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Old 25-01-06, 06:56
Lang Lang is offline
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Join Date: Jan 2004
Location: Brisbane Australia
Posts: 1,650
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While Keith's comment that "these were designed to operate in these conditions" might be a reasonable assumption, I do not believe it is so.

CMP's of both types and Dodges were designed and tested in areas far removed from 100+ degree temperatures. The stories of Fords, in particular, but Chevs and Dodges also, boiling and vapour locking in hot climates come from almost every driver who sat behind the wheel in the Middle East, Pacific Islands and Northern Australia.

Without the simple, cheap and obvious solution of putting an electric pump on the truck you are left with getting everything in the fuel system running perfectly as Keith suggests.

The first thing to look at is the fuel line and filters. If the pump has got so hot that it is "wheel spinning" on fuel starting to vapourise it is not going to lift as well. Check all lines are fully free and filter perfectly clean. Filter might be OK but blow back into tank to see pick-up is clear. Tighten and check all lines and unions for leaks - these may not show as fuel weeping but may let air in when pump sucking starts.

Are all fuel lines well away from the engine, particularly exhaust manifolds and pipes? Are any heat shields in place and properly positioned? Some vehicles have a tin plate fixed to the fuel pump bent to catch air from the fan and blow it over the pump.

I assume your main problem comes after stopping for a short while and heat soak from the engine heating the fuel pump or if you are grinding up steep hills on hot days. Have you taken the thermostat out of the engine - if so put back a new one! Does the engine run at 180 degrees in normal service? If it runs at 190-200 on a slightly warm day or with only a moderate amount of load or hills you should look at that - clean water system and check the thermostat. Maybe those rotten Ford water pumps are faulty.

You might try using AVGAS 100LL from your local airfield. With the price of normal fuel today, it wont be much dearer than service station fuel. Much better for the engine also for, despite its Low Lead name, it has heaps more lead than modern car fuel and is great for old valves. Main point is its vapour pressure (the point where it goes from liquid to gas) is much higher than car fuel and might solve you problem without doing anything else.

Lang
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