Farmall MD injection pump

[grandad1066]

Got a MD that has sat for 20 plus yrs. Got gas side working and cleaned diesel side up as far as filters and cleaned tank. I am a mechanic myself just not too familiar with injection pumps. So I first unhooked throttle and checked rack. Throttle moves free about 3 inches and has some spring resistance at the end, which I think is the governor spring compressing inside.
All was good so I ran it on gas, bled the filters and switched er over and took right off perfectly. But it has a miss on number 4. Inconsistent miss so I added about a gallon of transmission fluid to 5 gal of diesel and have ran it for about 3 hrs. Misses always at wide open and intermittent at slightly above idle. What I found is that by cracking bleeder it is only shooting fuel about every other time it should be and it doesn’t seem to have much pressure at bleeder. Removed the injection line right at pump and started it up and still, about every other or every 4th time it should shoot fuel it squirts a little bit out. I know this by comparing it to the other injectors which shoot a very strong positive squirt of fuel while #4 doesn’t really do much at all. It gives fuel but just not much pressure and low volume of fuel compared to the others. Please help, is it a plunger that is only going part way down or what?
Thanks

 

[Janicholson]

Got a MD that has sat for 20 plus yrs. Got gas side working and cleaned diesel side up as far as filters and cleaned tank. I am a mechanic myself just not too familiar with injection pumps. So I first unhooked throttle and checked rack. Throttle moves free about 3 inches and has some spring resistance at the end, which I think is the governor spring compressing inside.
All was good so I ran it on gas, bled the filters and switched er over and took right off perfectly. But it has a miss on number 4. Inconsistent miss so I added about a gallon of transmission fluid to 5 gal of diesel and have ran it for about 3 hrs. Misses always at wide open and intermittent at slightly above idle. What I found is that by cracking bleeder it is only shooting fuel about every other time it should be and it doesn’t seem to have much pressure at bleeder. Removed the injection line right at pump and started it up and still, about every other or every 4th time it should shoot fuel it squirts a little bit out. I know this by comparing it to the other injectors which shoot a very strong positive squirt of fuel while #4 doesn’t really do much at all. It gives fuel but just not much pressure and low volume of fuel compared to the others. Please help, is it a plunger that is only going part way down or what?
Thanks

IIRC the individual injectors all get the same hit of pressure from the pump. the valving under each line connection distributes the fuel. S I would run it under load for a few hours and see if it gets better or seems to warrant longer running to cure it. Dieseltech (a wise and courageous member) will likely chime in. Jim

 

[grandad1066]

Thanks for the reply. Ya it’s like something inside that distributes the fuel across all 4 delivery valves is just not right. 4 is just weak and not much fuel while other 3 are good

 

[Janicholson]

Thanks for the reply. Ya it’s like something inside that distributes the fuel across all 4 delivery valves is just not right. 4 is just weak and not much fuel while other 3 are good

They are pretty simple inside with the cover off, take a look Mine had a stuck rack and piston. Dieselman may be the answer. Jim

 

[n9lhm]

Does it have the Bosch pump, or the I-H pump? The Bosch pump has individual plungers and may have something hung up in that plunger. The I-H pump has one plunger and distributor valves. If the other three cylinders are OK then it about has to be a problem in the distributor block.

 

[Oldiron29]

Got a MD that has sat for 20 plus yrs. Got gas side working and cleaned diesel side up as far as filters and cleaned tank. I am a mechanic myself just not too familiar with injection pumps. So I first unhooked throttle and checked rack. Throttle moves free about 3 inches and has some spring resistance at the end, which I think is the governor spring compressing inside.
All was good so I ran it on gas, bled the filters and switched er over and took right off perfectly. But it has a miss on number 4. Inconsistent miss so I added about a gallon of transmission fluid to 5 gal of diesel and have ran it for about 3 hrs. Misses always at wide open and intermittent at slightly above idle. What I found is that by cracking bleeder it is only shooting fuel about every other time it should be and it doesn’t seem to have much pressure at bleeder. Removed the injection line right at pump and started it up and still, about every other or every 4th time it should shoot fuel it squirts a little bit out. I know this by comparing it to the other injectors which shoot a very strong positive squirt of fuel while #4 doesn’t really do much at all. It gives fuel but just not much pressure and low volume of fuel compared to the others. Please help, is it a plunger that is only going part way down or what?
Thanks

If it anything like the TD6 I had got running for my cousin. It had green globs of old fuel stuck in the pump and dist. block. Once I got it all cleaned out after some running it cleared up, I used 2 stroke oil Not ATF. Both should be good.

 

[grandad1066]

Does it have the Bosch pump, or the I-H pump? The Bosch pump has individual plungers and may have something hung up in that plunger. The I-H pump has one plunger and distributor valves. If the other three cylinders are OK then it about has to be a problem in the distributor block.

It has a big letter A on the side

 

[grandad1066]

Does it have the Bosch pump, or the I-H pump? The Bosch pump has individual plungers and may have something hung up in that plunger. The I-H pump has one plunger and distributor valves. If the other three cylinders are OK then it about has to be a problem in the distributor block.

 

[grandad1066]

When I rotate the pump I can feel all the lifters move slightly and seem to rotate like they should. The distribution block I can move the pin on it as well with some pressure. As can see in pics they are a little pitted and not shiny like the others. That is the cyl that is not getting fuel correctly. How does the distribution block come apart so I can get in at the plunger and check it out??? Thanks for the help so far guys

 

[grandad1066]

Made a tool to remove the hex bushing deal on bottom of distribution block. Also removed the delivery deal on other side. But how does the rest come out and which direction??? Thanks

 

[grandad1066]

Does it have the Bosch pump, or the I-H pump? The Bosch pump has individual plungers and may have something hung up in that plunger. The I-H pump has one plunger and distributor valves. If the other three cylinders are OK then it about has to be a problem in the distributor block.

Loaded pics of the inside of pump. Got nozzle out of block and hex on bottom out. How do I get the rest out though?? It was dirty under the delivery tube

 

[n9lhm]

I have the service manual on that pump, I'll try to find it and scan some pages about the distributor block.