Sputtering engine when it's hot?

[emsxp]

I have a 1999 eddie bauer 4x4. My wife usues it 1-2 times a week as a rural mail carrier. It has been fine during the cooler months, however since the summer months have come I am starting to have a repeating problem. It seems that towards the end of her route, after a few hours of driving in the heat, the engine starts to sputter out. Her gauges are fine when this happens. The other day there was no porblem....and it drove fine while she worked. It wasnt quite as hot that day and she had an easier day. However this weekend was blazing hot and she had a normal to somewhat heavy load.....meaning a little more stop and go. Come the last hour of the route it started. She has to pull over and shut down, if it doesnt already die....wait 5-10 minutes and it starts up. I had a mechanic friend check it out....and he was wondering about the fuel pump or some sylinoids(sp)....ruled out the fuel pump and figured it may have been really bad gas/ water, b/c it started all of a sudden after she filled up at a certain gas station.....I then put some B-12 in the tank and filled up....on our 2nd tank of gas now....and its starting again.......I know for a fact if I walk out right now, it will run fine.......any ideas where to start looking for the problem?

 

[mawrazen]

Is there a CEL???

What codes?

You may need new O2 sensors. I had a similar problem and new O2 sensors cured the problem.

 

[emsxp]

I dont know what a "CEL" is / are....but I can find out....how $$ are O2 sensors....big deal or easy fix?

 

[emsxp]

By the way gauges and check engine lights are fine.....no indicators......another mechanic friend said that ford fuel pumps tend to shut down when they get hot......have 152,000 miles on the vehicle.

 

[ranger7ltr]

Has the fuel filter been changed yet?

This sounds like the fuel filter has become clogged up partially and when the engines' fuel needs are increased, the system can't deliver...

You stated the fuel pump has been ruled out and I am thinking that the pump shows pressure so the pump is deemed ok? Was the fuel pump pressure tested under the same conditions that caused the sputtering? If not, I suspect the pump pressure will show to be low or non-existant at that point...

The pump, however, will be influenced by the fuel filter mounted on the frame rail and this is the first spot to start and see what the fuel looks like on the inlet side...If this hasn't been changed, either look at the fuel that comes out of the filter or have whoever changes it and see what the fuel looks like...

If it looks like this, this is not from bad gas...Trust me I have been there...And the inside of my tank looks like this...

 

[emsxp]

well, I just bought a $360 fuel pump, motorcraft part#PFS-422.....everyone i telling me to go that route....and no, we have not tested the fuel pump pressure.....seems everyones experience is pointing to the pump......of course they are going off of what I explained. My buddy will put the pump on....and have him look at the filter as well. If he finds the problem, he will steer me straight.........what do you think about the pump?