Engine shaking

[RayK]

I have a G1700 Diesel, lately the engine shakes badly, I think its fuel so I changed both filters and it ran better for about an hour now were back to the shake. It seems to get worse as the tank gets low on fuel, I have used additive for water etc and can't see any dirt in the tank. Any ideas would be appreciated.

 

[locknut]

Vent on the fuel cap clogged up?

 

[whistlepig]

Probably sucking air in to a fuel line. Clean the motor thoroughly and dry it. Any place you see fuel leaking will be sucking air also.

 

[hr3]

You might check for a second filter.. My G1800 has 2 of them maybe yours does too..

 

[RayK]

Thanks Guys, I will try your suggestions I was thinking it could be sucking air but I can't see any fuel leaking. I did change both filters. could it be a weak fuel pump?

 

[jinman]

Ray, I would first check that the motor mounts are not loosening. If those are okay, then the Kubota Maintenance Manual says to check the following:

- Fuel filter clogged
- Air cleaner clogged
- Loose/leaking fuel connection to injectors
- Injector nozzle stuck/clogging
- Injector pump defective
- Fuel overflow pipe clogged (I think this is fuel return from the injectors)
- Governor defective

I would make sure all filters are good including the air filter and then look for leaks. If no leaks and you are sure fuel delivery is good up to the injectors, you might remove your injectors for inspection.

 

[grsthegreat]

does this happen AFTER blades are engaged, or while blades are not moving????

 

[RayK]

It shakes all the time,under power or not, it will run smooth for a couple of seconds then begin to shake badly then smoth out again, All the filters are good, guess injectors will be the next thing. thanks Ray

 

[jinman]

It shakes all the time,under power or not, it will run smooth for a couple of seconds then begin to shake badly then smoth out again, All the filters are good, guess injectors will be the next thing. thanks Ray

Ray, my G1800 does the same thing unless I keep the tank almost full of fuel. I think there may be intermittent power to the fuel pump. When I turn on the ignition, I can hear the fuel pump running, but when the engine is running and there is vibration from mowing, the fuel pump could be cutting out and I'd never know it. I just think what you are describing is a common problem with several models of Kubota Lawn Tractors that share similar designs. When the engine shakes and shudders, does it also lose rpm and power? Making sure both fuel filters are new and maybe checking to see the fuel pump is working by opening the outlet side and powering it up would be a good troubleshooting method. If you do that, you must hook up the pump again and bleed off all air at the outlet of the 2nd filter by the engine so that you don't send a slug of air to your injector pump. If that happens, you'll have to bleed air at the injectors to get the engine going again.

 

[RayK]

I blew the fuel injector return lines out back to the tank, now it seems to be running smother but it's low on power, also I noticed after starting it was puffing black smoke and I had very slow throttle response initially then it picked up rpm. Also should the electric pump run continually with ignition on and engine stopped, mine does now, seems before it would run until pressure built up and then stop, but I can't be sure of this.