I drive my 98 cummins 24 valve after engine is cooled, and within the first couple minutes the rpm's go down to zero (as if the gauge has stopped working), which results in a bit of a power loss (kinda laggy). then after a couple more minutes the rpm's shoot up to where they should be and I get full power back. Now this only happens after a cool engine and once i get the full power back, the rpm's will not drop again until the next driving time and the truckhas beenshutoff and engine has coooled. any answers orsuggestions???

 

change fuel filter first.

then if it continues, it may be a faulty pump or computer .

sounds like lack of fuel pressure after it sits.

 

after the fuel filter change, get your lift pump pressure tested to make sure it is still working properly. . .if the lift pump dies your injector pump will also die if your not quick to recognize the problem.

 

Ihave changed the fuel filter 3 times in the last 6 months thinking the same thing, soI will go the other routes now. Thanks

 

My 98 24 valve 1 ton used to do the same thing. I would watch the voltmeter and it would drop to arounds 8 amps or so. I would have a power loss. I always figured that I wasnt getting enough juice to lift pump so thats what caused it. It would do it real bad on cold mournings.