i have a 99 f150 with 5.4. My problem is the truck will start, but then sputters like its being choked for gas stumbles and dies immediately. it was running perfect i parked it for about 4 - 5 hours and then came back. tried to start the truck it fires hits and starts, then stumbles immediately and dies. anyone know if it could have been fuel pump? or fuel filter? what does it sound like to you fellas?

 

Could be a dirty IAC, fuel filter, MAF sensor, fuel pump.. etc, a number of things. I would check to see if you hear the pump kicking on when you put the key to the on position. Then move the next cheapest thing and clean the IAC. See what that does.

 

ill try that. and see what happens. If it is the fuel pump instead of replacing the nat aspirated pump with a naturally aspirated pump, could i swap a lightning fuel pump instead i plan on a bit of mods later???

 

When you start your engine will it still run if you keep pressing on the gas pedal? That is what mine was doing before I replaced the IAC.

You can also try cleaning it,and it will work for a while longer. But, eventually I just had to buy a new one, because it kept acting up. Haven't had a problem since.

My truck is a 1999 F150 4.6 V8.

Good luck,
David

 

I haven't clean iac in a while, isn't it located in the intake tract

 

dbuck so far before my intake has been taken off and im currently cleaning iac, yes it will start but feels like an old carbd chevy small block thats out of time and i have to pedal it at rather high rpm's to stay alive, then when u let up it just dies like its being completely choked out or its way out of time get my drift.. i was thinking fuel pump, but if it was a fuel pump the engine wouldnt even hit would it

 

Take a hammer to the EGR valve. It may be stuck open.

 

may seem like a weird question but how hard should i whack it?

 

Hit it with the opposite end of your largest screw driver. Medium swing should do it.

That's the best I can do describing.

_____________________
Other possibilities:

1.Make sure your theft light isn't blinking upon start.
2.Check your inertia reset.
3.Swap relays. Your horn relay MIGHT be identical to the fuel relay. They were in 98, but the 99's changed somewhat.

 

well i woke up this mornin and got me a new IAC and dpfe or egr pressure contoller gonna try slappin those on today. if the theft light is still blinking whats up with that? plus are the horn and fuel relay underhood or in cab fuse panel? i checked the fuel reset or inertia switch on passenger kick panel, it wasnt popped up so it looks good to go.

 

You have to look at your owners manual in the glove box for relay location, their different in certain model years. If you don't have one, you can download it.

Have you tried resetting the KAM? Disconnecting the battery for adaptive strategy mode?

Theft light blinking can mean your injectors are shut down. A PATS problem.

Have you searched your problem lol .?

 

well i just installed new IAC which was a pita to remove because i couldnt get a socket on it had to use a wrench, felt like i was winding a damn watch on the bottom bolt. I installed a egr pressure controller/dpfe, and a new fuel filter. My theft light isnt blinking when its runnig and im pedaling it to stay alive. I reset the Kam, but put my truck back to stock settings with my edge before hand. i did try this however, when my mass air flow sensor is plugged in it will not idle, but if i unhook the harness from my MAF and start it it revs really high. could it be a Mass Air Flow sensor?

 

i have searched my problem and usually the IAC fixed it.

 

well i also checked relay/fuses they r good also and my theft light isnt blinking

 

hmm so noone has any suggestions, i gues im gonna take it down monday to a shade tree mechanic, id rather fix it myself but this replacing parts trying to find out whats wrong is an expensive journey, im tryin to save some money, cuz if ive got enough i get my exhaust installed finally!