1979 Ford F100 update

Britcheflee

Well-known Member
I have been having problems with my old ford truck starting - it starts great when cold - runs great and if I stop and re-start it starts instantly BUT if I wait about 15 - 20 mins it will turn over and not fire - if I wait another few hours it will start fine again.
I replaced the ignition module with no difference - yesterday I swapped out the coil (I think the one in there was the original) plus the horseshoe connector which seemed to have worn/dirty/loose connectors - this time after the 15-20 min wait it started but not without a struggle - had to keep turning it over until it finally caught - would nearly fire, fire a couple of times and die and then eventually fire up and run - once started it then will start right up once run for a minute or so.
This is an improvement over the no start at all but still not great - is there anything else I can try to see what the problem is? I am almost thinking it is a fuel issue? Water in the carb..but why would it start perfectly right after it has been running and switeched off like that? This has the duraspark ignition system with the pick up in the coil and an ignition module - previously has been super reliable when starting.

Thank you

Lee
 
I have 2 of that vintage. One has a 390 and one has a 460. I find that the replacement modules can be suspect. It could also be a float that dropped or a bad needle and seat that is flooding the engine after the it is shut off. There is fuel pressure feeding into the motor and flooding it if you leave it off long enough. When it is off a long time, this fuel evaporates and so it doesn"t flood.I bet you have to have your foot on the floor to start it when it is acting up. Check the carb and replace the needle and seat.
 
short of a carb rebuilding, after sitting for a spell, might have the tea kettle affect, where the fuel boils into the engine, causing to flooding, because of new gasses, could maybe clamping neadle and seat stuck, from the rubber tip geting hot, then expanding while sitting, put a fuel pump tester on it to be sure pump isn't going out, then maybe think about carb.
 
Does it still have the thick spacer between the carb and the
intake? If it does, does it have the 1/4" gasket between the
carb and spacer?
 
I haven't ever had those modules act like that. They have always caused it to die when running and then wouldn't restart. After 15 minutes it would start normally.

I go with fuel. I know it is winter, but is it warm enough anywhere around the engine to cause vapor lock? They say this newer fuel does it easier. Does it have a mechanical pump? Wondering if the pump bleeds off after that long and has trouble pulling fuel when the pump body is hot. I think fuel is the direction to go.
 
Check it for spark when it doesn't start. Clamp a good plug to a solid ground and see if you have blue spark that jumps a 1/4 inch gap when it won't run.
 
(quoted from post at 11:42:15 02/18/13) Does it still have the thick spacer between the carb and the
intake? If it does, does it have the 1/4" gasket between the
carb and spacer?


Sorry, I need a clarification on this - are you talking about the intake manifold?

Lee
 


would a rebuild kit for this carb be sufficient to stop it from flooding? If the power valve is blown on this carb is that repairable? I do indeed have an inline filter - will check that as well.
Thanks,

Lee
 
May be, but my experience with those leaking Holley power valves is that when leaking, they NEVER run good at ANY speed, ANY temperature, etc., etc.
I'd bee looking at float, needle, seat.
 

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