Sumitomo 145 stalling issue

[Tyler1991]

I have a 1997 sumitomo 145 excavator that suddenly has a hydraulic/fuel issue. It runs full rpm and as soon as you put a load to it will bog down and sometimes eventually stall/die. All functions make it stall under load (tracks, boom , thumb, etc).

Right away I thought it was a fuel issue but now I'm not so certain. Initially I replaced the primary fuel filter, replaced the water separator, rebuilt the feed /fuel pump , cleaned filter in banjo bolt, aired out fuel lines.

I'm trying to find the next troubleshooting step. Could it be a stuck hydraulic valve or solinoids on the relief? Is my next step pressure testing under load? Thanks.

 

[mikebramel]

Any smoke out the exhaust when it loads up

 

[Tyler1991]

A little but not too black.

 

[yanmar]

yes mine has the same problem but its on a site loading and seems to do it ok but totally no power. wheres the banjo bolt with the filter in it? is there only one on this machine?

 

[GaryHoff]

Banjo fitting screen is in the inlet fitting of the first fuel filter.

 

[yanmar]

Thanks

 

[Jamjamex]

Hey guys I caught your posts on sumitomo 145 stalling , I have one here in Scotland doing the same, pumps were rebuilt thinking we had worn insides dragging engine down. No luck but it still looks like hydraulics pulling engine down.
We have replaced a proportional valve which was faulty ( burnt out) and find now the new valve is getting no power to it. Machine works if you screw in the end of the valve or feed it with voltage direct although it is at full pump stroke and still stalling.
There must be a brain of some kind on this system to control the valve also sensors but we cannot get any info on this machine here in Scotland.
The guy we bought it from said it was imported from the states about 9 years ago.
Grateful for any help with this
Thanks