truck starts and runs rough. Has absolutely no power - Diesel Forum -
6.9L IDI Diesels (Not Power Strokes) Technical discussion of topics related to vehicles powered by the 6.9 Liter In-Direct Injection Navistar engines.

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post #1 of 2 (permalink) Old 08-01-2019, 11:42 AM Thread Starter
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Post truck starts and runs rough. Has absolutely no power

I have a 1986 F250 with the 6.9 IDI. It will start and run very roughly but has absolutely no power or acceleration. I have installed new air filter and fuel filter. It seems to be getting gas from the shrader valve as it should. Don't know where to go from here. Any suggestions would be greatly appreciated.
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post #2 of 2 (permalink) Old 09-11-2019, 08:00 PM
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If you're pulling fuel @ about 1/4 of a tank your Cone of Failure may have failed and you're sucking a lot of air. If so, add more fuel to the tank and see if there's an improvement.

If not and you're sure your getting fuel like you should be then you may have a failing injection pump or fuel injectors.

The beauty of the simplicity of the IDI is that if it starts and runs then what little electrical there is is working, the motor's probably good, so that leaves the fuel system. It then _has_ to be a fuel problem. Drained your water separator lately?
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