1500 rpm noise and all around roughness

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I have recently noticed an all around rough feeling of the engine. I can "float" it around 1500 and really hear it, but it also has a slight rough idle and rough feeling all the way through the power band. above 2500 seems smooth, but hard to tell. Have changed oil and filter, fuel filter and air filter within the last 3k miles. Tried LSD and ULSD, power service white bottle, and tried NAPA anti-gell and fuel conditioner as well. Seemed a little better on LSD, but don't know if it was all in my head or not. 129,500 miles on it now. Don't think it is trans or driveline related as I can feel it in the pedal so to say.

 

Any thoughts? Could it be the lift pump going?

 

Does the vibration occur when the truck is not moving?

 

yes. I am sure it is in the engine. Driving, neutral, and parked it is all the same. A little worse when under a load though.

thanks

 

Have you pulled the inspection cover to verify that the flexplate bolts are tight? Can you listen to the noise with the hood up, from on top and underneath the truck to discover where the noise seems to be emanating from?

 

sounds like a lifter type noise to me..... thought maybe it was an engine noise due to low fuel psi???

 

What's your lift pump fuel pressure?

Any loss of power while driving?

 

still trying to get adapter to hook up for fuel psi. have gas psi guage, but won't hook up to this truck.