720 diesel slow to drop rpm

JLG · Jul 5, 2015

If my 720 diesel is at fast idle and I pull the throttle back, it's slow to drop rpm. What would cause this?

The fuel screw has been adjusted out. I haven't tried screwing that in yet. Don't know if that will change anything or not. I've had this tractor a year and have been trying to get the fuel system straightened out, off and on, ever since.

Thanks!

Dieseltech · Jul 5, 2015

May be as simple as the eccentric pivot arm incorrectly set, or more serious as flyweight trouble. Governor spring increases speed, flyweights return rack to no fuel position when spring load is reduced, and they balance each other to hold a given speed when system works correctly. Could also be a sticking rack, just one sticking plunger would cause it. On any inline pump the rack must move freely.

mjbrown · Jul 5, 2015

Cheap easy things first. Rack movement must be smooth. Check the spring that pushes the rack back to idle. Work back from there.

JLG · Jul 18, 2015

Thanks for the help! Took the pump apart. Barrel in #2 pump was tight in it's fit. Book says there should be slight movement even when the barrel locating screw is in. Pulled the barrel out and found a tiny piece of wire on the outside. Put it all back. Barrel has slight movement now. Started it and tractor now comes down to idle now like it should.

We think the previous owner had a fuel filter come apart. i just bought it and Ive previously had injector tips and the pump bridge clogged with the same material. Took them apart and cleaned everything and blew out the fuel lines. I didn't take the barrels out though, didnt think anything could get in there. WRONG!

720 diesel slow to drop rpm

JLG

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Dieseltech

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mjbrown

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JLG

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