I have a Dura Tech tub grinder with a 4039T John Deere engine and for some reason I can't figure out the fuel tank is not venting and so much suction is created in the tank it bogs the engine down and the engine overheats. It looks like there are small holes in the fuel cap but they are not plugged that I can tell but it seems like they would draw air into the system if they are the only vent. I don't know much about diesel engines so I could use a little help please. One fuel line goes from the tank to the fuel pump then to the injector pump. The other line is at the top of the fuel tank and goes from the tank to the fuel rail on the top of the engine. Any ideas what could be causing this? It seems like a venting issue to me but where? I took the return line( I am assuming) off and wen I crank the engine over fuel dose come out but not much. Should there be a lot of pressure her or is just a little fuel coming out normal? Any help would be appreciated.
A quick test would be to crack the fuel cap and operate the grinder. This will allow the tank to vent and then you can see it the engine bogs or not. I think you will find the overheating problem is the radiator needing blown out. Are you grinding mulch with this unit? The return line will have little fuel and almost no PSI.
I have never experienced overheating from fuel starvation in a Deere. Clogged air will cause both overheat and decrease in rpm while under load.
I would have dealer check the injectors on this unit, check to see if its still under warranty. As an OEM application like you have here it should be 2 years.