Fuel Knock

[atvhauler]

I am getting a fuel/injector knock at low idle rev it up about 800 rpm the knock is gone. I try to isolate the knock with long screw driver and a stethoscope, no luck.
It does not smoke and has good power.Cold start up is also good. Any ideas?

 

[Burning oil]

Loosen each injector line one at a time while running/knocking and see witch one it is then r&r.

 

[THEFERMANATOR]

And if the noise doesnt go away when loosening the injector lines to isolate it, then you may have a broken nylon retainer for a rocker arm.

 

[atvhauler]

Loosen each injector line one at a time while running/knocking and see witch one it is then r&r.

Sorry I forgot to mention that has been done.

 

[Burning oil]

Sorry I forgot to mention that has been done.

obviously the knock did not go away then? Like Ferm said maybe rocker button. Long shot but maybe crank pulley?

 

[WarWagon]

Adding to the above check the flex plate for cracks. I would do a UOA to check the internals.

 

[Will L.]

I've seen a couple engines that had a mystery idle knock turn out to be a lifter that he some carbon partially plugging it. Found it by holding down pressure on the rocker arm.