Gday guys, I went to start my loader the other day and all it would do was turn over but would not fire, I cracked the bleed screw on the fuel filter and proceeded to prime the fuel pump. There was air in the system so I then bleed the rest of the fuel system ie, fuel pump, injector lines and then she fired up no problems. The loader runs no problems under load but now I have found that when it sits for a couple of days without being started I have to bleed the fuel system. Is there a solution for checking for leaks in the fuel lines to the tank, does the fuel system stay pressurised when the motor is turned off? Cheers Gus
Well, since nobody else waded in... You don't say if your machine is a -1 or newer, but I would start at the fuel tank and work to the injection pump. Fuel tank should have a vent line or a vented cap, has to be open or you get vacuum in the tank. This should in theory stall the machine when it's working, but you never know. Remove the cap and pull the fuel line off before the water separator or prefilter. Blow carefully a little compressed air back down the line to make sure it's not plugged with debris. Check all metal lines and hoses for signs of cracking or rubbing. Make sure the water separator is clean and can be blown through (again, low pressure air no more than maybe 5 psi). Install fresh fuel filters if you haven't already. The fuel transfer pump can suck air if it's mechanical, and the priming pump the same. That's about it. My first guess would be the transfer pump and/or the primer pump, bad check valve or just a bad seal on the suction side so it lets air in, but not fuel out. Good luck.
Yep its a wa 380- 1 Lantraxco, I have noticed when I pump the primer pump iam getting fuel by passing the plunger of the primer however it it is still priming the system. Breather isn't blocked checked that.Can not see any sign of wear in the metal and rubber fuel lines. Strang that it runs fine when primed up but when left over night requires priming next day.
have you checked the lift pump screen?.. should be one in the banjo bolt on the inlet side, pays to clean them on a service anyway the checkvalve from the injection pump may be bypassing over time and dropping the transfer pump pressure overtime, when you pump the primer pump you should hear it open up after afew pumps an drain back to tank, best to check it, it will be a banjo bolt similar to the others with a plug on the head of the hex, it'd not uncommon for people to remove the smaller hex plug to bleed the fuel system and loose the spring and/or the ball from the seat causing it to be low on transfer pump pressure and hard starting.. the spring does also loose the will to extend over time and does need replacement, any decent fuel injection joint will be able to supply one dont bother with Komatsu parts not sure if you have a fuel/water seperator? a seal may be bad in that causing the fuel to drain back over time also.. it doesn't take much at all to let the fuel drain back hope it helps.. Adrian
that'll be your problem right there.
Thanks guys for your responses I will check out the checkvalve and lift pump screen, up until a couple of days ago it was running fine, fired up first time every time so hoping its nothing major. ps what am I looking for with the check valve wear?
If you're getting fuel past the primer pump plunger, there's a good chance it will suck air going the other way. Maybe not enough to be a problem when it's running, but when it's shut down gravity will pull the fuel back down into the tank through one line or the other and it pulls air into the system. Again just a guess, but I would try replacing the primer pump along with the checks suggested by rare ss
i had a primer pump go bad on a JD and it let the system bleed down letting air in. the diaphragm inside the primer pump was leaking, it only took removing 2 bolts and 2 lines and put it back together.
photos Have attached photos of primer pump and check valve, the oring around the base of the primer looks abit suss and on the check valve it looks pitted so have ordered new oring and chec If that doesnt fix the problem I will move onto the primer pump as eric has suggested, start off at thk valves with new springs.e cheaper replacement parts and work your way up.
LOL, the term I would use for that is "knackered"
theres A problem, hopefully it's causing the issue
Okay replaced check valves and have primed fuel up to the filters and the injector pump, have noticed that there is no fuel bypassing the primer plunger any more and there seems to be good pressure when primed. However now iam not getting any fuel up to the injectors:Banghead
Currently as it stand when i crank the motor over iam getting a small amount of fuel coming from a couple of the injectors and nothing from the others,is there any other areas on the pump that need to be bleed before the injectors?
well, i still don't know what series you're working on, but then I'm not all that familiar with Kommie anyway. If it has the inline injector pump with all six injector lines connected in a row, there's usually a bleeder plug on the side of the body just below where the injector lines attach. Probably near the end where it mounts to the gear housing. Good luck
You sure there's good pressure when it's primed? odd that the fuel is NOT bypassing the primer plunger anymore, how did that fix itself? (unless I'm misunderstanding, or the new check valve isn't holding pressure)
There will be a check valve on the return side of the injection pump that is meant to maintain a small amount of pressure to the pump and prevent pump from draining. it will likely be in a banjo fitting on the backside of the pump.
