yeahford

Hey guys. I have a 98 f150 reg cab short box 4×4 4.6l 185k. This truck runs like crap and gets 7 mpg city. I changed the fuel filter (it was full of rust) and drove the truck. I was so excited (ran like new). Next day it ran terrible again. I changed the fuel tank, pump and filter again. Non of it helped. Then changed pressure regulator. Still no change.

Lean codes both banks.

It has not been on the road in a year. Really missing it. Considering buying some fuel line and fittings to replace main fuel line. Let me know what you guys think. Ive tried getting help with this before with no prevail.

Any replies appreciated. Thanks

Cmanjr

Did you check injectors?

ObsoleteE

Gotta agree with Cmanjr here, if your tank and filter were garbage, chances are your injectors need work too.

ibd2328

iTrader: (2)

Injectors are practically solenoids and easy to test.

Have you check for any manifold leaks.

trixR4kids

Keep in mind that a lean condition will come from not only from a lack of fuel, but an excess of air. If you have good pressure at the injectors, you may have air pulling from a vacuum leak or a bad gasket. You could always try spraying around your intake with some wd-40 or something to see if you can find a spot where things smooth out for you.

yeahford

I am not leaning towards and injector issue because the exact same running condition is present. If rust was to get to the injectors i would think that the running condition would be worse or at least different. Manifolds are leaking but were leaking during good running condition.

If what i said isnt right, let me know and il check injectors

4x4dave

^^ check for vac leaks. As others mentioned also check your injectors and clean them out. It also wouldn't hurt to change your plugs if they haven't been done in a while. They likely have an eroded electrode or blistered insulator if your truck is running lean.

If you still have problems after cleaning the injectors and changing the plugs chances are you have a bad vac leak or something along those lines. I would also check the COP's, but i don't think it would necessarily trigger a lean code. Posting a DTC would be a good start...

yeahford

The only change made to create a good running condition was fuel related.

yeahford

P1071, P1074...lean both banks. The fact that making a change to the fuel system made it run good is making me believe its fuel related. I have searched over and over for vac leaks, none present. Went through the lines and sprayed around everything with wd-40, starting fluid, and carb cleaner.

ObsoleteE

Sure, you can check to see that they work, but they may be partly clogged.