Hey all I had a quick question regarding my fathers 1977ish jd 350 crawler. It has a 3 cylinder diesel with a Roosa Master injection pump. The machine starts fine and idles great.. Heres the problem it wont take any throttle at all. Ive checked all the lines and linkage connections and everything checks out. This leads me to think that it may be internal. I am not familiar with Roosa Master pumps.. Any help would be much appreciated.

 

Is this something that started suddenly or was the JD sitting without starting for a long period? If so, how long? How fresh is the diesel in the tank? Have you added any diesel conditioner?
Have you tried starting it up, setting the throttle to about the 20-25% mark and then let it run for an hour to get everything as hot as possible?

 

Make sure the intake and air filter are not clogged and check fuel filter . I have had the return line on the Roosa master pumps get restricted and cause that problem also . On top of the pump there is a little check valve that maybe causing the problem on some Roosa Master pumps . Good luck with it and I hope this helped you some .

 

The machine did sit through the winter. It has been started and moved since, everything worked fine. Went out to use it the other day and she wouldnt take any throttle. I am assuming the fuel in the tank is from last winter as it is not my machine, we did add conditioner. Thanks for the fast responses guys

 

If you didn't already, throw a fuel filter at it and make sure its getting enough fuel and like said above the return isn't blocked.

After (you can try it before too) there is a little plate on the side of the pump with 2 screws holding it on, its called the timing window. Get a pan to catch the fuel that come out of here, we wouldn't want you to spill it on the ground now would we. Start the machine, set it around 1/2 throttle and just crack the window open and let some fuel run out. If the rpm's increase and the engine will "take throttle" then the problem is internal seals letting too much pressure into the wrong side of the pump.

Its a common problem with roosa masters that sit, there is a internal seal that dries out and literally falls apart. You can take the window off when the engine is not running and see if there is any bits of rubber there. I have no less than 2 here that have this problem and need a reseal.