1256D hard starting

GeoM0 · Jul 28, 2010

My sons 1256 will start good cold but will not start without a shot of either after it has warmed up. Engine turns over fine and pump has be rebuilt.
Thank You

Brian Bell · Jul 28, 2010

Is the starter spinning it fast enough after it gets hot? I had a JD2240 that would start great cold but was a bit of a pest when hot because starter was dragging. Also make sure all of you battery connections are good and clean and tight.

Owen Aaland · Jul 28, 2010

(quoted from post at 15:48:10 07/28/10) My sons 1256 will start good cold but will not start without a shot of either after it has warmed up. Engine turns over fine and pump has be rebuilt.
Thank You

Do you get smoke out the exhaust while it is cranking? Did you have the injectors rebuilt? If the pump is getting on the weak side it may not be able to create enough pressure to open the nozzles when the fuel is warm. If that is the case you will either need more pump work or lower the opening pressures in the nozzles.

One other thing, if your pump has a recirculation line on it from the engine side of the pump to the inlet fitting it should be removed. I do not know when the change was made to eliminate it but the 06 models with RoosaMaster pumps came with the line. The idea was to recirculate the fuel without returning it to the tank to avoid going through the filter again. It was an attempt to get longer life from the fuel filters. The result was hotter fuel in the pump with loss of power and hard restarts when warm.

pete 23 · Jul 28, 2010

I notice you said pump was rebuilt, if that is the case I would look for a loose screw on the delivery valve stop or sticking pumping plungers which would both fall upon the hands of who ever rebuilt the pump. Normally, hard start cold means engine or cranking problems, hard start hot, worn out pump or internal leak in pump. That screw likes to for some reason work loose, never has on one I was into but have seen it and heard of it many times on others. Of course, the stop plug needs to be replaced when ever the delivery valve is removed from rotor or it can leak even with a tight screw. Just a couple of many things that can give you a problem. Way back in about 1961, when 560's were still current new tractors, at a service school they bugged one just that way also, it started right up cool, but you could not get it to fire up when warmed up and they had much lower injection pressures than a 1256.

GeoM0 · Jul 30, 2010

No smoke. Motor turn over fast enought and we have jumpered w/ 3 batteries turning it faster than normal. Hope it is the return line
Thank you

1256D hard starting

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Brian Bell

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Owen Aaland

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