Hitachi UH122

[etd66ss]

If what you are calling a canister has the dome nut on the top is a centrifugal oil cleaner and should be cleaned out at every service. The gunk inside has to be scrapped off.
Back to the lift pump, what you have circled is indeed the primer but it's also the lift pump and driven off the injector pump so it's a combination of both. On the inlet side is the famous or infamous screen in the banjo bolt which is also worth checking at this time. In the lift pump there's 2 nylon plungers that get pitted causing a loss of suction. European engines use this same set up. I've put a Denso kit into a Scania truck engine with a Bosh fuel system so I know they'll go the other way. A kit would cost about 20 bucks and about 1|2 an hour of your time.

PS the plunger has to be screwed down when not in use, leaving it lose will cause it to wear out.

OK, I figured that it needed to be threaded down when not manually pumping, been doing that.

What I find annoying with the parts manual I just bought is it does not have parts breakdowns for the HYD pumps or engine parts. I guess I am used to CAT manuals that have EVERY SINGLE PART that is on the machine. So do I have to find separate parts manuals for the Kawasaki pumps and valves, as well as the Isuzu engine?

I see where aftermarket pumps are available:



But I'd rather just find a rebuild kit etc.

 

[BC Placer gold]

Those primer/lift pumps are repairable with rebuild kits available either Denso or Bosh. A darn sight cheaper and easier than fitting another pump. I have also seen rubber suction fuel lines delambimate internally which has all the same symptoms as you have.

We replaced all the fuel lines on our Euclid C-6 dozer due to internal delamination. The machine got to the point where it would run 5-10 minutes before fuel starvation would cause the engine to die.

 

[Diesel Dave]

Very strange your parts book doesn’t show the hydraulic pump breakdown.
The Deere 790/792 parts page’s have the pump complete breakdown a bit further back.
Just for giggles, what’s the part number for the complete individual hydraulic pump ?

 

[etd66ss]

Very strange your parts book doesn’t show the hydraulic pump breakdown.
The Deere 790/792 parts page’s have the pump complete breakdown a bit further back.
Just for giggles, what’s the part number for the complete individual hydraulic pump ?

It seems anything that has its own serial number tag on it (engine, swing gearbox, pumps, valves, track motors, etc) are not broken down in the parts manual, they are just listed as a single line item. I believe this machine is pre Hitachi-Deere partnership, so going to be a nightmare to find parts as everything I'm sure is obsolete.

 

[Diesel Dave]

Ur right Hitachi generally has 3 parts books per machine.
- Engine (by engine model) ,
- “ Parts“
- “ Equipment component parts “ , which has all the breakdowns .

 

[etd66ss]

Some lift pump/primer pics:




Looking online this is the closest match I could find to a lift pump parts breakdown: 105237-1370

I assume item 5 (pump plunger) would be the culprit.



I was looking for an engine serial number nameplate, found a stamping. I assume the numbers after the E120 is the S/N?

 

[Tones]

That's it as per my last post. The banjo fitting with the rubber hose has a screen inside it. Check that it isn't blocked.

 

[etd66ss]

That's it as per my last post. The banjo fitting with the rubber hose has a screen inside it. Check that it isn't blocked.

I will check that. But if it were blocked doesn't that mean manual priming via the hand pump would not work, yet it does?

 

[Welder Dave]

The manual hand pump may have enough pressure to push a small amount of fuel through the obstructed screen. That would certainly explain why it would run for a short time only.

 

[etd66ss]

The manual hand pump may have enough pressure to push a small amount of fuel through the obstructed screen. That would certainly explain why it would run for a short time only.

Here's hoping it's just a clogged screen.

Both this machine and the Komatsu D65S have fuel delivery issues. I drained a bit out of both machines to check for water and sediment, but like many have said, maybe hose delamination.

 

[Tones]

Both will have pretty much the same fuel system.

 

[361brock]

Maybe it's time to check the tank your pumping from to fill your machines.

 

[etd66ss]

Maybe it's time to check the tank your pumping from to fill your machines.

I currently don't have my own tank, so been doing the 5 gallon jugs from a Mobile station etc. However, the majority of the fuel used to get both these machines running was fuel from the Hitachi. Very old, varnish smelling stuff. But neither machine had water. However the Komatsu D65S-6 did have a lot of black flaking material coming out of the tank drain, yet the metal screen leading to the float tank was not clogged, so dunno.

 

[Welder Dave]

Fresh fuel would be much better and help clean up the lines, especially if you added some diesel conditioner to it. I know you're not trying to spend too much but using who knows how old the fuel is, is just making things harder for yourself and contributing to more problems.

 

[etd66ss]

Fresh fuel would be much better and help clean up the lines, especially if you added some diesel conditioner to it. I know you're not trying to spend too much but using who knows how old the fuel is, is just making things harder for yourself and contributing to more problems.

I'll fix both machines up properly at some point. Just need to get one more moved to my property. Both of these machines are long term future projects. Don't really need them, but I have the sickness...

 

[skyking1]

You have the iron fever. Somehow I've managed to avoid it.

 

[Welder Dave]

Hopefully the sickness doesn't deplete your finances too much. The Hitachi is good machine if you can get it sorted out economically. It was one of the best excavators ever made.

 

[etd66ss]

Hopefully the sickness doesn't deplete your finances too much. The Hitachi is good machine if you can get it sorted out economically. It was one of the best excavators ever made.

All said and done, with what I have into them to get them functining well enough to load and unload, and what it cost to haul them, I am probably at about $5200 total for both, a little over half scrap value. If I get them working and make use of them someday great. If I don't and end up having to scrap them (don't want to), then so be it. These days I really only go for the very good deals, where ppl need machines gone off their property etc.

 

[etd66ss]

Well, certainly seems like the screen in the banjo fitting was the likely issue:







Cleaned up all the parts:




However, when I used the hand pump I could feel I was building more pressure and then the seals in the primer pump let go and it is dumping fuel.

Trying to talk with FridayParts for a rebuild kit but it seems they only have the entire pump. I suppose I could take the pump apart and see if I can measure up the seals, easy if it's all o-rings.

 

[Tones]

The screen can be unscrewed from the bolt for proper cleaning. It's the nylon plungers that may need replacing and should be available from a good fuel injection shop. They should stock the 0 rings and copper washers.