930 case diesel pump question.

Mack10

New User
Working on a 930 with the online Bosch pump. Have changed all filters and cleaned the tank. It will run til the filters run out. Wondering if supply pump is bad. Replaced just about everything. Kinda stumped.
 
Hand pump is worn out will not pump filters full. Put o ring in to seal it off. Don't believe the supply pump is working.
 
There are two check valves on the supply pump, if one or both are stuck on their seats the pump won't move fuel. Had a supply pump in an IH truck with the Bosch MW inline awhile back, stuck valves were the trouble on it. The valves are under each of the two 19 MM cap plugs on top of the supply pump. There is a small spring on each valve too.
 
Add an electric fuel pump back by the tank. It only needs about 3 PSI it will solve a lot of issues with bad lift pumps
 
There is a small check valve on each end of the hand pump. Check to see if they are plugged up. If the fuel does not run out of the bleeding plug of the first stage filter when the fuel tank is full the elbow out the bottom of the tank could be plugged.
 
Thanks for the info. Very possible that's the problem. Got a lot of junk out of the tank and lines. I suppose that pump will come off without taking the injection pump off. Gonna try that next.
 
you said you got lot of junk out of tank so if you havent do take the hand primer apart an totally clean it .You can remove the line goint into the first filter an you should get full flow of fuel also. Easiest stuff first.
 
there isnt any lift pump on that engine. your problem is probably gonna be crud stuck in the elbow on the tank take the line loose at the filters you could also try blowing compressed air back through the lines.
 
Done all that. Fuel runs freely to the first filter. I can prime her up and it will run like a champ for a few minutes and it just runs out of fuel. Makes me believe the supply pump is not working. The tech manual I have says you should be able to feel a pulse in the return line. Not feeling it.
 
no lift pump? the injection pump has a lift pump built onto it between the pump and the block, that is something I would check, there is no need for an electric pump or other things that will give you trouble down the road, that fuel system has worked as is for 50 years and will continue to do so once the problem is found
 
the injection pump has to come off to get the lift pump off, any injection shop should have re-built units available, the hand pump is not supposed to be servicable but I have drilled off the riveted head on the knob so I could replace the o-ring on the piston I then drilled and tapped the stem so I could install a machine screw to hold the knob on
 
I agree, don't like putting electric pump on there. I know it will run if I can find the problem and fix it. Gotta be the lift pump. Was hoping to get it off without taking the injection pump off. Maybe not.
 
Your probably on the right track.If the transfer pump is working you should feel pulse on rubber hose from final filter to pump.I think if you cracked bleeder on final filter it would squirt out also.I dont know if Case ever put the filter housing that has two filters on it that had a T handle valve that you were to use to bleed filters like my 830 has but if so it needs to be closed to run.Its purpose was to allow fuel to fill all 3 filters by gravity .It allowed fuel to bypass the little transfer pump.
 
If you remove the injection pump be sure to have it at correct timed position so it will be easy to reanstall.( timing mark on pulley at correct position an slash marks on injection pump matching.)
 
Just a word on the 930. I took the hand pump apart. There was an issue with one of the check valves. Was not able to get one. Didn't want to but the whole pump. Got to thinking about the 83I'd I used to have and remembered they didn't have the hand pump. I took the valves out of the hand pump and she runs like a champ now. The one valve was restricting the fuel and now it runs fine. The problem was the hand pump.
 
Well the problem was the hand pump. I took it apart and the check valve on the intake side was stopped up and damaged. Got to thinking bout the 830's I used to have. They didn't have a hand pump. So I took the inner parts out of the pump and put it back on and fuel ran out the bleed screw on the primary filter. Primed her up and she runs like a champ. I suppose the hand pump is not necessary for it to run. It started and been running ever since.
 

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