This is on my 97 F150 xlt 4x4 w/4.6V8 automatic. Truck has 115k miles.

So sunday I was driving on the high way going about 50-65 mph. All of a sutton the rpms dropped like the car was going to shut off. Check engine light flickered for a second and the car cought itself.
It did it like 2 times and then didn't do it again. Drove fine the rest of the day.

Next morning drove it to work. No issues drove like it always has. On the way home though it did it 3 times in a row and then finally just shut the truck off. I had to coast into the EM lane. Tried to start it but no such luck. Just cranks but doesnt start and run. Had to have it towed home.
Got home and the tow driver got in the truck put the key in and it strated up. He was like hmmmm, and me too.

So am I looking at the fuel pump going bad or is bad already?
Fuel injectors?
Or something else?

The truck started up fine all days, idled fine too. Does now too.

No check engine light is on now, and everytime it acted up the light would come on for a split second then
go right back off.

Spark plugs are all new and motorcraft. Only one needs to be replaced on the passenger side back. It's a
pitta to get to. Dont think a bad plug would cause my issues though. Also has a new fuel filter.

Anything else that would cause my symptoms?
I was thinking maybe fuel pressure regulator, but the truck should still run, just not good correct.
If that was it, it would run rouph all the time not just all of sutton.

Thoughts/suggestion.

Whats the easiest way to change the pump. ( have a full tank of gas right now 24g)

Thanks,

 

So you don't want to test anything ? Just throw parts at it ? - We suppose to guess which parts to throw at it?

You have something against diagnostics lol.

Well, I don't so here's what yuh do, -

You might have a DTC in memory, check that first/ then pressure + regulator.

So how old is the filter exactly? - And change that plug, geeeze..

 

nothing against testing!!!
checkign the DTC is going to be hard since I have no scanner and the truck is parked at home right now.

I was only guessing the fuel pump since it's not a consistant thing and has gotten worse over the few days. Plus after it sat for about an hour it worked again.

The fuel filter has maybe 1k miles on it. Got it changed over the winter.

I plan to change that plug. I just dont think it would cause the truck to die while driving at a constant speed and then not let it start back up but will later on.

What pressure should I be looking for with the truck in part and running? Or how should I go about checking the pressure? Like I said it idles fine.

Testing the fuel pressure regulator, how to test it, and what to look for?

Thanks!

 

haynes manual says...... fuel PSI at idle vac. hose attached 30-45 PSI vac. hose detached 40-50PSI.

haynes also says. use a stethoscope or screwdriver and put it on the injector and it should make a steady clicking sound that rises n falls with engine RPM.

you could also crack the fuel line before the fuel filter turn the key foward and see what ya got but the fuel pressure test would prob be better.

im not sure how to do it but i know with a voltometer you can check the ohms on the injectors. maybe jbrew knows how to do it.

also do a fuel amount test or somthing i forget what its called its were you open the purge on the gauge and pour it into the a bottle it should fill a 1/4 of a 2 liter in about 5 seconds or somthing not to long *Hey look college is paying off for me!!!*

 

Can you drive it to a parts store? Most of them do free scans.

Otherwise, this is a cheap usable scanner:

http://www.amazon.com/gp/product/B001LHVOVK