engine's hot, you may also be boiling off the fuel in the float bowl after shut down requiring the excessive pumpimg/cranking on start-up, a phelonic carb spacer will eliminate this issue.

Bullitt390 · #7 (**permalink**) 07-04-2009, 10:51 AM

Easy to set the floats on an AFB:

Remove the top cover, and turn over to set the wet level which should be 7/16 against the gasket... and turn over to set dry float which should be between 15/16 to 1"

Josh

todd jo · #8 (**permalink**) 07-04-2009, 12:16 PM

I will take it for a spin and dig into it. Let you guys know what happens after the holiday weekend.