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John Deere 620 engine hunting

J

JDtractormanalb

New User
Hi,
I have a John Deere 620 gas tractor.
Iis hunting both on idle and at other throttle settings, the only time it wont hunt is when i have the choke half way out.
I have disconnected the governer linkage at the carb and felt the movement from the governer when adjusting the cabi valve by hand, there is a bit of movment in the governer from when it want to open the throttle and wants to close it.
im guessing the governer weight pins are worn.
is there anything else i should check before i pull down the governer?
 
The carburator has some dirty or clogged passages. It needs to be removed,and cleaned properly. I think once the carb is rebuilt you will find the governor is fine.
 
I'm not familiar with your tractor, but hunting is often caused by a blocked idle circuit in the carburetor. The fact that it runs better when the choke is out would support that diagnosis.

Before tearing into the governor, figure out why the engine won't idle; the governor shouldn't be doing anything at idle.
 
Gasket leaking air between carb & manifold will cause hunting as mixture is always changing. Can check gasket by spraying starting fluid on gasket. If engine speed increases you have a leak. If not, dive into the carb. Good luck- joe-
 
BEFORE I tore into the govenor I would manually control the carbs throttle by disconnecting its linkage to the govenor and see if she will run and idle down smoothly. If not and she still seems to die out UNLESS you bump up the RPM (what the govenor does if she slows down) or requires choke to run properly I THINK ITS A CLOGGED CARB PASSAGE PROBLEM NOT THE GOVENOR. However, if it will run n idle smooth by manually controlling the throttle but hunts ONLY when govenor is atatched I THINK ITS A GOVENOR PROBLEM.

I like others suspect the carb more then the govenor from what you said UNLESS its a vacuum leak (manifold or carb or manifold gasket) and shes sucking in air causing the mixture to lean out as posted below.

John T
 
Pulling the choke is the clue.
Over the past 52+ years enough dirt,rust and gasoline goo has plugged the idle passages. There are three tiny little ports per side that are easy to miss.
Tossing the carb in a bucket of cleaner and blowing compressed air will do nothing. The steel balls may have to be pulled and the main idle passages rodded clean. Then using something small and soft to avoid burring or oversizing the six wee passages.Clean them out too.
Is the gasoline screen in the carb rusted through and let dirt in? Is the sediment bowl screen intact?
 
Hi thanks for the help, and the suggestion about the carbi.
over the last few nights, with the help of a workshop manual I pulled down the carbi and found that moisture had been laying in one of the barrels and blocked up the idle ports with rust.
gave it a good clean up and put it back togother, and now it runs very well.
many thanks again.
 
Hi thanks for the help, and the suggestion about the carbi.
over the last few nights, with the help of a workshop manual I pulled down the carbi and found that moisture had been laying in one of the barrels and blocked up the idle ports with rust.
gave it a good clean up and put it back togother, and now it runs very well.
many thanks again.
 
Hi thanks for the help, and the suggestion about the carbi.
over the last few nights, with the help of a workshop manual I pulled down the carbi and found that moisture had been laying in one of the barrels and blocked up the idle ports with rust.
gave it a good clean up and put it back togother, and now it runs very well.
many thanks again.
 
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