While comming home from our X-mas tree harvesting activity last sunday. I noticed a very slight but noticable pause in the truck while cruising down the freeway. Hard to explain, but every so often I can hear a what sounds like something engaging (similar to the Jake brake but not as sevier), with a slight vibration and I can feel it drag/slow the truck down ever so slightly. At first I thought maybe it was the alternater cycling, so I closely watched the volt meter and it didn't even flicker when this happened. Then I thought maybe a fuel issue, but my fuel pressure guage stayed steady at 9.5 without so much as a flicker either.
My thought now is that maybe my vacume pump bearings are getting ready to fail. But the brake still works as it always has?

Any thoughts?

 

Those vacuum pumps have been known to fail, but usually they describe it just stops pumping...

Do you have your stock belt?

 

My vacuum pump started squeeling intermittantly about a week before it failed. Also, there was evidence of black grease leaking out.

--Eric

 

Well, it seams I ruled out a fuel issue a little too prematurely. It kept getting progressivly more noticable so I just for $hits and giggles changed out the fuel filter.

Imeadiatly, all symptoms were gone!