I would like help to figure out a fuel problem

Discussion in 'Heavy Equipment & Pavement' started by SLSNursery, Dec 23, 2000.

  1. SLSNursery

    SLSNursery LawnSite Senior Member
    Messages: 442

    I have a 97 Case 580 SL backhoe with a diesel engine. The machine typically starts on the first click, everytime. Since it is stored inside, the only exception to this is when we leave it outside in the cold, which is to be expected. Friday morning, I needed the machine to start loading some sand, so I hopped in (it had been parked inside) and turned the key. The engine turned over fine, but I surmised that there was no fuel getting to the injectors. I opened the primer screw on the fuel line after the fuel pump, and air came out. Next, I pulled off the fuel/water separator. It was almost empty. I made sure the fuel line from the tank was clear, put a new in-line filter on, a new separator, then primed it. Still nothing. Then, I opened up the injectors until diesel flowed, bingo, the machine started right up and worked fine for the rest of the day.

    Any ideas what might have caused this. I am afraid that because we won't be open for a few days it will become airbound again. Is this the sign of a bad fuel pump??

    Any advice would be helpful. Nothing is worse than counting on a machine to start and finding out it won't when you need it.
  2. thelawnguy

    thelawnguy LawnSite Silver Member
    Messages: 2,411

    ". I made sure the fuel line from the tank was clear"

    How did you do this? By blowing back into the tank? My first thought would be a plugged fuel pickup screen inside the tank. (the coarse brass screen to keep birds and bones out of the fuel system ;) )This may be why you got fuel after checking out the system. Also check for a defective check valve, there should be one somewhere in the fuel system. Possibly its integral with the fuel lift pump.
  3. SLSNursery

    SLSNursery LawnSite Senior Member
    Messages: 442

    I did blow back into the tank, and also checked visually to see the sludge factor. Since the machine continued to run fine after clearing the line and changing the filters, I have no reason to believe the problem is at the tank. I will be able to drain any unseen garbage out of the tank without a problem when I get a chance next week.

    The check valve idea sounds like it is on the right track, however, I'm not sure I saw one on the line. If there is one, my bet is that its on top of the fuel pump, and probably integral with the pump. Hopefully someone has the same machine and has some experience.

  4. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    you might have a dried out fuel line line or return line,if it lets air in it will lose its prime overnight,you'll have to prime it every day until you fix it.
  5. sam c

    sam c LawnSite Member
    Messages: 55

    i have to agree with the check valve answer, i have an f350 6.9 diesel that when ever the fuel in the tank gets below the return line acts the same way. but it will start after alot of cranking. call your local case dealer they should be able to help.
  6. 9FT.PILES

    9FT.PILES Banned
    Messages: 62

  7. CHC

    CHC LawnSite Member
    Messages: 65

    Any chance that there might have been ice in the line or filter?
  8. SLSNursery

    SLSNursery LawnSite Senior Member
    Messages: 442

    There didn't seem to be a dirt problem in the tank, but I have to assume it was a problem with dirt clogging the in-line fuel filter. I will probably change the fuel lines this winter when we get a break, just to be safe, because they are starting to look a little dry-rotted, but since the incident it has been fine, and running strong.

    It was not ice, because it is stored indoors, and had not been out for very long, in not very cold weather.
  9. Lewis Haynes

    Lewis Haynes LawnSite Member
    Messages: 1

    If you haven't found the problem with the hard starting machine... Answer some questions, does it skip, studder and slowly come up to full engine speed with excessive white smoke then run fine after a few minuites???
    If so check all fittings on the fuel system and make sure the filters are tight..
    find the return line from the cyl. head to the fuel tank. Put a clear plastic line on it and make a loop in the line, elevate it above the fuel tank and let it sit for a few minuites after you shut the engine off and look for bubbles in the line traveling back to the head if so then the problem is in the return side ... if they go to the tank then the fuel pump or the injecter cups are possibly bad.. Good luck..

  10. Alan

    Alan Member
    Messages: 1,185

    It might pay to keep a close watch on your engine oil level. Watch for it to go UP! Probably a real long shot but as I recall the primary pump on that rig is a mechanical fuel pump mounted on the block and driven off the camshaft. Might be a cracked diaphragm letting it inhale air on the intake stroke. If that is the case it could also be pumping diesel into the crankcase. As far as check valves go there are two of them in the fuel pump just to make it pump. Should not be possible to get any return flow through there unless something is bad.

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