A buddy of mine just came back from a trip. He had the truck serviced somewhere, including the fuel filter, and the guy poured (presumably fuel) into the housing out of an old can.

Since then, he's had a drop in MPG and a knock at low RPM. This is the 2003 I bought new, and he bought from me.

Anyway, I went over to listen. Sounds perfectly normal at idle, but when you throttle it up you can feel a miss.

Once underway, you could hear what sounds to me like one injector knocking, but only when lugging down around 1000-1200 RPM. You could also feel a vibration like a slight miss.

We dumped out the Filter housing, poured in some seafoam, and put 1/2 a bottle of stanadyne in the tank, and ran it hard up a steep grade (camper attached) a few times.

It seemed to reduce the knock quite a bit, but you can still hear it under some circumstances...


Suggestions? Is there a way to determine which injector is the problem other than the dealer computer?

 

"Is there a way to determine which injector is the problem other than the dealer computer?" Not that I know of, but using a DRB to test injectors and fuel pressure is about the fastest and cheapest in my opinion. Usually one hour charge to do the scan. Good Luck.

 

Yeah, that's what I figured.

It clearly improved running cleaner through from the filter canister.

I'm kind of tempted to see what dumping a full bottle through would do...