Bobcat E35 will not maintain RPM

raysmithtx · Sep 24, 2018

Was digging stumps at full power and after about 30 minutes the engine RPM dropped to idle even though the power was turned all the way up. Could turn the power knob down to idle and back up and the RPM would increase for about 5 seconds then drop to about idle speed again, even though the power knob is at full power. I'm new to this whole excavator thing and would appreciate some suggestions here. Thank you.

Jabonee · Sep 26, 2018

Kubota or Doosan engine ? :confused3:

dadster4 · Sep 26, 2018

RPM's are limited by fuel delivery, check flow into and out of the fuel filter. Could be debris in fuel tank or dirty filter, both easy to check before getting more involved.

thepumpguysc · Sep 27, 2018

U said u turned the "KNOB".. is the throttle actually moving down to low idle or is it poor fuel delivery. Your gonna have to LOOK & see.

Jabonee · Sep 27, 2018

raysmithtx said:
Was digging stumps at full power and after about 30 minutes the engine RPM dropped to idle even though the power was turned all the way up. Could turn the power knob down to idle and back up and the RPM would increase for about 5 seconds then drop to about idle speed again, even though the power knob is at full power. I'm new to this whole excavator thing and would appreciate some suggestions here. Thank you.

I'm guessing by now you realized you had the "auto throttle " turned on. :confused2:

raysmithtx · Sep 29, 2018

Thanks for the helpful replies to my question. I thought the problem might be fuel related so I replaced the fuel filter. Then when I squeezed the primer bulb to remove the air, the primer bulb would not re-inflate. So I figured I had a fuel line blockage. I found some 'gunk' in the fuel pick up tube. It appeared to be a sort of foam rubber/sponge like material. I bought the excavator used and could see that that at some point the tube clamp had been replaced so there has been some sort of problem in the past. .

The problem is that the fuel line has clogged twice since then.

I am thinking about cutting a 2" hole in the top of the fuel tank (it's plastic) and using a shop vac to vacuum out the debris in the tank. Then using a 'expansion hole plug" to seal the hole in the tank back up.

I am open to other ideas on how to remove the gunk if anyone out there has any ideas.

thepumpguysc · Sep 29, 2018

Have u heard of a "suck bucket"?? I don't know if u can google it or not but what it is is.. u take a 5 gal bucket w/ a lid..say a 5 gal oil bucket.. u put your shop vac noz in the pour spout & cut a small hole for another length of hose in the lid.. you use that smaller length of hose to do the actual sucking.. THAT WAY you can get in the tight spaces & the gunk ends up in the bucket & not your shop vac..
For best results tape all the connection points on the lid..
I hope this helps..

raysmithtx · Sep 29, 2018

That's a great idea. I think I'll use a length of copper tubing attached to a plastic hose so I can get into all the corners and edges. Lots of good info and helpful people on this forum.

Deerherd · Sep 29, 2018

I have an E42 Bobcat and it does the same thing, it is a feature not a problem.

If I do not do anything, it will drop to idle. Moving the controls makes it jump back up to the previously set throttle speed.

Next time it drops to idle, just move the controls.

I surely would not be dredging out the tank.