Hello, I could use some help diagnosing my excavators issue. I have a 1996 EX120-5 (serial# 1E4P053428) that has a bogging problem when the hydraulics are worked hard or multiple hydraulic control inputs at once. Originally thinking it was a fueling issue as it would die at idle and would require hand priming before it would restart, I drained and rinsed out the fuel tank, blew out the supply lines and fittings, replaced the rubber supply line to the water separator with new, cleaned the banjo filter at the water separator inlet (it was clean), cleaned the banjo filter at the inlet of the feed pump(it was nasty but not completely plugged), I stalled a new fuel filter and drained the water separator. Also verified that the fuel cap is venting properly. it runs better now that the banjo filter is clean and now it will idle forever without dying. It will still bog the engine down when operating the hydraulics. when it bogs, there is no black smoke, and recovers the revs quickly after stopping the control inputs. HP or E mode selections seem to make no difference at all in the performance. now I am thinking I may have a hydraulic issue? Or should I keep chasing a fuel problem? thanks in advance for any help I can get. - A.J.
How is your air filter? At full gas what are your or how many RPMs, does your maschine have under a load, they should be around 1790 +/- 100. Anything under your motor is being drugged down from your pump, not sure about that model, but you should be able to adjust your regular on your pump.
My air filters are brand new. Sorry, I didn’t mention that in my original post. And as far as the Rpms go, I only have a dial for throttle position selection in the cab. The machine does not have a tachometer. The auto idle does work and seems to come up to full idle, but not sure exactly since there is no tach. could there be a hydraulic issue causing these Bogging symptoms? The symptoms exist at all stages of heat cycle/ engine temp. I have heard about an angle sensor issue in these machines but I am not familiar with that part myself. thank you for the reply! I’ll keep messing with it
no smoke, keep chasing a fuel problem until proven otherwise. What's the history of the machine? and the problem? Any rubber fuel lines are suspect. The water separator is extremely suspect. check for cracks/leaks or replace/bypass. Why was the transfer pump inlet plugged and not the water separator and inlet? you could do a fuel supply pressure check, or check the fuel return for air bubbles.
Thanks delmer. The history of this machine is unknown. I bought it in this condition last week (the only way that a guy like me can afford one is to get it broken) and brought it to my house a few days ago. Since then I have been digging into the fuel system. I believe I have confirmed the entire low pressure system ASIDE from bypassing the separator. I did blow it out and it looked fine but I’m still a little surprised that it’s a plastic part in a fuel application. I believe the banjo filter in the separator inlet was clean while the one in the lift pump inlet was dirty was because the previous owner was aware of the on in the separator inlet and unaware of the other. He did just a couple basic troubleshooting efforts before I bought it. could there be an issue with the injection pump or any part of the high pressure side of the fuel system causing these symptoms? Like some sort of relief valve that could be wore out or maybe stuck open? Or am I on the wrong thinking path? if I do a fuel pressure check, what pressure should I be seeing if all is well? thanks again for the reply’s.
Welcome to HEF ajewing ! How about a picture of your instrument panel and of your injection pump (or a picture of your plates on top of the engine). From the monitor picture I might be able to tell you how to get into the monitor to check codes and engine rpm's. Also knowing what injection system you have I might be able to figure out your fuel pressure spec as well. If you are running a HPCR fuel system you might be able to see the low pressure fuel system fuel pressure in the monitor as well.
Well I did some more troubleshooting. I put a chunk of clear hose inline on the return to the fuel tank and saw a few air bubbles returning to the tank. I bypassed the water separator and that helped out with the air bubbles flowing through the return line, but did not solve the bogging/stalling issue. After that I filled the fuel tank to the brim (Since I know the tank is now clean and the supply line is new) just incase the hydrostatic pressure Could help... turned out it didn’t help. I have checked the banjo screens several times throughout this project and have seen no junk in them since I cleaned out the fuel tank. unfortunately, I have double, triple checked that there is NO black smoke when the engine bogs/stalls. But I feel pretty good about the fuel system being adequate unless my feed pump or injection pump is getting weak. I have not checked the fuel pressure with a gauge yet but I did buy one today to install when I get time. do you guys think I am on the right track Still thinking it’s a fuel issue after my troubleshooting results?
Mg2631, Here is a photo of my instrument panel. I did not see any plates on the engine. Thanks for all the help guys.
And here is a picture of my injection pump and a picture of the data tag on my feed pump.
Unfortunately the monitor is older than I expected. No accessing codes with that one (or any other information). An inline pump like that could have fuel pressures anywhere from 10 - 30 psi. I don't have any specs for those, but I bet Lachau could supply that.
The lift/prime pump could also be worn and very easy and cheap to repair. They have plastic plungers in them that if the surfaces get pitted they won't pump much. The kit costs about 6 bucks plus postage. PS they are a Denso pump but Bosh parts fit as well
Great. Thanks for the help I’ll get a rebuild kit ordered. You don’t by chance know what part number it would be do you? I can dig around but I figured I’d ask. 105220-6250 is the number on the data tag of my feed pump.
No idea of part numbers sorry. The engine make and serial number should be sufficient. The pump serial number is best. Hope it works for you.
Did the lift/prime pump rebuild cure your problem? I've got a ex160lc-5 with very similar problems.