Got one like an 05 model John Deere engine. Fuel is bleeding off when not in use, if it sits a few days you'll have to pump the manual pump and open line out of filter to get it to bust off. It has the little manual pump on the side not the pump on top of filter housing. The manual pump that you press to pump it up doesnt feel real strong but it will pump. So is it the pump, filter base or a combination? Thanks. I think it's the 4045T engine. 100 Hp turbo.
Ok I'll answer. None of the above. The little grommet that seals the line feeding the injection pump was bad. I noticed wet fuel around the pump. Didn't have another one so I cut a piece of 3/8 fuel line (a little sliver) and made one. I will of course get the proper seal, but it works! I'm da man!
Often it's the little things that will kill and engine. It sounds like you're describing those lathe cut seals used on fuel lines. Those pieces of rubber get hard as a rock from heat and the fuel, most likely your injection pump was sucking air. You should be able to get those seals at any injection pump shop. Good job on the fix. :drinkup