F935 fuel issue

Turkeygrower18 · May 3, 2021

I have an f935 mower that I ran out of fuel. I got it bled and it starts right up but now I hear a knock while it’s running. It also smokes a little. But when I loosen the #1 injector (the one closest to the flywheel) the knock stops, it quits smoking and it idles smooth. What could be going on?

Zebrafive · May 3, 2021

It sounds like "rod bearing" is bad/knocking. When you loosen the injector line, that cylinder is not longer under load.
Did you spray with ether to try and start it? That could cause piston/ring problems and smoke. I don't know if that would also knock.

oldnslo · May 3, 2021

Is it possible that when ran out of fuel a piece of crud stuck number 1 injector open so dribbling fuel vs spray mist causing the smoking from unburnt fuel.

not sure if dribble would cause knock though

Turkeygrower18 · May 4, 2021

I should also mention that I’m not getting any fuel through the return line. Could there be dirt plugging the injector? Would that cause a knock? I did not use any ether on it

Zebrafive · May 4, 2021

Is swapping injectors an easy thing to do?
I am glad you did not spray it with ether!

Turkeygrower18 · May 10, 2021

Update: I pulled the fuel tanks and cleaned them. I replaced brittle pick up lines. Cleaned out all fuel lines. Then re-bled and ran injector cleaner through it and it changed nothing. So fearing the motor may be bad I thought what do I have to lose tearing into the injectors. Pulled #1&#2 when comparing the two I could not get the needle out of #1 but could #2 so after some carb cleaner I was able to get the needle out and it had a lot of gunk on it. Cleaned them both up ran it and it really smoked idling. But the knock seamed to go away. Reved it up and cracked the #1 line then tightened it and the smoking stopped and it ran smooth. I put some ATF fluid in with the fuel for some lubrication. It runs perfect and burns clear on high rpms but smokes and almost sounds like it’s flooding on idle.
The smoke smells like fuel not burnt oil. Could the injectors still be bad? Or still stuck open? Stupidly I didn’t pull #3