U302 diesel ideas wanted

dnd

Member
Hi, we have a U302 diesel, as a rule it starts right up. We use it to seed oats and pull a 12 foot drill. Last year after it was running about an hour or so it decided to just stop. Got it out of the way and let is sit for the day. Next morning it started right up. Thought problem was a typical issue we have been having with old Rosa Master pumps, so we pulled pump off and had local shop tear it apart, check over and replace the famous plastic parts that disintegrate. Problem solved we thought. Getting ready to plant this week, charged battery and it started right up. Again after an hour or so it acted like it was not getting enough fuel. Stopped in its tracks. Pulled it out of the way. I was seeding over at my place and about 4 my brother drives it over.
His thought is that there is a very small bit of air being pulled in through the primer which is right before the fuel filter. Has anyone had these primer pumps apart? I assume there is an orange or two inside. I dont think the primer can be bypassed as getting the fuel system bled would be a pain..
Any thoughts. Nice tractor and more than enough to pull the grain drill. I suppose I could always put a 12 volt pump on but wish to keep it as original as possible. Looks like Im going to need to keep it handy and rake hay once we determine whats happening.
 
Have you checked fuel flow? Changed fuel filter? Possible restriction in line or plugged elbow in bottom of fuel tank. I had same issue on G1000. Years of debris in bottom of tank was restricting line. Acted just like you describe. Our JS3 diesel has the same primer pump just before the filter. I rebuilt one on an IH 660 and seems like it was a rubber cup seal. I could still get the part from IH then but that was probably 20 years ago now.
 
I second the fuel flow/junk in tank idea. About two or three times a month someone posts a similar issues on YT, and it pretty much always turns out to be crap inside the tank/fuel tap.

Sometimes it's a little hard to diagnose, as it will flow fine when you test it after sitting. After running for a while, however, the whirlpool effect in the tank brings all the floating junk into the fuel tap where it blocks flow, until it's shut off and sits again, giving the junk time to disperse again.

My last three tractor purchases (Massey 555, Allis 180, Cockshutt 540) all had the exact same issue/symptoms.
 
Make sure the RETURN line is open, if plugged with broken retainer bits that will cause engine shut down too. Test by running until engine begins to slow down, then quickly loosen the two screw timing cover on pump side. If engine speeds up WITH the fuel leak, but slows/dies with cover tight there's a return restriction somewhere. Also check for any rubber supply line that could be swelled shut inside. Just had a JD 4630 with low power on the dyno, the rubber supply hose from final filter was almost closed inside, less than a pencil lead size when old hose was cut in two.
 

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