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GarryinNC 08-30-2012 19:39:43 66.44.242.123 Report to Moderator	I am working on a friends JD 5320 tractor. It quit running on him the other day shortly after pulling it out of the shed. The fuse in the circuit the powers the injection pump fuel solenoid blew every time you turned the key switch on. I finally pulled the relay marked 'start bypass' and straight wired the pump to get it running temporarily. Today I did some more trouble shooting, thinking there might be a wire to the pump grounded some where. The pump has two wires on the hot terminal. The one from the switch turned out to be okay but the other wire goes up to a sensor near the top radiator hose. That wire is shorted to ground and was the problem. Left it unhooked, tractor starts and runs fine. Look this part up on the JD parts website and it is listed as a cold start advance sensor. Was just wondering it purpose(emissions or something else) and how it makes the pump advance. I assume it means timing advance. Will replace sensor, but in the meantime will it cause any problems to operate tractor without it hooked up? We live in North Carolina if climate is any factor. Thanks to any of you with knowledge about this. Garry [Reply]   [No Email]
jd5210 08-31-2012 04:32:33 71.254.70.135 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to GarryinNC, 08-30-2012 19:39:43   On the thermostat housing there is a sensor that is connected to a two wire harness that goes to the injection pump; this is the "cold start advance" portion of the system so it starts easier when cold by advancing the timing. If you disconnect the sensor and it works fine ohm test the sensor, probably shorted. The sensor on the thermostat housing controls the advance on the injection pump. When it fails it shorts out and blows the fuse. Try unplugging it, replace fuse and see if it starts and runs. The part # is RE503242, if you are quick changing it, you don"t have to drain the coolant, just make sure it"s not hot at the time. You will want a pan under the tractor to catch the coolant, so as not too have to clean it up. To comply with the exhaust emissions regulation, the timing of injection pump should be around 6 to 9 degrees before TDC. This timing values do not allow proper start-up operations when engine is cold. To ease engine start-up, a cold advance system gives to the injection pump a temporary over-timing. [Reply]  [No Email]
GarryinNC 08-30-2012 20:18:35 66.44.242.123 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to fixerupper, 08-30-2012 19:39:43   Thanks for the fast replies! I did some more research in the mean time and found this to be a fairly common problem. Will replace the sensor for him when I get a chance and leave it unhooked for now. I read these forums just about every day for learning and entertainment. It is a way to relax for me. Beats the heck out of TV, newspapers etc.! Thanks Again, Garry [Reply]  [No Email]
tractorfixer1 08-30-2012 20:07:53 184.36.190.219 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to GarryinNC, 08-30-2012 19:39:43   On the thermostat housing there are 2 temp. sensors. Unplug the larger of these. The wires are hooked into the injection pump timing advance for cold start. If fuse does not open now, either replace the sensor or leave it unplugged. [Reply]  [No Email]
tractorfixer1 08-30-2012 20:09:33 184.36.190.219 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to tractorfixer1, 08-30-2012 20:07:53   Sorry did not read the whole. [Reply]  [No Email]
Rick in SC 08-30-2012 20:04:15 206.74.133.220 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to GarryinNC, 08-30-2012 19:39:43   I know of several of the 5000 series tractors that have had this problem. I think the switch advances the timing slightly when cold to help with emissions and it may make it run smoother while warming up. In NC I don't think it will cause you any problems. In fact I doubt that it would cause any major issues in any climate; might just smoke a little more when cold. [Reply]  [No Email]
DEEREMEYER1 08-30-2012 19:45:37 71.50.25.139 Report to Moderator	Re: JD 5320 Question- JDSeller or others in reply to GarryinNC, 08-30-2012 19:39:43   Don't quote me on this but I believe there is an electric solenoid in the injection pump that moves the cam ring a tiny bit to change the timing when it's energized, or something along that line. [Reply]  [No Email]