I have a 1992 F150 automatic 2WD with 5.8 liter engine. It performs poorly, especially upon acceleration. Once I get to cruising speed it runs well until I come to a hill or try to accelerate. At that time the engine begins to hesitate, and under heavier loads it begins to buck. Turning off O/D and bringing the rpms up helps the problem, but it returns when I turn the O/D back on.

I just scanned for codes and got:

181 Lean during part throttle
334 EGR closed, valve voltage high
542 Fuel pump secondary fault, PCM to ground

Timing is correct, O2 sensor and TPS are new, plugs wires etc are relatively new and in good condition.

What is a fuel pump secondary fault? Would that not cause the lean condition noted by code 181? Could the MAP sensor be part of the problem?

Any help is appreciated.

 

The 542 code is generally set off when you switch between front and rear tanks while the truck is running.
As long as both pumps are working, disregard that code.



-Chris

 

Thanks for the input. This truck has had the rear tank removed so I never switch between tanks. Any other ideas?

 

Well, if the truck had dual tanks and one was removed, of course the computer is going to see that there is no second fuel pump

-Chris