I have a buddy who has a 2005 ford f250 with the 5.4. he wanted me to ask you guys since he knew i was a member here , and that you guys were a lot of help. His truck wont stay running. if you start it and drive for 10 minutes it will die. he says that you have to jump it to get it to start back , and it will fire right back up. run for 10 min and die again. he has replaced the battery and alternator and now hes at a loss. any help would be great thanks.

 

Well, the next step would be get a volt meter and determine if the alternator is charging the battery. Do not assume the alternator is good just because it is new.

Check his battery cables also. If there is any corrosion it needs to be cleaned.

 

ok all that is done and checked. still no go. any other ideas.

 

I would monitor the fuel pressure and see if it goes south just before the engine dies.

 

Sorry, odds are you wouldn't have the equipment to do that. Instead, kill the vehicle when its running fine, then take the pressure at the fuel rail.

Run it again until it dies by itself, then take the fuel pressure again.

If the second pressure is a lot less than the first, you have your problem identified.

 

even if it had no fuel pressure wouldnt it still crank, but not start? he says when it dies it wont do anything unless you jump it.

 

If he has to jump it, then the battery is not charging. As I said earlier, he needs to break out a voltmeter and figure out why the battery is not charging. If that was already done he would not need help.

 

Oh yeah, he definitely has electrical problems. But I'm guessing they developed because the car died on him and he kept cranking when his electrical system was marginal to start with.

I don't know if its true today, but it used to be that you didn't need a battery to run a car, inasmuch as the alternator/generator would produce all the juice needed to for the motor to run, indefinitely.

I'm a little hard pressed to believe that both the old and new alternators were bad to the point that the engine is dying after ten minutes. Hell ,a fully charged battery will run a vehicle for 90 minutes or so without an alternator.

So yes, he has electrical problems, but I suspect the underlying problem could be something like a clogged fuel filter......