Hitachi EX 100-3 recent runnability issues

[carl oswald]

Our excavator started up the other day and had a very low, sluggish idle. This unit usually starts up great and responds very quickly to the controls. But regardless of what speed you wanted the idle to be, the excavator slowly gained engine RPM's as it warmed up. Then it seemed to be OK, responding well to the speed controls. BUT, it dogged out and died if you used anything hydraulic (swing motor, boom, bucket, thumb, tracks, etc). There is absolutely NO black sooty exhaust during any of these events. It seemed to me that this was a classic case of lack-of-fuel. We treat our fuel and do not feel it has anything to do with cold weather fuel gelling issues.
So we cleaned the banjo bolt strainer, changed the fuel filter, ensured the fuel line from the tank was in good shape, and tested for good fuel flow out of the fuel tank. There is no fuel / water separator on our unit. These moves did NOT resolve the problem. So we are looking for advice on our next steps.

Thanks guys.

 

[dieseldog5.9]

Some of those machines had multiple screens in the fuel system. I would probably setup a separate tank to gravity feed the engine,and see if that helps. I have seen everything from a tank full of Ice, tank full of gravel, dead mice in the inlet of the tank. Also make sure the fuel solenoid is fully moving.

 

[Tones]

The primer/lift pump has plastic valves which get pitted so it doesn't work so well. They cost about $6 plus freight for a kit and a very simple job to install.

 

[carl oswald]

The primer/lift pump has plastic valves which get pitted so it doesn't work so well. They cost about $6 plus freight for a kit and a very simple job to install.

Hi. Appreciate the feedback. Is it easier to replace the entire fuel pump for $60 or buy a rebuild kit? Also I cannot find a rebuild kit online....

thanks!

 

[Tones]

Hi. Appreciate the feedback. Is it easier to replace the entire fuel pump for $60 or buy a rebuild kit? Also I cannot find a rebuild kit online....

thanks!

Bosch parts are the same as Denso. Any good tractor or truck shop can order them in for you

 

[carl oswald]

Hi. Thank you all for your input on this issue. The problem ended up being a loose connection to the injector pump. This is very hard to see or touch, therefore difficult to recognize. So basically this loose linkage caused the engine to bog down with any hydraulic usage. Sounds like a super easy fix but so hard due to the difficulty in accessing this part of the engine compartment.