LS125 - ran out of fuel, now doesn't run properly

[Tom Brown]

... so I ran my LS125 out of fuel. Basically, I wasn't paying attention and I just ran it all day. The last 20, or so, seconds of operation involved the thing running low on power, surging, and then stalling. I checked the tank and it was empty. After adding 4 gallons of fuel, I got it running. It idles perfectly but when I throttle up, it will sink back down to idle speed. Should I try bleeding it again? I doubt I bled all the air out. The thing is, it idled fine for 20 minutes and still won't run properly.

 

[Tazza]

If you had it idling for that long surly the air would be out.
Just how did you prime it? on a Kubota there is a bleed screw you un-do then you MUST tighten it up or it will run then die, could it be something as simple as that?

 

[Tom Brown]

If you had it idling for that long surly the air would be out.
Just how did you prime it? on a Kubota there is a bleed screw you un-do then you MUST tighten it up or it will run then die, could it be something as simple as that?

Thank you, Tazza. When I bled it, I only bled one injector line. I've double checked it and it is tight. The unit will idle perfectly and smoothly. If I move the throttle to the WOT position, it will come up to operating RPM for a few seconds and then go back down to idle. I've inspected the throttle cable and it looks to be properly attached to the throttle body and I can see movement when I adjust the throttle. I'll give it a better look this evening when I get home from work.

 

[92LX555]

Thank you, Tazza. When I bled it, I only bled one injector line. I've double checked it and it is tight. The unit will idle perfectly and smoothly. If I move the throttle to the WOT position, it will come up to operating RPM for a few seconds and then go back down to idle. I've inspected the throttle cable and it looks to be properly attached to the throttle body and I can see movement when I adjust the throttle. I'll give it a better look this evening when I get home from work.

Probably not the issue but it is worth checking the fuel pump. I don't know where it is mounted on the 125 but I know on my 555 the fuel pump is at the bottom and has to work hard to pump the fuel. Mine idled all day long when it needed more fuel the pump could not keep up. Again, probably not the cause but it would only take 5 minutes to check.

 

[Tom Brown]

Probably not the issue but it is worth checking the fuel pump. I don't know where it is mounted on the 125 but I know on my 555 the fuel pump is at the bottom and has to work hard to pump the fuel. Mine idled all day long when it needed more fuel the pump could not keep up. Again, probably not the cause but it would only take 5 minutes to check.

Thank you. It does sound like a fuel pump. So far, I have checked the air cleaner (it's pretty much new), fuel filter (looks new... I can blow through it easily), and the fuel system for leaks. During the testing, I turned the stop cock off at the fuel tank and forgot to turn it back on before trying to start it. Realizing the issue, I turned it back on right away but now it doesn't even fire much. The machine still has the 5 fresh gallons of diesel I put in immediately after I first realized it was struggling for fuel. I'll try priming it again this evening but it looks like tomorrow I'll be ordering a new fuel pump. Times like this, I wish I had the service manual. Unfortunately, it won't be here for a couple of weeks.

 

[92LX555]

Thank you. It does sound like a fuel pump. So far, I have checked the air cleaner (it's pretty much new), fuel filter (looks new... I can blow through it easily), and the fuel system for leaks. During the testing, I turned the stop cock off at the fuel tank and forgot to turn it back on before trying to start it. Realizing the issue, I turned it back on right away but now it doesn't even fire much. The machine still has the 5 fresh gallons of diesel I put in immediately after I first realized it was struggling for fuel. I'll try priming it again this evening but it looks like tomorrow I'll be ordering a new fuel pump. Times like this, I wish I had the service manual. Unfortunately, it won't be here for a couple of weeks.

Again I am not familiar with the 125 as I have a 555 but I had a heck of a time with my fuel pump. On the 555 the fuel pump is basically attached to the frame and is in-line pump that is not submerged. With mine, as soon as you turn the key you can hear the pump working. First time it went I visited the local old Allis Chalmers dealer next door and just used a pump he had in the store. It worked for a day or two and then it stopped again. Priced a new one from New Holland it was somehere around $200...ouch. Took my chances that the failure was a result of the bladder getting dried out from sitting on the shelf for so long and the pump has ran for two years now. Not bad for $60. Other issues have prevented the machine from moving in 6 months. Before you spend big bucks I would check around your local dealers to see if they have anything that is comparible. I would also try M and N Sales in Wisconsin. They are a salvage yard that may have a machine that they are stripping that still has the fuel pump. 715-748-5325

 

[Tom Brown]

Again I am not familiar with the 125 as I have a 555 but I had a heck of a time with my fuel pump. On the 555 the fuel pump is basically attached to the frame and is in-line pump that is not submerged. With mine, as soon as you turn the key you can hear the pump working. First time it went I visited the local old Allis Chalmers dealer next door and just used a pump he had in the store. It worked for a day or two and then it stopped again. Priced a new one from New Holland it was somehere around $200...ouch. Took my chances that the failure was a result of the bladder getting dried out from sitting on the shelf for so long and the pump has ran for two years now. Not bad for $60. Other issues have prevented the machine from moving in 6 months. Before you spend big bucks I would check around your local dealers to see if they have anything that is comparible. I would also try M and N Sales in Wisconsin. They are a salvage yard that may have a machine that they are stripping that still has the fuel pump. 715-748-5325

Thanks for the help. I will give them a call. I went home at lunch to clean the air filter and check the fuel filter. Both look new. When I blew through the fuel filter, a mist of diesel came out the other side. It wasn't either of those things. Something new has happened, though. Now, when I turn the key to on, neither the "Timer" LED nor the "SOL" LED come on. Of course, the machine won't turn over. I have to switch it to service mode to get it to turn over. Is "Timer" the glow plug timer? I assume "SOL" means "Solenoid". As in... solenoid is energized and ready to drive the starter.

