Help please, I have a 2003 f150 lariat 5.4 4x4 with 138 thousand miles always gently drive if ever drove.
It was sitting for maybe a year but my sis first day driving it the fuel pump went out, so she had a new fuel pump put in but didn’t do anything else like hoses or anything else referring to gas (by a 19yr old that grew up working in vehicles with his dad he also changed the spark plugs) she had mentioned after that it hesitates when accelerating she stopped driving it.
I came home started driving it that happens either going up a hill or just accelerating (even if I push down before a good distance b4 going up a hill it will do it) I changed the fuel filter/got a new air filter cleaned the air flow thing the is connected to the air filter and the throttle thing (that opens when u give it gas) it ran great for a week or 2 then started again.
I put the code reader on it and it has a p0174 code and a 02 sensor on bank 2 that’s all that had came up! I am thinking I need to redue the spark plugs and coil packs (coils never been done) honestly nothing really has been changed it’s all the same from when my dad bought it new! So with that being said I think I need to change spark plugs and coils and the big question is DO YALL THINK IT IS A WEAK FUEL PUMP?? or is the fuel filter clogged again???
I have a big feeling it is something with the fuel line ! Also now sometimes like 2 times when I have the ac on and it’s about to not accelerate the ac slows down and switch’s to the floor then it will go back to regular ac ! Please help me I mean I know it can be numerous things but I have a strong feeling it’s a weak fuel pump or spark plugs and coils !! When I got it I ran gas down filled it up put that Lucas fuel injection cleaner in it and used 89 gas instead of regular ! So what do yall think?? Or do I take it to ford ! ???

 

Please refrain from posting multiple threads regarding the same topic

 

That was quite difficult to read. I think the jist of it is.

The truck has 138k miles and has original plugs and coils. The truck has low power on acceleration and is throwing a code. The fuel pump has been replaced.

1. it is very probable that a vehicle this old, with that many miles, needs new plugs. Bad plugs can cause a misfire and stuttering. They can also cause a code if fuel is not being burned. That would be my first thing to do.
2. I don't completely understand why the fuel pump was replaced but feel that was probably unneccessary.
3. I would stay out of the fuel lines, filters, injectors, or any other part of the fuel delivery system until I changed the plugs.

 

i think vacuum leak, P0174 (Lean code) and HVAC system that sounds like it is defaulting to defrost due to lack of vacuum

 

Is the fuel filter positioned correctly? What's the trucks fuel pressure numbers? Don't dump any more snake oil in it.

This is important so give it some thought - Under normal acceleration from idle where exactly does it begin to hesitate or misfire At which speed ?

 

SERIOUSLY THANK YALL FOR REPLYS
the fuel pump was changed because my sister said the day after she started driving it the fuel pump went out she had someone change that ( he only changed the pump nothing else (19yrold kid))
also I had changed the fuel filter well my buddy did (motorcraft filter) the issue stopped for maybe 2 weeks then started again! Some one said filter might be dirty again! Unit is facing the right way but I cannot speak about the fuel pump or anything else
it does Not throw a code for anything else besides a lean code
I ordered spark plugs and coil packs from Amazon 8plugs 8coils motorcraft as well they should get here today
i was going to change them and see if that still Happens before I do anything else
SO THIS HAPPENS at 1500 through 2000 rpm 40 thru 50 mph more or less It does not have a rough idle or nothing else out of ordinary and it does not have high rpm’s

 

And I have not checked the fuel numbers but all honestly I know it’s something with the fuel I honestly think it’s a weak fuel pump but how would I check those numbers out??
AUTO ZONE ?? I wouldn’t know what to do honestly

 

There is a schrader valve on the passenger side fuel rail that you can connect a fuel pressure tester to, pressure should be probably in the mid 30's running or around that neighborhood.

 

I can do that at auto zone?? Or do I need to find someone with a gas gauge ??
And if it’s in the 30 range then the pump is normal right ???

 

Remove the throttle body MANIFOLD and CLEAN out all the old crusty carbon buildup. Bet that helps.