JD 650 Governor/Injector pump issue

So I inherited my grandfathers 650 when I purchased his house last year. He passed back in 2011 and nobody did anything with the house or tractor in that time.

Needless to say, the tractor has been sitting for the last 9-10 years in the garage not running because of some issue. When looking at it further after two other family members had looked at it over the last 10 years, I found the injector pump rack seized. I took apart the front timing cover to get it out because of the position the rack was stuck. I disassembled the pump, put all the parts in an ultrasonic parts cleaner, reassembled it and as smooth as new. Replaced a few other maintenance items, belt, hoses, thermostat, fuel filter, oil change, battery, etc.

Bled the fuel system went to start it and the engine decided to runaway. Was able to kill the fuel valve on the filter housing which cause the engine to shut down, luckily.

I cannot figure out what went wrong here. Any advice would be greatly appreciated. The tractor is a 1987 and has ONLY 200 hours on it. I can remember riding on it as a child with my grandfather and would love nothing more than to get her going again.

Sounds like the plungers are installed backwards..

(quoted from post at 18:24:38 06/14/20) Sounds like the plungers are installed backwards..

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So just pull the pump swap the plungers and try again?

If you're SURE the governor is right. All inline pumps have barrels and plungers mated to each other, Bosch P size pumps plungers are non directional, will work either way as barrel has two holes and plunger has two helix to control fuel delivery. Other inline pumps the plungers are directional, barrel has one hole and plunger has one helix. Plunger helix MUST be on the barrel hole side to control fuel delivery, installed 1/2 turn off places helix away from barrel port, meaning NO fuel control at all. So, if EITHER plunger is installed 1/2 turn off, OR the barrel installed 1/2 turn off WILL cause no fuel control.

(quoted from post at 18:59:43 06/14/20) If you're SURE the governor is right. All inline pumps have barrels and plungers mated to each other, Bosch P size pumps plungers are non directional, will work either way as barrel has two holes and plunger has two helix to control fuel delivery. Other inline pumps the plungers are directional, barrel has one hole and plunger has one helix. Plunger helix MUST be on the barrel hole side to control fuel delivery, installed 1/2 turn off places helix away from barrel port, meaning NO fuel control at all. So, if EITHER plunger is installed 1/2 turn off, OR the barrel installed 1/2 turn off WILL cause no fuel control.

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That makes perfect sense. Thank you very much. It is quite possible I installed the plungers backwards. I had never rebuilt one of these pumps before and while putting it back together I questioned which way they went back in. The governor assembly seems perfectly fine thats why I was going crazy. Thank you again for taking the time to explain I will be taking the pump apart next weekend and will let you know what the outcome is.

Being in diesel pump repair over forty years and counting, I've seen it happen before. Also if the rack and gear segments are not meshed correctly, that will cause trouble too. Some pumps use ball end with rack notches to eliminate the problem gears/rack teeth misalignment..

The rack and gears had marks for alignment, that I picked up on. The plungers definitely had me unsure.

(quoted from post at 18:59:43 06/14/20) If you're SURE the governor is right. All inline pumps have barrels and plungers mated to each other, Bosch P size pumps plungers are non directional, will work either way as barrel has two holes and plunger has two helix to control fuel delivery. Other inline pumps the plungers are directional, barrel has one hole and plunger has one helix. Plunger helix MUST be on the barrel hole side to control fuel delivery, installed 1/2 turn off places helix away from barrel port, meaning NO fuel control at all. So, if EITHER plunger is installed 1/2 turn off, OR the barrel installed 1/2 turn off WILL cause no fuel control.

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Just so Im clear the barrel hole needs to be on the side of the fuel supply line for the pump AND the helix on the plunger needs to be inline with the barrel hole?

The plunger helix area MUST be next to the barrel port no matter how the barrel is located in the housing. The rack rotates the plunger as needed to increase/decrease fuel delivery per governor control. When plunger helix is away from barrel port max fuel is delivered, with NO way to stop engine unless injector lines are loosened or engine air is shut off.

(quoted from post at 08:17:25 06/15/20) The plunger helix area MUST be next to the barrel port no matter how the barrel is located in the housing. The rack rotates the plunger as needed to increase/decrease fuel delivery per governor control. When plunger helix is away from barrel port max fuel is delivered, with NO way to stop engine unless injector lines are loosened or engine air is shut off.

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Got it. Im pretty sure the barrel only fits in one way due to set screws located on one side of the pump housing. Im becoming more and more certain I just have to rotate the plungers 180 degrees to line up the helix. Thank you again for all your information. I will post back Wednesday afternoon once I get a chance to work on the tractor.

Well sure enough the plungers were in backwards! Got her started this morning only issue now is I cannot get it to hold a slow idle. It will run steady at 1500 rpms but anything lower its all over the place and wants to stall. Suggestions?