Hi new to the thread i have 2 issues with my f150 its a 2001 xlt has the 5.4 Triton in it the truck starts but when i step on the gas it sputters and cuts off i replaced the coils plugs pcv valve still sputters and cuts off im thinking fuel pump but i noticed the lights dimming when it was sputtering one day i haven't seen it again since then but that made me second guess the problem being the fuel pump also my tail lights will not work brake lights work turn signals work i checked all the fuses i couldn't find a relay for the lights if there is one i couldn't find info on one also didn't notice any shorts any ideas on either issue

 

Have the battery/alternator system checked.

 

All the lights work except the running lights turn signals and emergency lights work fine headlights work fine

 

thanks I already replaced the battery I was going to do the alternator

 

I had similar issues and symptoms when my fuel pump got weak in my '99 w/4.6L. Check the running fuel pressure on the fuel rail. Harbor freight has cheap fuel pressure testers that work.

 

any idea what the fuel pressure should be I know my uncle replaced the fuel pump but with a pump from the junk yard

 

I think yours is supposed to be about 35 psi.give or take 5 psi.

 

Thanks appreciate it I'll have to check this weekend