The dozer will work for a couple of hours then the engine will totally die / stop every 10 to 20 minutes. When you jump out to use the priming pump there is a strong vacuum at the priming pump. The vacuum disappears after the pump is pumped 15 to 25 times. Once the vacuum disappears and the priming pump creates pressure, you can hear the fuel going back into the tank I have blown back to the tank with a compressor and that appears clear. The engine starts no problem once there is pressure. Is there a valve that could be broking the fuel flow ?
kinda sounds like the tank air vent is plugged
Petepilot, exactly what I thought. Those vent in the cap.
I have cleaned out fuel tank breather. When I take the fuel tank lid off there doesn't appear to be a vacuum. I was wondering if there was a one way valve that could of collapsed near the fuel pump.
The Cat gentleman would like a serial number and a history of the machine as possible. It seems you have determined there is a lack of fuel on the supply side. A restriction possibly. You need to evaluate everything on that side. From my reading here fuel filters, water separators, in line screens, banjo joints fuel tank screens fuel tank full of junk and more. Sometimes lines collapse. Blowing backward doesn't solve the problem just pushes it back. You need an operation and maintenance manual and a service manual. Wishing you well.
Just to explain why we like serial numbers. This is what shows up on SIS for someone in the USA and I would not be surprised if there are more Prefixes for model in other countries. TRACK-TYPE TRACTOR Model Prefix D6D TRACK-TYPE TRACTOR 01Y D6D TRACK-TYPE TRACTOR 03X D6D TRACK-TYPE TRACTOR 04X D6D TRACK-TYPE TRACTOR 05X D6D TRACK-TYPE TRACTOR 06X D6D TRACK-TYPE TRACTOR 19B D6D TRACK-TYPE TRACTOR 19X D6D TRACK-TYPE TRACTOR 20X D6D TRACK-TYPE TRACTOR 30X D6D TRACK-TYPE TRACTOR 31X D6D TRACK-TYPE TRACTOR 32X D6D TRACK-TYPE TRACTOR 33X D6D TRACK-TYPE TRACTOR 36C D6D TRACK-TYPE TRACTOR 37C D6D TRACK-TYPE TRACTOR 38C D6D TRACK-TYPE TRACTOR 5YB D6D TRACK-TYPE TRACTOR 6HC D6D TRACK-TYPE TRACTOR 74W D6D TRACK-TYPE TRACTOR 75W D6D TRACK-TYPE TRACTOR 7YK D6D TRACK-TYPE TRACTOR 9FK D6D SR TRACK-TYPE TRACTOR 7XF When to add in that any one of those prefixes could have several serial number changes, for example the 31X comes back with three serial number breaks, it gets to be a guessing game to give any real help. Sure one can say check for something plugged or dirty but that's about the only thing. If for some reason a S/N can not be found a couple pictures of the fuel system and tank can give at least an idea of how the machine is built.
One thing you can do loosen fittings starting at the tank when you find the one that releases the vacuum you have a path to work on It could be a floater in the tank even that moves away from the suction when not running and vacuum is released We had a 950 recently that had nasties jammed up inside the primary filter head so changing filters would get it running until the particles aligned properly to block the flow again
Totally NOT Cat but I had a problem with my old Farmall BN tractor I mow the large areas of the lawn. A couple times it acted like it was running out of fuel but then when I got to the barn to fuel it up found it to have at least three inches of fuel in the tank. After the last time I decide it was past due to check this out. Sure enough when I drained tank and removed the sediment bowl found about half a teaspoon of flecks and strips of sealant stuck in the shut off valve. The thing would run perfect for an hour or more mowing but then those pieces of crap would get all lined up right and kill the engine. Then when fuel flow stopped or I closed and reopened the shut off valve they would float around and let the fuel flow again for another hour or more! So I'm thinking it is something like this on this D6D just would like to be ble to look at the exact layout of the fuel system to be able to guess where the most likely place would be.
Could be panties .......... Air compressor .. college town.. panty raid.. me with a coat hanger..