so I have this 450DLC in my fleet with 9800 hours on the clock with isusu 6w1g tier 3 power. code 1239.01 or p1094 for isusu, came on book says no pump pressure stage one. I started with changing fuel filters, blew back feed and return lines, checked strainer in the banjo bolt on transfer pump, drained fuel tank and pulled down the sump to check for debris, found nothing and code still active. next I tapped in fuel pressure gauge onto transfer pump, 30psi at idle, 45 at ft, started digging and after an hour the fuel pressure starts dropping got down to 32psi then I pinched the return line and pressure stays the same, code comes on, ok so I change the fuel supply pump, which comes with the transfer pump, and overflow check valves on pump and secondary fuel filters. put it back into service and two weeks later the code returns, this time fuel pressure is good no drop at all, replaced common rail pressure sensor out of desperation with no change. my next step is to try and see actual and desired rail pressure but I don't have access to the software, any thoughts?, did I miss something?
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John Deere 450DLC excavator fuel issue
- Thread starter cpe667
- Start date
Hey mate
There is another 2 overflow valves on the secondary fuel filter housing they do go faulty a bit and cause the issue your describing.
Also if there is to much leak off from the injectors it will cause a similar issue I have the return flow specs at the office and can get them for you on Monday if needed
There is another 2 overflow valves on the secondary fuel filter housing they do go faulty a bit and cause the issue your describing.
Also if there is to much leak off from the injectors it will cause a similar issue I have the return flow specs at the office and can get them for you on Monday if needed
tool_king
Senior Member
cpe667
What company do you work up in CT ? I will if I have any thing on this machine .
What company do you work up in CT ? I will if I have any thing on this machine .
The return flow from the 6 injectors should be less than .440ML per minute if you just remove the steel tube on the side of the head and measure the flow from there. But I thinks its best to remove the rocker cover and then remove the leak off line joining the 6 injectors and start and run the machine you will loose a bit of fuel into the engine but you should get no more than a dribble (approx70ML)from any injector if its flowing out you have a issue with that injector.
The best way to check the operation of the pressure limiter is to remove the fuel return tube from the limiter valve and cap the tube with a bolt and nut using the copper washer from the banjo bolt then start and run the engine at high idle with the boom over relief no fuel should come out of the valve itself if it does it's faulty. spec is around 29000PSI but you can measure that anyway as the fuel pressure should never reach that pressure.
If you want to measure the fuel pressure you can back probe the rail pressure sensor using the signal wire (pin2) and the ground wire (pin3) If your getting around 4 volts with boom up over relief at high idle in H/P mode thats good and where it needs to be.
You can also use the common rail judge on the dash works ok too.
The best way to check the operation of the pressure limiter is to remove the fuel return tube from the limiter valve and cap the tube with a bolt and nut using the copper washer from the banjo bolt then start and run the engine at high idle with the boom over relief no fuel should come out of the valve itself if it does it's faulty. spec is around 29000PSI but you can measure that anyway as the fuel pressure should never reach that pressure.
If you want to measure the fuel pressure you can back probe the rail pressure sensor using the signal wire (pin2) and the ground wire (pin3) If your getting around 4 volts with boom up over relief at high idle in H/P mode thats good and where it needs to be.
You can also use the common rail judge on the dash works ok too.