855 runs rough at certain rpm's

[kimodc]

Hello,
My JD 855 runs very rough and shakes between 1100 and 1450 rpm, and then as soon as I hit 1500, it smoothes right out. I have run fuel injector cleaner through it and it did not seem to make any difference. Any suggestions as to why this might be happening, or any ideas how to get it running smoother?

 

[kuboman]

Hello,
My JD 855 runs very rough and shakes between 1100 and 1450 rpm, and then as soon as I hit 1500, it smoothes right out. I have run fuel injector cleaner through it and it did not seem to make any difference. Any suggestions as to why this might be happening, or any ideas how to get it running smoother?

Does is smoke blue smoke when it is running rough?
Likely is dirty injectors and it takes many hours of using injector cleaner to clean the injectors and it is possible that they may need to be rebuilt.:thumbsup:

 

[kimodc]

I haven't noticed any blue smoke when it is running rough. I have run cleaner in the fuel for probably 10 hours now with no change. Would dirty/worn injectors do that- run rough at only certain rpm's?

 

[kuboman]

I haven't noticed any blue smoke when it is running rough. I have run cleaner in the fuel for probably 10 hours now with no change. Would dirty/worn injectors do that- run rough at only certain rpm's?

They can, it can also be worn delivery valves in the IP but usually if the IP is worn the injectors will be to. Before I took the IP out to get checked I would pull the injectors and have them checked at a pump shop. The fuel system is one the most neglected and abused systems on these small tractors and for some reason they have one of the poorest filtration setups. Which is quite dumb considering that the repairs costs are the same as they are for a much larger engine.:confused2:

 

[JDG]

My 855 service manual list the low idle at 1400-1500 rpms. Check your your throttle cable housing for rust causing the hand throttle to be out of adjustment.

 

[kimodc]

Now it has really started acting up! It will run okay for a 10-20 minutes, then acts like it is starved for fuel and quits/barely runs. After letting it sit for half an hour while I checked the fuel filter (which was installed upside down) it started up, ran fine, then quit again 20 min later. It sounds just like a clogged fuel line which opens up and runs fine for a while only to clog back up again.

 

[JDG]

When it stalls can you see fuel around the filter? When you changed the fuel filter was there good flow coming from the tank? Check the vent in the fuel cap and the seal between the fuel bowl and fuel bowl housing. Also did you bleed the fuel system after changing the filter?