why does my F115TJR 2005 jet crap out

[bforsythe1]

If I ease the throttle forward it runs great to about 4100, but if I push the throttle all the way open about i/2 the time the motor starts crapping out-accelerating and deaccelerating. The injectors were all tested and all flow over 100ml. They all test great. The injection fuel pressure is good. No water in the gas. Have not pulled the vapor separator to check that filter. where do I look next. It feels like a fuel problem.

[TownsendsFJR1300]

I had a similar issue with my F150 but at 5300 RPM's(max RPM's are 5,900) last year. It'd fall back to about 4200 RPM's (ran fine up to 4,200 all day long)

Turned out to be spark plugs... They looked fine (actually like new). Put new ones in, (tighter end of spec), runs right up to 5,900 every time NOW...


You may also want to simply DRAIN the VST. Catch what comes out in a small clean container and examine it. If crap comes out, pump the primer bulb and try to flush until clean fuel comes out..

[bforsythe1]

crapping out F115

What do you mean by tighter end of spec.

[TownsendsFJR1300]

What do you mean by tighter end of spec.

The spark plugs will have a gap between a certain # and a larger # specific for your engine.

As the plugs wear, the gap gets larger over time. Set them at the tighter end of spec and they'll stay inside spec longer...

Mine is spec'ed at .039" to .043". I set them about .039" /.040"