I have a 1991 F-800 with a 429 that is giving me some problems. It is shutting down after it gets warm. I was hauling a load of rock and it cut off on me three times. It would be running great and just act like you cut off the switch. I could pull off the road, put my brake on, cut off the switch, and let it set for 30 seconds, and it start right back up and would run fine for about ten minuets. It did not do it on me at all till I was 20 miles from home on a 60 mile trip. I am figuring it is something electrical, but anyone have any idea what it is?
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Possibly the ignition module. Should be mounted on the fender on the driver side. Trace wires from the distributor to find it. The "TFI" system has a history of failures similar to yours, as well as total failures--usually while you are crossing a RR track or in the left lane of a freeway....

 

Yeah, I bet it's the ignition module too...

When it does this, and won't start, I've put a bag of ice directly on the ignition module to cool it off, and see if it starts. Of course, a bag of ice is hard to come by on the side of the road. A "cold pack" from a first-aid kit would probably work too...

 

Any Check engine light? Got an OBD1 scanner?

 

In my 89' F-700 with the 429 I had a similar problem. It would die randomly and then after some time start up again. It eventually quite starting up. I replaced the ignition switch that is lower on the column that the rod runs to. It started up fine after that and ran good until it got a crack in the block.

 

It was the module, I have hauled a couple of loads of rock and it has done just fine. Thanks

 

Thanks for reporting back

rep points sent.

 

Does your truck have the tilt hood were is the module located?

 

Yes, it has a tilt hood, and the module is on the passenger side at the bottom of the raidator support, on the outside of the suppport.

 

Thanks for the info mine is a 1998 and they changed location of the module its behind a plate on the fire wall on this one.

 

Is your 429 FI? Mine has a 4bbl carb on it and I get 5-6 mpg. I was wondering if a FI got any better.

 

Mine is a 429 with fi maybe one mile a gallon better.