I don't have a clue why my diesel engine runs great for 6-8 minutes, and then revs up for 40 seconds, then smooths out to normal rpm's. Unfortunately, my tach does not work, but it's hard not to hear it whining. My guess is it has something to do with the fuel, water or dirt, or any one of the three filters is flowed. I am replacing all 3, just in case.
Anyone have any thoughts?