I have been experiencing intermittent fuel system failure since running my July acquired D6N. Have done the following; Drained Refilled Tank Inspected Fuel Lines Inspected pressure regulator - looks ok - seems just like a new one. Replaced primary filter four times Replaced secondary filter twice Replaced short rubber fuel line that showed minor kink with brass elbow When this occurs, I get power loss, flashing "!" warning and audible alarm followed by engine stall if I don't power down in a few minuets. This sporadic failure seems to occur after I have been "pitching" the machine. Examble : After teetering atop several dirt mounds, compacting them in preparation for coming rain, I was not surprised by the cascade of power loss, warnings and engine shutdown. These failures seems to self correct after sitting overnight. With the last failure, I left engine running high RPM and reached arm into fuel tank to check fuel pickup for external debris block. None found. Felt no suction. Warm fuel seemed to be gently floating from pipe. Once pulled the secondary filter "near HUEI pump" just after failure. when filter drain valves were open, encountered a vacuum, air sucked into the system. After removing filter I remember the filter not being full and the little fuel I encountered was warm to hot. Any Ideas - much appreciated. Thinking I might call for Cat Field Technician.
Maybe the fuel tank isn't venting properly. I'm not sure if that machine has a dedicated vent or if the Cat corporate fuel cap is the vent. Might explain why the symptoms go away after it sits over night.
This, or some azzhat dropped a rag in the tank and it's sucking up into the pickup.
As always a S/N might help. It would allow one to look at the system in detail to know if there was a vent in the cap and other things.
Right on, Lantraxco, “This, or some azzhat dropped a rag in the tank and it's sucking up into the pickup.” I got my butt kicked by a KW W900 log truck with a Detroit 8v92. Many years ago starting out in the biz. Ran great 99% of the time, except occasionally pulling hard on long inclines. Rag in the saddle tank. The rigging crew would soak rags with diesel on cold mornings to help thaw out the frozen air valves on the yarder. Dip the rag, light it on fire and place the burning mess on the suspected frozen valve. A rag got left behind in the saddle tank.
Thanks, A "floater" in the tank would give the symptoms. The last time it acted up, I stuck my arm in the tank and felt the pickup for a block. I did not feel anything. Not even suction pressure at the inlet tube. At the inlet tube, I could feel warm fuel gently coming out of the pickup tube. I am trying to figure out what could cause this. One of the times it acted up, I changed the primary filter located just before the pump. When I opened the drain valves to drain the filter, the system sucked air. So the system was in a vacuum . I am going to guess, the means the HUEI pump is sucking hard on the pump side of the filter. Somehow. I think I remember the filter and the fuel being hot. I wonder if the filter drain system valves could be leaking? But why would this issue seem to occur after I have pitched the machine while dozing dirt piles ? Cat came out and charged me a ton to tell me they could not figure out the issue all pressures good. Not happy with that.
Have you removed the fuel pressure regulator and checked it for crap in it ? Or crap in the fuel line between it and the tank.
I removed the fuel regulator from the back of the head. Had a look at it. It seemed just like a new one. I can not remember if I checked the return line for flow. I know I used the hand pump and circulated fuel through the return. The fuel seemed to return fine. What would the symptom be if the return line obstructed between the tank and the regulator? The regulator is simply a device that opens when the pressure reaches a certain level. Right? if the return clogged what would take place? Would the pump know? Thanks
I don't know much about it. But if it is malfunctioning I would think you would have no fuel pressure at times or all the time. The fact that the IP is pulling a vacuum when you opened those drains is a definite indication there is a problem in the fuel tank or lines. Next time it acts up loosen the fuel tank cap and see if the vacuum is going all the way back to the tank. I would be tempted to drain the fuel tank and put a bore-scope in it and look carefully everywhere for something moving around in it. It could be something very small like a piece of gravel (little bitty rock).
Have you tried opening the drain valve in the bottom of the tank to see what comes out..?
Not a bad Idea to check again. I will let ya know . If i see anything.