Yer I have got good pressure when i prime the plunger,but i carnt explain why iam not getting bypass on the plunger itself any more not that iam complaining.I was talking to a mechanic about it the other day and he was telling there may be a bleed screw at the very top of the injector pump which will assist in priming the injectors. Currently iam away so will check it out when i get back, however i have been told they are a pain to bleed the air out.
Will check that one out to cutting edge, is that on the line from your injectors back to the tank.
yeh, it'll be the return line back to the tank the banjo bolt should have a plug on the head of the banjo with a spring and ball bearing seat sounds as though this is bypassing causing the loss off transfer pump pressure and/or having the fuel drain back overnight, you should be able to hear this banjo bypass when you pump the primer pump after about three pump it should make a small noise to drain once the pressure builds (and also feel it it as you pump) if you cant feel or hear the pressure build up it may be faulty.. like a mentioned it's not uncommon for people to bleed the system from the plug causing the spring and/or ball to be lost which makes it useless, also I've seen this banjo fitted in differant spots on the fuel system, inlet on fuel pumps, outlet on lift pumps all sorts of weriod spots have you found the screen yet?
I have taken some photos of the priming pump and bleed screw on injector pump, I primed up the fuel system again, but still nothing to the injectors when motor is turned over. There doesn't seem to much pressure on the plunger when primed. I followed the return line from tank to the injectors but there doesn't seem have the banjo bolt your talking about rare ss unless I am looking in the wrong area. I am starting to think it might be the new check valves I replaced as they were different in colour and also had double springs on them instead of one spring like the old ones. No haven't found the screen your talking about is that in the tank?
Heres a photo of the return line to the tank and a photo of the banjo bolt on the inlet side of the primer pump.
Found the screen rare ss its been doing its job.
By "doing its job" I take it was clogged? Hows the pressure now? IF you still cant get fuel to the injectors..Remove the long cap on the drive end of the injection pump, that will expose the control rack..Push/pull on it..does it move? IF NOT the rack is stuck..Remove the side cover 2, 10mm bolts and inspect.
screen wasn't to bad, I have taken the fuel line off from the tank to the pump and the pump check valve doesn't appear to be leaking fuel back to the line, can hear a slight sucking noise coming from the pump so took off fuel line to first fuel filter and when I loosened the hose clamp, abit of air escaped from the line. After I removed the line from from the pump to the first fuel filter the second check valves seems to be holding as there is fuel holding in the outlet banjo bolt.
bum steer just noticed fuel is running back to tank even with new check valves.
After you stop the engine? How are you seeing that, the pickup should be well down into the fuel? Not to restate the obvious, but if the fuel is draining back, there's gotta be an air leak on the suction side of the pump, between there and the tank then. Put about three pounds of air in the tank, watch for the sprinkler. Brute force approach. Rubber hose with a pinhole, steel line rubbed through on something, filter gasket, etc. She's fightin' ya, but keep at it, you'll win. :Banghead:bash
arnt the check valves supposed to stop the fuel draining back even if there was a hole in the fuel line from the tank to the pump? I have the outlet fuel line side of the pump off then I prime the pump up with the primer but as soon as I stop pumping the fuel trails back into the pump.:Banghead
Check valves hold the fuel upstream from the valves from draining back, if they're working properly. If there's any way for air to enter the system on the tank side of the first check valve, the fuel will still drain back to tank, but the engine should start on the fuel in the system, all things being equal, and then may or may not pull enough fuel to purge the air and keep running, or air lock and quit. Did you find the return line check ball valve that Cutting edge and Rare ss mentioned? I think at this point I would buy and install a new primer pump just because of past experiences with them, then work from there through the rest of the system.
Have brought new primer pump no more bypass on plunger, have noticed the check valves have a notch on them was wondering if that is a direction of flow indicator? haven't found that check ball valve on the return line, there is a banjo fitting going into the injector pump from the second filter which I haven't had a look at yet. will put up photo shortly to explain.
Have worked out why I haven't been able to get fuel to the injectors, when I got my boy to turn key on I noticed the fuel shut off lever did not disengage. I disengaged the fuel shut off lever and hey what ya know she fired up. I checked fuse for shut off lever and it hasn't blown so will check relay. Funny when you try and resolve one problem another one pops up.
Gus, don't worry about fuel going back the return line, it's to bleed air out of the pump. Make sure the return line is clear. Later Bob
Just and update, have fixed the broken wire to the fuel shutoff on injection pump which was why i wasnt getting any fuel to the injectors, and since I replaced the check valves and primer pump I have had no issues with having to bleed the fuel system when it has been sitting for a couple days, cheers for the advice guys.
Glad to hear you got it sorted, well done. :beerchug