7040 Injection pump

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   I’ve got two 7040s one was a non runner as it wouldn’t pump any fuel so removed the pump to clean it and prior to removal I noticed the advance trimmer screw was screwed out a long ways. Upon tear down it had an extra spring on the other side of the advance as well. Popped the plug out of a parts engine that was running and it didn’t have a spring on that side as I thought all dm pumps only utilize the one inside of the advance piston. Looked in the parts book and it didn’t show anything extra. The way I understand it to work is they almost had the advance locked out any ideas as to why it would’ve been that was 

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AllisandGleaner Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 04 Mar 2016 Location: Sc Points: 356	Post Options Post Reply Quote AllisandGleaner Report Post Thanks(0) Quote Reply Topic: 7040 Injection pump Posted: 23 Mar 2025 at 8:49am
	I’ve got two 7040s one was a non runner as it wouldn’t pump any fuel so removed the pump to clean it and prior to removal I noticed the advance trimmer screw was screwed out a long ways. Upon tear down it had an extra spring on the other side of the advance as well. Popped the plug out of a parts engine that was running and it didn’t have a spring on that side as I thought all dm pumps only utilize the one inside of the advance piston. Looked in the parts book and it didn’t show anything extra. The way I understand it to work is they almost had the advance locked out any ideas as to why it would’ve been that was

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DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 21236	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 23 Mar 2025 at 11:14am
	That's the way I did my DM-4 tractor pulling pump. Screwed the advance screw all the way out to hold it at zero timing. Retimed the injection pump at 36 degrees BTDC instead of 18 degrees BTDC.

AllisandGleaner Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 04 Mar 2016 Location: Sc Points: 356	Post Options Post Reply Quote AllisandGleaner Report Post Thanks(0) Quote Reply Posted: 23 Mar 2025 at 11:32am
	I guess that would make sense if this was a pulling tractor but it’s a farm tractor and timing was still set at 18 degrees. What kind of performance would this thing have had in the field the way it was set up?

DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 21236	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 23 Mar 2025 at 11:46am
	I don't know for absolute surety what has been done to the pump, as I'm not there looking at it. If it is timed at 18 degrees BTDC and the advance cannot work (or advance the timing) the engine will not run with good power, have extreme high exhaust temps and eventually would melt pistons. The 7080/7580 DM-4 631 pumps had a different advance than a 7040 DM-4 629 pump.

AllisandGleaner Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 04 Mar 2016 Location: Sc Points: 356	Post Options Post Reply Quote AllisandGleaner Report Post Thanks(0) Quote Reply Posted: 23 Mar 2025 at 12:32pm
	It’s got the correct 629 pump. The previous owner said they used to run the tractor and the pump had stuck from sitting. Im thinking the pump must’ve been tinkered with somewhere along the lines as it had none of the wire seals on it.