Hi guys,

2000, F250, 4x4, Crew cab, 37" tires, no cat, 4.88 ratio, 5 star tunes, 200K miles

2 weeks ago the fuel pump got issues on my way back from a capig trip. lucky for me he truck limped to a town were i could find a replacement generic pump and fuel filter.

after a week the truck start stalling at idinlg after a 20 - 30 min drive. I was planing to replace the generic pump, just not that soon. Any way i got a new Bosch complete pump and swap it and put a new fuel filter

160 miles later the rpm's go crazy when idling. they start falling and the rising until the engine stalls. its the same behavior under 2000 rpm. as soon as the engine goes over 2000rpm it works fine.

any ideas? i'm thinking pressure regulator

Ivan E

 

Check your iac ( idle air control ). It could be the fuel pressure regulator as well.

 

Before throwing parts at it, clean your MAF sensor with MAF cleaner. Gray can made by CNC. And remove the throttle body and clean it good. Take out the IAC and spay it down good but don't push it in! Let dry, reinstall with new gasket, and see how it does. keep battery unhooked while you do this.

 

Never mind....forgot I was in V10 forum.

I would hook up a fuel pressure gauge and see what the pressure is when it acts up.

 

It really sounds like the IAC - before putting too much effort into swapping parts or anything else, when it acts up, try putting your foot on the gas just a little bit - like 1/4" and see if the idle smooths out and stays where it should. Once the IAC sticks, it seems the PCM goes nuts trying to control the idle and usually doesn't

 

Cleaned the IAC and now the problem is gonne. It wasn't that dirty though. But is located to discourage its regular cleaning. and the height of the truck was not helping

Now the truck whistles when i let go the throttle, and its getting louder. dou you think I messed the IAC gasket?

 

Or cracked the elbow on the front side of the throttle body. Whistle sounds like vacuum leak to me.