I have a 99 F150 4.6. Sometimes is sputters a bit when I start it but then idles fine. I have no power when pressing the gas pedal more that about a quarter of the way down. It's hard to maintain interstate speed on any incline. I took it to the ford dealer and they said my fuel pressure is too low and want $1300 to put a new fuel pump and clean the injectors. I got two codes. One was the oxygen sensor the other was the catalytic converter. I changed the sensors and it didn't help. Any ideas what may be causing this?

 

A plugged cat will do that. Take it to a muffler shop to get that diagnosed.

You need to post the exact codes to get good help.

Low fuel pressure can also be as simple as a plugged fuel filter or bad pressure regulator.

 

2 things to consider 1 a bad fuel regulator or a worn fuel pump. Simple maintenance like replacing the filter could solve the problem.

 

LOL $1300 bucks! filter. If that dosent solve it you probably need a pump. You can get an OEM pump for less then $300 I'm sure @ rockauto.com Do it yourself and make a grand!

 

I will have to get the codes. I replaced the fuel filter. I have not checked the fuel regulator. One of the codes did mention a bad catalytic converter. I took it to ford because I wasn't sure how to check it. I'm not sure based on the codes why they even checked the fuel pressure before checking the cat. I think I will have that checked next. I was told if I can get to see the exhaust manifold that I should loosen it to see if that relieves the back pressure. Does that sound like a good way to check it?

 

No, take it to a muffler shop to get the cats checked.

 

So I went to the muffler shop and 4 new cats and $600 later same problem. They think it's the fuel pump because of some lean fuel codes. I guess fuel pump is next unless there is something cheaper and easier I can try first

 

Again, please post the exact codes!

 

Unfortunately there is no good "scatter gun" for people who like to get codes from and listen to advice from parts salesmen and then buy parts and THROW them at their truck trying to fix an unknown problem. (ie: Code P0430 does NOT automatically mean a bad catalytic converter and P0174 does not automatically mean a bad Injector). Best that can be suggested in this situation is to find a 10ft section of 8" or 10" water well pipe, cap it at one end and drill a 1/4" hole about 1 foot from the cap, then pour about a pound of gun power down the open end and stuff your random selection of parts in the open end. Place the butt against a fairly sturdy point about 40 yards from your truck, like maybe a concrete bridge abutment or overpass pillar, and aim the open end generally at your truck and strike a match near the hole that you drilled. Then you start it up and report back here whether it helped or not.


TRANSLATION - @glc is correct. To get useful help here, POST SOME CODES like he suggested and do some further tests based upon those codes. Also, @glc said "go to a muffler shop and get the CATs 'checked', not to replace them.


Members here really want to help - but you've got to help too.