Have a 99' 1500 Club Cab 2x4 V8 318. No problems until suddenly...was driving to work and began losing power. Tried to excelerate & truck began "spark-knocking". Speed decreased immediately, then could not exceed 15mph.. Engine acted fuel starved. Motor idled fine until I disconnected battery to try to reset computer. Now, motor did not want to stay running, idles very hard, hard to start. Ran OBD-said "no codes". Fuel injection pressure test ran between 40-45 psi. Replaced fuel pump. No change in problems. Love my truck, but... I'm really stumped!

 

Im not a gasser expert but one easy thing to change is a fuel filter. The higher the engine revs, the faster fuel must flow. More flow means more particles get pushed to the filter. They build up and constrict the amount of fuel available to the injectors. When the truck sets for a bit, all the particles settle and you have what seems like "adequate" pressure again.

A clogged line makes it easy for high pressures to be achieved. You may not be flowing the volume that's needed.


And the only other thing I can think of, and I am not sure you have one, is a pressure relief valve in the return line portion of the system. If it sticks open, the system has a hard time maintaining enough fuel to the injectors.

You're cat is not clogged at all?

Just a guess, I'm mostly a diesl guy.

Good luck with your ride.

 

I had a car (Crown Vic) do the same number with a bad MAF sensor. Unrelated rig, but worth checking.

 

Sounds like yourcatalytic converter. Could be your coil too.

 

Have to second the bad cat. Remove your front O2 sensor and see if the truck improves a little bit.

DD ... the fuel filtration system on the gassers is actually part of the fuel pump. They get changed at the same time.