Stalling under load

[BSAA65LB]

You have been finding crud in your fuel system. Until you are absolutely certain the fuel system is clean and correct, concentrate your efforts on the fuel system.

Generally when the complaint of sudden loss of power at the engine comes up, the hydraulic system gets blamed. Unless something has abruptly failed or someone has tampered with the hydraulic system, it usually is not the hydraulics.

Run a function that uses some horsepower but doesn't require near peak horsepower. Stick extend would be a good test. If the engine drags down extending the stick only, chances are it is engine.

And to go back to the first paragraph, you have found crud in the fuel. Get ready to spend some quality time getting your fuel system spotless again.

 

[JVS Equip]

Changed all the hydraulic filters today and the hyd oil (4200hrs). The only function draging the engine down is the stick. Let say i try scraping the ground or pushing a heavy boulder away from the machine, that would drag the engine down. When i say thats the only function, no other operation labours the engine, I could lift, slew, track, anything except extending or retracting the stick with a load.

 

[Hendrik]

Changed all the hydraulic filters today and the hyd oil (4200hrs). The only function draging the engine down is the stick. Let say i try scraping the ground or pushing a heavy boulder away from the machine, that would drag the engine down. When i say thats the only function, no other operation labours the engine, I could lift, slew, track, anything except extending or retracting the stick with a load.

So you're saying that if you curl the bucket in the ground or lift the machine with the boom it's fine but the dipper arm hyd ram loads the engine?

 

[JVS Equip]

I spoke to a dealer on friday, he guided me into the onboard diagnostic, machine is showing no codes. He then asked me to test a few functions.

Curl the bucket in the air and hold the controls, engine is fine.

Extend the stick to the limit and hold the controls, engine dies after a few seconds but actually extending it isn't a problem. Same with the boom.

Dealer said it may be a number of things, but i would need an est to check it.


So the machine can track, swing and lift (actually load a truck) without trouble. I can use the boom and stick to lift the machine off the ground and pretty high too.

 

[thebaz]

Does the machine track straight? Could be one pump is not de-stroking so it only stalls on the stick and not the bucket??? Sound a tough one, may need an expert to check it out on the actual machine.
Keep us posted.
Baz

 

[JVS Equip]

Machine tracks straight. This CX210 is european spec equipped with safety valves on the boom and dipper, one for each cylinder, three in total. Now these are the only functions affected. The relief valves are on the safety valves. Pressure has to flow through these to the cylinders and back.
From what I understand these are safety mechanisms for lifting which prevents the boom or dipper from dropping in the event of a burst hose.

 

[thebaz]

I am only guessing here, but if one of those valves were faulty that circuit would be slow or stall, but as you can move the bucket to it's limit and the motor doesn't stall, there is no reason why the motor would stall when basically you are creating that same condition with the arm. It could still be a computer related thing as it sounds like the pump/pumps are not de-stroking.
You can usually stall your tracks/arm/bucket or whatever on an excavator without the motor stalling so I keep thinking it is more likely to be pump controllers.
There may be an arm re-generation circuit that re-directs the lift return oil
to the arm for greater speed.
It would seem the problem is becoming more difficult to diagnose.

 

[tool_king]

JVS Equip
The screen in bango fitting will stop the dirt from clogging the rest of the system.But I would make sure the fuel tank was spotless clean.But the water serarator could collect some of the dirt.What did the dealer mean when he said you would need an est to check it.What is a est?

 

[JVS Equip]

Electronic service tool, unfortunately my local dealer does not have the correct one. I have actually removed the tank and had it cleaned.

 

[JVS Equip]

Overlooked Symptom

Pumps seem fine, ran the machine and turned on the computer to watch the pressure, according to what i explained to the person who was guiding me the pumps are good.

Now that sympton that i overlooked, everytime the machine stalls, i check the secondary fuel filter and its half empty, significant or not?

 

[TheCASEguy]

These CX210's and CX240 are nightmares on this phanton de-rating of the engine and dying out problems. Good call on the small screen in the banjo fitting. We usually just throw that out when they come in. I have seen some welding slag left over in the tank. This was causing blockage of the fuel line periodically. When the Excavator moved around, the blockage would also move and let the fuel out of the tank and then mysteriously block the line again. We fought that problem for two years on a customers CX210. This slag was about the size of a silver dollar.
The high pressure injection pump are not like the old pumps that most of us are use to. They cannot handle and water, trash or starvation. They go bad almost instantly. Usually a bad pump will throw up a 364 code (I think) its 36something.
There is a fuel pump relay that is located in the engine compartment. This is the most inexpensive component to check first.
And last but not least, my latest fix was a injection pump wiring harness. I had a broken wire in this. It was a special shielded wire for the circuit board. After replacing two bad injection pumps, we found this wire was sending a bad signal to the inj. pump circuit board (square black box on top of the VP44 Inj. Pump) and frying the pump. We replaced the harness installed a third pump and its working like new again.
On a side note. the CX "B" series have been outstanding and they have changed all that injection pump circuits. So far there is no problems at all and they have been out since late 2007.

 

[JVS Equip]

For some reason its showing no codes but i'll check again. A little more specific about that fuel pump relay? You seem to have experience with these, how would one know about the bad harness?

 

[TheCASEguy]

Realisticly for a shop, it is cheaper to just replace this item than charge $100.00 an hour to diagnose a relay. So I always just change this out (part #441777A1) . We found this harness problem by disconnecting each end of the harness and testing each wire individually with the wiring schematic. Its a lengthy process but we were out of options. We originally just repaired the sheilded wire. This was a mistake! If you find that a harness is needed, it might be too late for the pump. I have a place in Ca. that will check your pump, it costs me about $150.00. Not sure where you are at inrelationship to Woodland, ca. but they are a Certified Bosch VP44 Injection pump testing facility. There is only two (that I know of)that are certified for testing this pump. 530-668-1042
Also, go to this website. www.casepower.com in there you can look up parts. Also use this as a guide to where the components are located.
hopefully this helps

 

[JVS Equip]

For clarification the pump is not a VP44 more visually comparable to a P7100 although i would have to check it for a model number or something.

 

[willie59]

Now that sympton that i overlooked, everytime the machine stalls, i check the secondary fuel filter and its half empty, significant or not?

I'm gonna step out on the limb and say, yes it is.

 

[TheCASEguy]

Sorry for the VP44 confusion. I just looked at the pump we replaced and its a Bosch P80082-1.

 

[JVS Equip]

Restricted the return line (Just to test it) and getting better results with the performance. I've been advised to check for air leaks and entertain the possibilty of a new lift pump or check valve from the injection pump.

THECASEguy please correct me on that because i'm not sure if the check valve is in the return line or the injection pump itself. Remember this is no cummins engine, its an ISUZU.

 

[JVS Equip]

There are three check valves in the fuel system, two in the lift pump and one (comprises ball and spring) controlling the return fuel and pump pressure on the injection pump. Apparently "someone" who shall remain nameless unscrewed the one on the injectiong pump to bleed air out of the system the ball and spring went flying unknown to anyone. So we opened it and found none allowing the fuel to return to the tank faster than it should, not allowing enough pressure to build (Open to correction). Replaced it and voila!

This puzzled me though as i had a similar problem with a dt466 which would not start at all until we replaced the check valve at the end of the rail. The machine on the other hand started, tracked, swung and dug light but would stall under a load.

 

[TheCASEguy]

Sorry for not getting back to you. I just got back from the "N" series backhoe school. Sounds like its fixed though.

 

[thebaz]

Good find, you could have chased that one for ages. Shame "someone" kept silent about the flying spring.
Must be a good feeling to know it is fixed.