Ignition problems

[Masakis88]

Okay in Washington it's about 35 degrees and once my truck is cold no problems starting my 67 f100 390.

I go and drive around town no problems at all but once it warms up and I park it and go back 5 mins it won't start.

Sounds like battery won't turn over and u can here a clicking sound and if u hold it down sounds like a mini machine gun click. If I go back the next day it starts fine.

Seeing why once I drive and it warms up it won't start again for a while. Just started doing this the other day

[Lee]

Hi,

Since the truck cranks well when cold and is a hot start only problem it sounds like heat soak.

Are you running Headers?

A common problem with headers is they "heat soak" the Stater motor. Once it is heated up that hot, it looses it output torque and can't spin the engine over.

I had this problem too. I bought some of the foil insulation blanket material made just for this. Pain to put on but after 10 years it's still on and no more problems.

If you are not running headers and are still running stock exhaust manifolds, then my next best guess would be that the ignition timing maybe retarded to far.

Also, maybe the battery is to blame. Take it to one of the chain auto part stores and they can load test it.

Hope this helps, be sure and report back what you find.
Lee

[1972hiboy]

Time to get the multimeter out, when this problem is happening, check voltage at battery then work your way down the cable connections until you get to the starter.

[fordman]

Probably heat soak of the starter. Mine did the same thing.

[ThinLizzy13]

X3 on heat soak. I had a 352 that did exactly what you're describing. Put that foil around the starter and it never gave me a problem again.

[Busboy]

I say NOT heat soak. The "mini machine gun" sound is the clue that the starter relay is not getting enough voltage. Have the battery load tested at a shop that has a carbon pile load tester. If it's a 500 cold cranking amp battery, they should load it at half cca: 250 for 15 seconds and the voltage at this load, after 15 seconds should be 12.6 or higher. No other test is valid.
Assuming that passes, it's time to look at the battery cables and connections. Absolutely no green or white corrosion is permissible. And if you have those bolt and strap type battery terminals please throw them away and start over with decent, good size cables. This applies to both positive cables and of course the ground cable.