On my '92 f150 5.0 it has a crossover tube that connects to the back of the heads with a check valve in the center. Upon further investigation this valve has rusted through and was just hanging on by the hose that attaches to it. What would this cause? The reason I ask is that the truck acted up lately and would randomly start start acting like it was not getting enough fuel or just running on a few cylinders...no power at all in drive (pedal all the way down, and barely moving forward). I checked fuel pressure and it was around 34psi...I had recently changed the fuel pump.

I'm hoping this valve may be the solution?

Thanks,
Matt

 

That is part of the air injection system that feeds air to the cats to help them burn off excess hydrocarbons at cold start. But the system should not let any fresh air in once the engine warms up to operating temp and the computer goes closed loop as that will produce an excessive lean condition and loss of power, so you either need to replace those parts of remove it all and plug the holes in the back of the heads.

 

Thanks, I got a new valve and will get it installed. Do you think this would have caused the symptoms mentioned or should I also be looking elsewhere?

 

Yes your symptoms match a lean mixture problem that could be caused by that broken valve.