B7100D injection pump

[IdahoNative]

Absolutely zero fuel is discharging from the rear most two injection pump delivery valves. The forward-most valve just kinda bubbles out.

Is valve clearance related to the injection pump? Maybe I errored when I adjusted the valves. When an exhaust valve pushrod started to raise, I set the intake to 0.008". When the intake pushrod started to drop, I set the exhaust to 0.008".

On an injection pump 15381-51011, is injection timing set by the shims near the bottom of each delivery valve? Or does the pump body gasket/shim set the timing? The WSM doesn't say a lot about this. I want to retrace my steps to make sure I didn't alter the injection timing.

Before replying, please read about my recent history...

I previously posted about my B7100D suddenly seizing up. Prior to this, it started and ran good, but had excessive white smoke. The seizure was caused by a pressure plate finger snapping off and lodging itself between the "bell housing" and flywheel. While I had the tractor split, I removed the 750 engine. I cleaned the carbon from the valves, replaced the valve seals (no valve lapping needed), replaced the head gasket (and head shim...which it DID NOT have one on it), glow plugs, oil pan gasket, speed control gasket, and hydraulic pump gasket. I also replaced the o-rings and crush washer/gaskets in the injection pump delivery valves. I did not disassemble the injection pump body beyond this. I also removed and carefully cleaned the injectors and replaced the gaskets. I bled the injection pump at the inlet breather.

Obviously, I caused this new problem...since the system functioned before I started this journey. Any ideas as to where to look? If my valve clearance method is correct, should I punt and ship the injection pump for a re-build job?

Thanks, in advance.

 

[torch]

Timing may be an issue, but you should get fuel to the injectors even if the timing is off a bit. It can take quite a while to bleed all the air out, how long did you crank it?

 

[IdahoNative]

Timing may be an issue, but you should get fuel to the injectors even if the timing is off a bit. It can take quite a while to bleed all the air out, how long did you crank it?

Thank you for your reply.

I cranked it for a while, about 10-15 seconds several times over. Continued this after one delivery valve had some fuel bubbling out. Nothing ever flowed out of the other two delivery valves.

I removed the pump body this evening. I found the two dry delivery valve tappets were seized up into the body. I used PB Blaster and wiggled the bottom tappets for about 10 minutes each. They now move up and down. And I believe the control rack is supposed to slide front/back freely too. Mine is stuck, luckily exactly at the engine block notch-out.

My theory is the previous owner didn’t change fuel filters often. It was working when I purchased it. My fountain test yielded less than an inch of spray, so it wasn’t very efficient. I drained all fluids when the pressure plate exploded. That was a while ago and given the high humidity here in Florida, I think the injection pump internals started to “rust” together. I will soon find out after I free the control rack. Fingers crossed

 

[torch]

That was a while ago and given the high humidity here in Florida, I think the injection pump internals started to “rust” together.

Yeah, that could be an issue all right. <lol>

Good luck with it. I hope you can get things freed up without damage.

 

[IdahoNative]

Yeah, that could be an issue all right. <lol>

Good luck with it. I hope you can get things freed up without damage.

Well it’s definitely corroded inside the injection pump body, just enough to stick two delivery valves and the control rack. I got everything apart without damages and they are going into my sonic parts cleaner. Might need input on how to orient plungers/delivery valves vs the control rack position. But that will be a new thread…

 

[Kenonf]

If you youtube "d750 fuel" pump you will find a few videos on people reworking them...
I believe your tolerances will be/are shot and its time for other parts/fuel pump.
I have had luck getting Kubotas at the local auction yard and fixing my fleet.
PM me if you want to talk parts.
I did see a nice write up on this forum about fuel pumps, search d750 here too.

 

[Fedup]

No offense intended to anyone here, but there are reasons injection pump shops stay busy. Regardless of what one sees on U tube videos, then translates it into an "I can do that" sort of thing, injection pumps were not intended to be homeowner serviceable. Yes, there are certain aspects of pump repair that can be successfully done, and I guess I've done my share over the years, but there are also certain things I don't do. Taking this style pump apart and expecting to put it back together in running condition is one of the latter. For the $300 or so a pump shop will charge for that, it's far less than what it would cost to replace what I would mess up in the process.

Proper disassembly, cleaning, inspecting, assembling, calibrating, and all that, I leave to those equipped to do so, and the "know how" to do it. To those addicted to videos, and who use that as a substitute for knowledge and experience, I say "go for it". You might get lucky. Then again, you might end up paying someone else to do after all, and buying a lot parts you didn't need to begin with.

 

[IdahoNative]

If you youtube "d750 fuel" pump you will find a few videos on people reworking them...
I believe your tolerances will be/are shot and its time for other parts/fuel pump.
I have had luck getting Kubotas at the local auction yard and fixing my fleet.
PM me if you want to talk parts.
I did see a nice write up on this forum about fuel pumps, search d750 here too.

Thank you for the reply. I found some great videos and the pump is working now. It wasn’t very difficult getting it to function.
And you’re correct about other parts needing attention. I ordered a few parts that should arrive this weekend . I will let you know if I need to talk parts.

 

[IdahoNative]

No offense intended to anyone here, but there are reasons injection pump shops stay busy. Regardless of what one sees on U tube videos, then translates it into an "I can do that" sort of thing, injection pumps were not intended to be homeowner serviceable. Yes, there are certain aspects of pump repair that can be successfully done, and I guess I've done my share over the years, but there are also certain things I don't do. Taking this style pump apart and expecting to put it back together in running condition is one of the latter. For the $300 or so a pump shop will charge for that, it's far less than what it would cost to replace what I would mess up in the process.

Proper disassembly, cleaning, inspecting, assembling, calibrating, and all that, I leave to those equipped to do so, and the "know how" to do it. To those addicted to videos, and who use that as a substitute for knowledge and experience, I say "go for it". You might get lucky. Then again, you might end up paying someone else to do after all, and buying a lot parts you didn't need to begin with.

Thank you for your reply and no offense taken.

Every situation and the decision to DIY or let the pros handle it is different. In this case, I have the time, the tractor isn’t used for income purposes and having it function immediately isn’t necessary. I spoke to my local shop. They would rebuild the pump, untouched by me, for about $850. If I disassembled, cleaned and put the pieces into ziplock baggies, the wanted…… $850. In this case, minimal risk with a great reward. Did I get lucky? Maybe, but real research and being extremely methodical probably helped a little.

As far as replacing parts unnecessarily, I think everything on this tractor will soon need replaced . The guy I bought it from doesn’t know what “ maintenance” means or he just didn’t care.

 

[Fedup]

$850? You must be talking to the wrong people. You should be able to have leaks stopped on that pump for less than $350 if that's all that's wrong.

 

[IdahoNative]

$850? You must be talking to the wrong people. You should be able to have leaks stopped on that pump for less than $350 if that's all that's wrong.

$850 is for a rebuild with calibration, kinda worst case $$. I stopped the leaking by cleaning the parts in my ultrasonic cleaner and installing new gaskets and o rings. It fountains better now too. Before disassembly, each valve would discharge less than an inch high, now they squirt about 5 inches. If I need it calibrated, it’s not gonna cost too much now.