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Cat 279D fuel problems?

bennyaus · 2022-11-01 19:55

On the day i had someone coming out to potentially buy my machine i was running around doing some things and suddenly rpm drops and stalls. Start it up, starts in low RPM and stalls. I thought maybe a clogged filter, i pulled them both off, cleaned them, reinstalled, turned to ignition and they filled. Still no solution. Any suggestions as to what may be the culprit here? I tried to upload a video but it didnt work.

Replies29
  1. #1heymccall2022-11-01 20:49

    Updated below.

  2. #2bennyaus2022-11-01 21:00

    Thanks for the reply, here is the additional info. 3200 hours

  3. #3heymccall2022-11-01 21:12

    Could the strainer on the lift pump be restricted?

  4. #4bennyaus2022-11-01 21:16

    Am I correct that the strainer is first, then the pump, then into the other bigger filter? If so, after removing both filters and replacing them, when put the key to ignition, both filters filled quickly with fuel, so I would think that's not clogged, it may be further down the line?

  5. #5heymccall2022-11-01 21:20

    You may very well have an engine/ fuel injection or even electrical problem. It's just that EVERY skidsteer and CTL here has had debris restrictions in the supply circuit. Yours is new enough that an inlet screen was added by Caterpillsr at production time. Mine (all but one) are older and have since had an inlet screen added. Do you have the advanced display where fault codes can be retrieved?

  6. #6bennyaus2022-11-01 21:37

    All of the following are logged events, not active at the time. E459-2 engine rated horsepower output changed engine power rating mismatch. E570-2 Unexpected right motor forward speed detected check the motor speed sensor and wiring E875-2 Low system voltage check the battery and alternator 523602-0 Aftertreatment regeneration frequency high-most severe

  7. #7bennyaus2022-11-01 21:45

    All of the following are logged events, not active at the time. E459-2 engine rated horsepower output changed engine power rating mismatch. E570-2 Unexpected right motor forward speed detected check the motor speed sensor and wiring E875-2 Low system voltage check the battery and alternator 523602-0 Aftertreatment regeneration frequency high-most severe

  8. #8bennyaus2022-11-01 22:52

    Another thought I had is from memory whe. I first opened the back up after this happened, the large fuel filter was not full, and I don't think it got full until I pulled both off and cleaned them. If there was a blocked filter, meaning fuel stopped going to the engine, do I have to bleed the lines of air? Prime it in some way other than just leaving it im ignition for 30seconds?

  9. #9Nige2022-11-02 07:47

    First comment. You can't upload videos direct. Upload it to YouTube and link it seems to work best. I would strongly suggest that you disassemble and clean the screen in the pump as HMC suggested before proceeding further. If it does nothing else it will at least eliminate the possibility of a partial blockage. That could be the kicker. Try this thread. You may need an electrical schematic in which case that will require the Serial Number. HeavyEquipmentForums

  10. #10bennyaus2022-11-02 08:06

    Good point, here is link to the video

  11. #11bennyaus2022-11-02 08:11

    If the filter/screen being talked about is one if these circled, I have cleaned those. If not where would that be. The filter on the left when this first happened was only about 1/4full. After cleaning they immediately filled. I will look into that thread but won't be able to look into it until I am home with the machine. That code wasn't showing as an active code at the time. Gtl04439 is serial.

  12. #12Vetech632022-11-02 08:11

    Cleaning them doesn't work unless it's a screen. Once water gets into the paper of the filter it acts like a plug. I just dealt with this problem on a paving machine yesterday.

  13. #13bennyaus2022-11-02 08:15
  14. #14Nige2022-11-02 09:01

    It's the smaller of the two you circled. That one you can clean or replace, Part Number 416-5884. The larger element should not be cleaned, only replaced. Part Number 363-5819. There are also two O-Rings on it that come separately, 4L-7711 & 483-6423.

  15. #15bennyaus2022-11-02 19:22

    I am trying to understand the fuel system. Can someone please explain where I am wrong, I have a rough drawn photo for reference. Fuel goes from main tank to small particle filter, through priming pump and to the water separator/filter. From this point I'm unsure of flow. There are 2 lines that go from there to a secondary tank, what is the flow here, one goes to the bottom, one tees off the top to the fuel injector pump? There is also another line from the secondary tank to fuel injector pump? What is the flow of this? Then there is another line that goes from the back of the secondary tank to main tank, is this an overflow back to main tank? It's not easy to get a photo of what I am calling the fuel injector pump, but this is the best I have. Is there an imv valve that's there that I would have to check, is there a good photo of this so I could know what I'm looking at.

