I searched the forum and I'm sure this is answered somewhere but I can't find it. We have a newer (2006 I think) 120C excavator that was run out of fuel today. I filled it up, pumped what I think is the priming lever and it fired right up for about 5 seconds and shut off again. I tried pumping and restarting several times but it will not fire up. It was at operating temperature but the lever I'm pumping doesn't seem to be doing anything. The filter is full of fuel and I opened up the plastic screw on top of the filter housing that I think is the bleeder but nothing ever comes out. Is there a step I'm missing in there somewhere? If anyone has any advice I'd like to try to get it going before it's freezing cold tomorrow morning. Thank you!
The lift pump that you are pumping on pumps off of a lobe. In some places on the lobe the little lever is not pushing down on the diapham. Open the plastic bleeder screw on the top of the filter housing. Bump the engine over just a little until you feel a springing action when pumping the lever. Pump that until you get a good stream out of the bleeder and then close. Then I pump about 20 more times. To speed up the process of starting you at this point can open up a couple injector lines and turn over on the engine. I usually do about 10 seconds. At this point you can tighten the lines back down and it should fire back up. JJ
Would the lever still move up and down if it was on the high side of the lobe? If it does that's probably what happened because the first time it seemed to work like I expected but after that it seemed to do nothing.
First of all, how often do you drain the water and dregs from bottom of fuel tank. If not often, it's not unusual when you run a machine out of fuel that the last little bit of fuel that had it running sucks up water and junk from bottom of tank and fouls up the fuel supply to engine. The parts pages show the Deere 120C has a cam operated diaphragm lift pump, has a manual lever on the side of the pump. If it's not moving any fuel when you operate manual priming lever it could be pump arm is on high lobe of cam, need to bump engine over a bit so pump lever go to low spot on cam, then manual lever will operate lift pump. I'd remove the secondary fuel filter, the one after the lift pump, and place a small drain pan under filter housing. Operate manual priming lever of lift pump and see if it's pump clean fuel into drain pan. If it does, reinstall secondary filter, pump lever until it has pressure, try cranking engine. May have to repeat pumping operation a couple of times. On Edit: Looks like Hardline beat me to it.
Yes it will still move up and down. It just will feel like it is not hooked to anything inside. When you bump the engine over it will then allow the pump to be manually primed again. JJ
Here's the update. I bumped the engine a few times and the manual lever does move some fuel. Once it fills up the filter though it just comes out of the plastic breather looking cap on top of the filter housing. It doesn't seem to build any pressure. I cracked open one of the injector lines and cranked the engine over a bit then tightened it up and it did start but only ran for about 10 seconds and shut off again. Once it shut back down I took off that breather cap thing and the filter was almost empty again. Could it be a pump issue? I've only had this machine for about 4 days and it's ran flawless until today. By the way, I'm not 100% sure it ran out of fuel. It had about 1/8th of a tank but it was operating on an incline when it shut down so I'm just assuming the fuel was on the wrong end of the tank and it sucked air when it shut down.
When you say breather cap do you mean the large screw on top of the filter housing? Probably about 2.5 inches in diameter? If it is leaking fuel out there then it has loosened off. There is a o ring in there that seals that cap. Check the condition of the o ring and reassemble.
Also did you you drain any water or debris out of the bottom of the filter ?
Could it have sucked some dirt from the bottom of the tank into a line somewhere between the tank and the primary filter ..? If so try blowing the lines out in reverse direction with compressed air.
After messing around with this for quite a while I blew out the lines with air, pumped it back up and ran it all day like a champ! It must have been blocked somewhere but it is no longer. Thank you sooo much!
And the moral of this story is ......... drain your fuel tank of water and sediment daily just like the Operators' Manual advises ......... Glad you got your machine up & running by the way.