Roosa master DBG pump not pumping fuel

[cannoncollector]

I just bought this 1966 Allis Chalmers hd4 and the Roosa master dbgfc fuel is just not going through it , any ideas? I checked the inlet screen I pulled the top cover everything looks free but a little rusty..yes the machine has been sitting not running for some time the history is really unknown

 

[cannoncollector]

really want to hear it run!

 

[Dieseltech]

If it's set awhile like most I see it will have several critical parts stuck inside, plungers, metering and delivery valve. After a complete tear down, cleaning and reseal most can be re-calibrated fine on the test bench..

 

[JDEM]

If it has stuck plungers from sitting, sometimes all it takes is compressed air to get it going, fed in backwards. That is the way Allis Chalmers "air times" that pump anyway. #1 make sure the pump is actually turning inside and the shear-shaft type driveshaft is not broken. If OK, #2 - take the top cover off and make sure the metering-valve is in "run" position If yes, then #3 is hook an air-line to one of he injector discharge ports with over 100 PSI. Then rotate the pump until that port is in "inject" position and the air will be directed to the pump plungers and might free them is stuck.

The "pump" is really two pumps inside a container. One low pressure rotary-vane pump that must sent low-pressure fuel to the other high-pressure piston-pump. If a piston is stuck, it will not pump any high pressure fuel.

 

[cannoncollector]

Great information JDEM!!, I'm going to try that today....I was using compressed air but not backwards, I should have thought of that!!

 

[Ragnarok]

Not something really stooped wrong...like some of those old Allis tractors that have the kill cable that needs to be pulled out to turn on the fuel rather than pushed in like everybody elses kill-cables???

 

[prairiebreeze]

I have been reading for a while and messing around with my Hough loader and the pump. Like many others on here, it ran when I parked it over a year ago. Went to fire it up again and there was no fuel to the injectors. The metering valve seems to be free as it move back and forth easily, my electric lift pump is supplying pressure, I opened the timing "window" and it is turning fine. I do have a small amount of diesel coming out of the return line. I have loosened the injector lines at the pump and removed the glow plugs and still no fuel coming out of the injector lines? Does pressured air really work to loosen the plungers if that is the issue?

 

[Powered By IH]

Does pressured air really work to loosen the plungers if that is the issue?

Only one way to find out.

 

[m16ty]

I have been reading for a while and messing around with my Hough loader and the pump. Like many others on here, it ran when I parked it over a year ago. Went to fire it up again and there was no fuel to the injectors. The metering valve seems to be free as it move back and forth easily, my electric lift pump is supplying pressure, I opened the timing "window" and it is turning fine. I do have a small amount of diesel coming out of the return line. I have loosened the injector lines at the pump and removed the glow plugs and still no fuel coming out of the injector lines? Does pressured air really work to loosen the plungers if that is the issue?

I've never tired it but in theory it may work.

I know how to work on them so I just pull the pump, take it apart and clean it. With modern diesel, I do know that especially the Roosa Master/Stanadyne pumps, if they sit too long the fuel plungers will stick.

 

[prairiebreeze]

That is probably what I need to do. I have tried a few things without success so probably just needs to be pulled. Thanks.

 

[used red MN]

That is probably what I need to do. I have tried a few things without success so probably just needs to be pulled. Thanks.

Hello PB, welcome to YT! Just FYI if you are looking for someone to work on the pump for you a member here that goes by Dieseltech work on them for many on here. You would be shipping it to Ohio but even with that his charges are very reasonably and he does excellent work. Contact him via a Direct Message accessed by the mail envelope above.