4230 John Deere Fuel Delivery Issues

BimotaBiker

New User
My 4230 started hesitating when I increased or decreased the throttle so I changed the fuel filter hoping that it would alleviate the issue. However, nothing changed and the hesitation continued to grow worse over time. I unhooked the fuel line on the tank side of the lift pump and fuel poured out. I then unhooked the fuel line on the pressure side of the lift pump (at the pump) with the same results. The tractor starts but is virtually unresponsive to the throttle although the linkage is working properly. My grandfather purchased the tractor new in the early 1970's and it currently has only 3,300 hours on it. Am I looking at a new injector pump here?
 
My best guess is the governor ring has deteriorated ,& is starting to plug return line ,or check ball valve in elbow from I. pump to return line ; Check by taking return line from pump [put paper towel under it] , pull line from top for tank, blow com.air back thru line .. black on gray rubber specks on towel... I. pump g. rings do not age by tractor hours , but clock hours /years...
 
I would wonder if the lift pump has failed. If fuel pours out on the pressure side it is possible that the inlet check valve is staying open.
 
Sounds like the metering valve is sticking in the hydraulic head bore. Will not be a weight retainer ring failure as the 4230 DM pump didn't use one like DB, DC, JDB, or JDC pumps did. Early DMs had a larger metering valve that is more prone to sticking if traces of water is ever in the fuel. AC and White DMs have the same trouble. The very late pumps went back to the smaller valve like the other pumps have to help with the sticking problem. Valve can SOMETIMES free up by running the engine wide open, then QUICKLY turn the fuel stop lever off-on at the pump with the cable disconnected. This action makes the valve move, and with some lube added to the fuel there's a chance it will free up again.
 

One could loosen the 2 screws on inj pump timing window then pry gasket loose if stuck. If engine will then accelerate with window loose return line or fitting is plugged.
 
(quoted from post at 19:22:29 03/22/16) I would wonder if the lift pump has failed. If fuel pours out on the pressure side it is possible that the inlet check valve is staying open.

The lift pump sounded feasible and easy to change so I visited my local JD dealer and picked up a new lift pump (and fuel line since it developed a crack when I loosened it). After shelling out $120, I find myself in the same predicament with no improvement. I'll be trying more of your suggestions over the next few days. Thank you all for your suggestions and responses.
 
Those pumps were no good when they came out . Get your self a JDB pump and the lines and you will be good to go. You will have better starting, and idle, and more power .
 
(quoted from post at 19:14:12 03/22/16) My best guess is the governor ring has deteriorated ,& is starting to plug return line ,or check ball valve in elbow from I. pump to return line ; Check by taking return line from pump [put paper towel under it] , pull line from top for tank, blow com.air back thru line .. black on gray rubber specks on towel... I. pump g. rings do not age by tractor hours , but clock hours /years...

This scenario sounds feasible as well. My throttle response hesitates dramatically when the throttle is increased as well as being decreased. Would a plugged return line delay the engine RPM from returning to an idle when the throttle has been decreased?
 

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