Lift Pump?

[mschultz77]

Ok here is my situation. When I'm driving between 42-47mph and the rpms are about 1250 the engine revs up to about 1700 maybe a little bit more then back down to 1250. It happens either with or without a load and I dont think its the trans cause it doesn't feel like it shifting and speed remains constant. Also my mpg has not been what I thought I would get from a diesel. This is my first diesel, I got it about 2 months used and I love the truck, I'm just not sure about what to check or change. I've been reading alot of the posts here and the info has been great. I have guages ready to put in, but have not had the chance yet. Any suggestions of what to change or check would be great. Mike

[dodgediesel4x4]

Does this reving jump up by itself, while you are keeping the rpms (throttle) at a consistent speed? Like the engine is surging up? I'd put the gauges in ASAP just so you know where you stand fp wise.

[mschultz77]

Yes it does it by itself. At first I thought it was me moving my foot, but it has happened several times now.

Mike

[farmer dave]

It sounds like the tranny is slipping to me. When the tranny starts to slip the enigine doesn't have a load on it so it revs up in RPMs. I am just guessing, but it could be your torque converter. Just my opinion though.