  16. #16heymccall2022-11-02 19:46

    Third line goes through relief valve (preventing filter overpressure) and back to tank. 345-3516 is the part number. Valve assy- relief

  17. #17heymccall2022-11-02 19:58

    This is all I could find.

  18. #18bennyaus2022-11-02 21:33

    So in this picture full pressure fuel would be coming out on 5, 9 is a pressure valve, and then on 4 it would be out to the high pressure pump. All other hoses are some sort of overflow or relief, is that correct?

  19. #19Nige2022-11-03 06:19

    Be careful referring to #9, that is a hose clip and it appears everywhere. From HMC's illustration above....... The filter has two connections on the side and one on the top. The inlet and outlet are on the side and should be marked with arrows (circled) indicating direction of flow. Fuel comes from the tank to the transfer pump via hose #21C, then from the pump to the filter via hose #21B and an inlet elbow connection on the filter housing. The outlet connection (a straight fitting) feeds fuel to the HP fuel pump via hose #5, 1-2psi check valve #1, & hose #4. The purpose of the check valve is to prevent the HP fuel pump from being directly exposed to transfer pump pressure. The connection on top of the filter has a relief valve (highlighted) to prevent over pressure and provides a return to tank line for fuel via hose #21A.

  20. #20Nige2022-11-03 07:38

    Just a thought. Is the "secondary tank" that you refer to actually part of the main fuel tank.? The fuel tank is U-shaped as seen in the illustration below. It has hose connections on both sides and my guess is that the hose #22 is actually a balance/breather hose connected from the top of one side of the tank to the top of the other side. It will be there to maintain an equal fuel level in both "legs" of the tank when the tank is full. Hose #21 on HMC's drawing above will also be a return to tank, probably from either the HP fuel pump or from the injector fuel rail.

  21. #21Nige2022-11-04 06:16

    This is a stitched together view of the return lines around the HP fuel pump and the fuel rail. The return line starts from the relief valve at the end of the fuel rail #10 via the tube #9. That tube connects to the hose #21 and returns to tank via that hose and tube #2. There are also connections into tube #9 from the cylinder head at Location F and a banjo fitting on the side of the HP fuel pump at #18. So a total of 3 locations feed into one return line at this point.

  22. #22bennyaus2022-11-05 17:54

    Thanks guys for all of the input, I have managed to confirm fuel to the high pressure pump, but not any further(it may be getting past it, I just haven't tested). Nige thanks for the clarification on the tank, that makes sense that it is one larger tank. I believe I am past my skills at this point, so I will be getting someone to take a look at it. But I am curious, would you expect when removing the return from the top of the filter as shown In the photo that it should be under pressure? And I also found a plug from the wiring harness, does this have a place to go, or is it just unused from a standard harness?

  23. #23Nige2022-11-05 18:10

    Did you find it under pressure.? Try removing the fuel tank cap and check for pressure at the same location again. Can you see a number on that orange wire, maybe 976.? It looks as though it could be the Arc Suppressor for the Ride Control.

  24. #24bennyaus2022-11-05 18:15

    That would make sense on the wire, it seems to be plugged into something As for the pressure yes, when I removed the hose it was under pressure, gas cap off no pressure

  25. #25Nige2022-11-05 18:38

    Look for a Part Number on the Arc Suppressor for confirmation. Should be 189-3158. That makes no sense. I'm certain the tank cap should be vented. If it was not then how does air get into the tank as fuel is used.? Try running the machine with the cap cracked and see what happens. Looking at your original symptoms an air lock caused by a blocked fuel cap could potentially explain them. Often the caps are serviceable and the filter element can be replaced. Doesn't seem to be the case for this particular cap though - P/N 304-3885.

  26. #26bennyaus2022-11-05 19:07

    I tried to run it with fuel cap off and no luck, if there was some sort of air lock, where would be the best place to try open up the system to flush the air out?

  27. #27Nige2022-11-06 04:26

    That is a common rail fuel system and will bleed itself of any entrained air provideid that enough fuel is being supplied to the HP pump. I think this is where you are up to now. Replace the large fuel filter and go from there.

  28. #28Chabig2023-06-20 19:12

    Any update on this

  29. #29subdural2024-10-01 19:35

    thank you for the info in this post, ive found it helpful in how the system is all set up.