by dpuckett » Wed May 28, 2008 7:32 pm
Valves get a little light at 34-3500, and start to float with stock springs.
If you are having higher RPM problems, check a few things first:
Valve adjustment. If it's been 25K or more, it's time well spent. Even if they are in spec, it's worth knowing they are right.
Fuel supply to the pump, and lift pump pressure. I have NEVER had a good stock fuel system defuel at less than about 27-2800rpm. If your lift pump is getting tired, or is an AirTex, it could be failing to meet the spec of 5psi at idle and 3psi at WOT full load.
Throttle linkage and full travel of the throttle lever. Over time, the cheap plastic ball end caps wear and allow slack in the "system" so to speak. If your throttle rod moves more than about 1/4" before the pump throttle lever moves, bust the jambnuts loose and tighten that thing up.
Your injector pump could be in need of new springs and seals. Even though it runs, could it be better? Most likely if it is all original, yes.
Daniel
His- 93 W250 club cab LE, auto to Getrag conversion, piston lift pump, 3.54 LSD. 400k+
Hers- 04 QC 4x4. Built auto, Triple Dog, Air Dog. Funny Round truck that aint so quiet.