F150 2004 trouble mailing rpm 3000-3800

[Pathfinder]

I have a 2004 f150. The motor is great except in the 3000-3800 rpm range.the motor will instantly own it's own drop from 3800 rpm to 3000 then go back to 3800 rpm without any touch of the throttle. I have been to the dealer and he's had 3-4 chances with no improvement. I have run the $50.00 a pint injector cleaner thru numerous times and no change. I convinced myself it was one one the switches on the gear shift and that was not the problem. I changed the bottom switch. Please let me know if you have had this issue.

[Pathfinder]

it will run wide open any time I want at 5400 rpm, so I don't think it the fuel. its is like the engine is getting incorrect inputs from somewhere .

[TownsendsFJR1300]

it will run wide open any time I want at 5400 rpm, so I don't think it the fuel. its is like the engine is getting incorrect inputs from somewhere .

5400 rpms is very different than when its happening. There may be just enough pull for the fuel at WOT, at mid throttle, not so.

When was the last time you checked the under cowl fuel filter? Have you drained the VST filter, (phillips head screw with clear plastic hose next to it) into a clean can and see if CLEAN, clear, non-varnished fuel comes out. Very simple, might take 5 minutes...

IMO, I would start with the basics, the secondary tank being the first thing to check.


Did the dealer hook it up to a lap top and check the electrical inputs, setting, etc? That should be able to find most anything electrical out of line of normal. Most minor fuel issues WON'T pop a code, ie air leak, bad O-Ring at the under cowl fuel filter(air leak), etc BUT will cause running issues.. A transom mounted fuel filter with a leak/clog won't show on the YDS either..


With the dealer unable to help, there's MANY years of experiance here, you might fare well to listen to it as your running out of options..

Good luck..

[TownsendsFJR1300]

Also, was anything recently done ot the boat?

Was it used regularly, non-ethonol fuel with fuel stabilizer?

Fuel will go bad in as quickly as a month. About the best fuel system cleaner, IMO, (and NOT cheap) is "Yamaha's "RingFree". It is NOT a stabilizer, BUT works EXTREMLY WELL.

[Pathfinder]

Thanks for the tip. We have done about everything except the fuel line issue. I know the bulb is not fully inflated so that now may explain why.