 

[Tom Brown]

Thanks for the help. I will give them a call. I went home at lunch to clean the air filter and check the fuel filter. Both look new. When I blew through the fuel filter, a mist of diesel came out the other side. It wasn't either of those things. Something new has happened, though. Now, when I turn the key to on, neither the "Timer" LED nor the "SOL" LED come on. Of course, the machine won't turn over. I have to switch it to service mode to get it to turn over. Is "Timer" the glow plug timer? I assume "SOL" means "Solenoid". As in... solenoid is energized and ready to drive the starter.

OK... the electrical issue was an improper operational sequence. The machine works fine when operated according to the manual. Now I'm back to the original issue. I'm going to replace the fuel filter before ordering a new pump.

 

[Tom Brown]

OK... the electrical issue was an improper operational sequence. The machine works fine when operated according to the manual. Now I'm back to the original issue. I'm going to replace the fuel filter before ordering a new pump.

I apologize for all the posts in this thread. Thanks again for the help so far. The current status is this: changed the fuel filter, and blew out the fuel hose between the filter and the input on the pump. Now I can open the stop cock on the fuel tank and the fuel will pour out the pump end of the hose. I estimate the flow at 1/4 cup per minute. The machine starts and idles nicely but will not stay at high RPM for more than a few moments. Just for laughs, I gave it full throttle and let it run at near idle speed while I put my hand over the open fuel filler and then poked the air nozzle between my fingers. With a little tank pressure, the engine revs right up to full RPM. Is that a clear sign of a bad fuel pump or could it stil be a restrictive filter? I haven't tried with no filter yet but I hesitate to do that.

 

[mllud]

I apologize for all the posts in this thread. Thanks again for the help so far. The current status is this: changed the fuel filter, and blew out the fuel hose between the filter and the input on the pump. Now I can open the stop cock on the fuel tank and the fuel will pour out the pump end of the hose. I estimate the flow at 1/4 cup per minute. The machine starts and idles nicely but will not stay at high RPM for more than a few moments. Just for laughs, I gave it full throttle and let it run at near idle speed while I put my hand over the open fuel filler and then poked the air nozzle between my fingers. With a little tank pressure, the engine revs right up to full RPM. Is that a clear sign of a bad fuel pump or could it stil be a restrictive filter? I haven't tried with no filter yet but I hesitate to do that.

When you ran out of fuel it could have sucked some junk from the bottom of the tank. I would suspect the filter. The pressure your adding wihh the air would force more fuel thru the filter.
I would be afraid to take the filter out . You could do that if you ran a hose to a container of fuel you knew was perfectly clean. As a test to see if its the filter or pump. Mike

 

[mllud]

When you ran out of fuel it could have sucked some junk from the bottom of the tank. I would suspect the filter. The pressure your adding wihh the air would force more fuel thru the filter.
I would be afraid to take the filter out . You could do that if you ran a hose to a container of fuel you knew was perfectly clean. As a test to see if its the filter or pump. Mike

Sorry tom ;I see you chainged the filter. It could be a weak pump. Also check the fuel pick up tube that runs down into the tank They can rot. get small holes that suck air.

 

[Tom Brown]

Sorry tom ;I see you chainged the filter. It could be a weak pump. Also check the fuel pick up tube that runs down into the tank They can rot. get small holes that suck air.

By swapping in a clear hose between filter to the inlet on the fuel pump, I was able to see what was happening on the suction side. The air wasn't bleeding out. I could watch an air bubble move toward the pump and kill the engine as soon as it got there. Basically, by studying it, I could tell I was going to need to bleed the system dozens of times. This is made easier by filling the tank right to the very top of the filler. From what I can tell, it's impossible to bleed the system when it's low on fuel because there isn't enough pressure to force the air out when the banjo is opened. I ended up bleeding, starting, bleeding, starting,..... dozens of times until it would run sufficiently well that I could run it at WOT around the neighborhood. It took quite a while but it eventually cleared itself and now seems to start better than when I bought it. Thanks again for the help. It is really appreciated.

 

[mllud]

By swapping in a clear hose between filter to the inlet on the fuel pump, I was able to see what was happening on the suction side. The air wasn't bleeding out. I could watch an air bubble move toward the pump and kill the engine as soon as it got there. Basically, by studying it, I could tell I was going to need to bleed the system dozens of times. This is made easier by filling the tank right to the very top of the filler. From what I can tell, it's impossible to bleed the system when it's low on fuel because there isn't enough pressure to force the air out when the banjo is opened. I ended up bleeding, starting, bleeding, starting,..... dozens of times until it would run sufficiently well that I could run it at WOT around the neighborhood. It took quite a while but it eventually cleared itself and now seems to start better than when I bought it. Thanks again for the help. It is really appreciated.

Tom
Thats the way it would act if the pick up tube inside the tank has either broke off at the and is short or has a hole and is sucking air. Once the pump grabs fuel and has a solid supply of fuel the air should be pushed right out. You could exoerience problems again when the fuel level drops below the level and again starts sucking air. When you filled the tank you filled above the level of the problem. I hope im wrong.
Im glad you got it going. The clear hose was a good idea to see what was going on. Mike