Hi All, I am currently troubleshooting a hard start problem. Machine details: Model: D5KXL S/N: WWW01440 Hrs: 4329Hrs. Engine: C4.4 common rail system There are no active faults. When engine is cranked no smoke coming out of exhaust. I checked fuel intake from low pressure lines to fuel rail pump - fuel is present. But there is no fuel coming out of the fuel rail pump to the common rail. With cat ET I have carried out pump solenoid valve test- ok. Solenoid seemed to be working fine. I also did injector solenoid test -ok. All solenoids ok. I also noticed that even though there is no fuel in the common rail, the fuel rail sensor is giving an unsteady reading of 140kpa - 630kpa. This reading is given when machine is just on key on position (not running). I have already ordered a new fuel rail sensor and still on its way. Apart from this any recommendations or checks I can carry out while waiting for the sensor. Thank you in advance.
Not really. It's a C4.4 so my experience would be the following sequence of replacements to address the low rail pressure. Obviously you try the cheapest solution first. 1. Rail pressure relief valve. 2. Injectors. 3. HP fuel pump. I hate to tell you this but usually you end up doing all three because 1 & 2 don't give the desired results.
Thank you very much for reaching to me. I will definitely keep that in mind. Cheers
Are you talking of a "crank - no start" condition or an extended cranking time before the engine finally fires.? Is it worse when the engine is hot or cold.?
It is a crank no start problem. Cannot fire up.
I think you are into the three possibilities that I mentioned before. I just hope it’s the cheapest one.
I have a question. If there is no fuel fuel present in the common rail or the high pressure fuel lines, and the fuel rail pressure sensor is indicating a false pressure reading to the engine ECM, is there a possibility that the engine ECM will not open/energize the high pressure fuel solenoid valve on the pump to allow fuel to the common rail? Because upon cranking there is enough fuel pressure from the transfer pump to the fuel rail pump but no fuel is coming out from the output of the fuel rail pump. Like I said I did the fuel pump solenoid valve test and it checked okay. The solenoid valve is controlled by a PWM signal from the engine ECM.
The issue here is that if the sensor was not giving a false reading then the pressure generated in the HP side of the fuel system would be even less and therefore less probability of the ECM giving the required signal to start the engine.
There are three possible reasons for that.......... See points 1, 2, & 3 in Post #2 above. It will be one or more of those.
I really appreciate your advise and assistance. I will provide feedback on repairs done. Thank you.
I'm sorry I can't suggest anything more but my experience of C4.4 engines has been universally negative. I put it down to a combination of poor fuel filtration design and/or poor maintenance. The result of the foregoing is premature internal wear of components in the fuel injection system.
Just to add to Niges comments check to see that the pump is rotating. The pump drive gear is a taper fit to pump shaft (no key) and has been known to slip
Noted. Thank you
As a follow-up for the record I did a bit of checking on this. Apparently it was potentially a problem with the engines in machines from first built up to somewhere around Serial Number WWW880. The solution was to change the injection pump gear Part Number from 230-8989 to 425-7107 and at the same time the torque on the shaft nut was increased from 66 to 75 ft lbs. Thanks to @Mark250 for the lead.
Just a thought but if you have access to ET and can somehow electronically spoof the signal from the rail pressure sensor to the engine ECM to indicate an even higher pressure then you might be able to get the engine to start - provided the problem is not a loose FIP gear that is..... If you could get it started maybe diganostics could be somewhat simpler because you would be able to test various parameters with the engine running.
They also wont start without a cam sensor signal. Haven’t seen a spun gear yet but would put cam sensor out of position. (Possibly crank/cam error code?) Another thing to try is to disconnect the MPROP (solenoid on top of high pressure pump). This will default the pump to full flow. Should see an increase in ET of rail pressure sensor. Try spraying some ether in intake. If it will start on ether its injectors worn. To test the injectors you can do a leak off test to measure the leak off when cranking. Worn injectors will have excess flow and wont build pressure to crack open. Check the earth strap on ecm. Had bad earths cause a loss of trim files for some reason.