Periodic bogging down

[greasemanicure]

Among its other oddities, our 96Ex4.0OHV has been having short burst of loss of power. Not long lasting but sort of like letting up on the accelerator for a second or so and then going back to where it was. The brief drop on the tach looks like maybe 250 to 500 rpm. Does not seem like ignition issues for some unexplainable reason. Starts right up every time, hot or cold. First bout of loss of power does not happen immediately but maybe after ten minutes or so. There does not seem to be a pattern or rhythm to it. Fuel pressure is solid under no load at any rpm.

Without drilling a hole in the hood, how can one watch the fuel pressure under load? Fuel filter is not that old. How about the in-tank filter? I tried driving with the gas cap loose to see if it may have been sucking a vacuum on the gas tank. If it is not starving for fuel, could something be randomly impeding the air flow?

The only code is a P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1).

Have you seen this?

Joe

 

[Lube]

This wasn't on an Explorer, but I've seen the rubber components on an in-tank fuel pump start disintegrating, and in the process interfere with fuel delivery on a random basis. Like any other rubber, it dies with age.

 

[greasemanicure]

Thanks! Lube

Makes sense. In particular if there is any rubber in front of the pump. It would collapse as the pump drew a vacuum, and then release.

The only thing I noticed today is that on the way to work, a 15 mile trip, it bogged down off and on most of the way. The temps were in the upper 70s. On the way home I did not catch it bogging down with the temps over 100. Not sure if that has anything to do with it.

I guess I'll run the tank near empty and take it down.

Joe