L4240 engine bogged now won't start

bullockcm · Jun 8, 2015

Tractor is a L4240 with 130 hours. All service has been done by me per the owners manual. Fuel is shared with another tractor that hasn't had any issues.

Was working with the tractor on Saturday, had been doing some dirt work for roughly an hour with the box blade then switched to the brush hog. Mowed for about 30 minutes and the engine bogged down, I lifted the mower up and bumped the throttle up a bit, engine picked back up and I assumed it was because the grass was a bit wet. The bogging happened 2 more times and I decided something wasn't right so I stopped and checked all the fluids, screens, and air filter. Everything looked fine so I tried going back to work, bog happened within a couple of minutes so I stopped again and checked the sediment bowl and fuel filter, both looked clean. Put the filter back in, bleed the fuel system per the manual, started the tractor and let it run for 30 seconds, stopped the engine and closed the air bleed valve on the fuel pump. Now the engine won't start at all.

Since then I have drained the fuel and replaced with known good, replaced the fuel filter and air filter. I have bleed the fuel system per the manual and cracked the rear fuel line at the injector and found fuel there. I have also verified the engine stop solenoid is working properly. Sometimes I get black soot from the exhaust when cranking the engine but sometimes there is nothing. Engine won't crank unless all the safeties are meet(pto, clutch, etc) so I don't think the problem is there.

Everything points to the engine not getting fuel, aka air in the lines. The forward 3 fuel lines on top of the engine appear to either take a special tool, some dis-assembly, or special knowledge to get at.

Anybody have any suggestions on bleeding the lines or other things to check?

boudreaux81 · Jun 9, 2015

Can you crack the lines at the injection pump? Be careful not to allow the delivery valves to turn when trying to looses nuts on lines. If there is no fuel coming at delivery valves check the mechanical stop on side pump. I know your tractor has electrical solenoid but make sure there is not a mechanical as well. Make sure arm is not to stop position. If it is not then you could try removing that cover on side injection pump. There are 2 springs. One that hooks to governor and the other to stop. Make sure the springs are connected and that the rails slide.

art · Jun 9, 2015

Thirty seconds to clear the air is not enough to run a tractor. You will need to get to the other injector lines at this time to finish bleeding the air!

Kubota 2007 · Jun 9, 2015

Are you showing any fault codes on the instrument panel? Engine could be in the protection mode, possible a bad sensor,etc.

R_Walter · Jun 10, 2015

I agree with the other poster who suggested air in the fuel lines.

Egon · Jun 11, 2015

Is there another small screen in the fuel delivery system?

what do you get at the injection pump bleed screw?

bullockcm · Jun 11, 2015

Bit of an update, first the tractor is back up and running, definitely was air in the fuel lines. I think there is some air still in them, I will get to that in a bit, because the tractor does not yet have full power.

While probably not impossible I think it would be slightly more difficult to attempt the line bleeding on your own, I didn't feel right asking my 8 month pregnant wife to help so I had the local dealership send someone out. Good idea since I didn't really know what I was doing anyway.

I had made sure the battery was fully charged but we still had to hookup jumper cables before we had the tractor running. Now to why there is probably still air in at least 2 of the fuel lines... It appears the L4240 and probably any of the 4 cylinder 40 series L tractors have the most limited access to fuel lines both at the injector and pump of all time. There is just an air bleed at the pump, no fuel bleed screws anywhere and no primer on the pump. The only injector line easy to get to is what I will call #4 which is the rear most one. The other 3 are down in the "valley" between the air intake manifold and the valve cover. I think I might be able to get to them with a crows foot but I don't own one yet, but I will soon since I plan on having the tractor for awhile it will be a good idea to figure out a way to get at line 1-3. We were able to get at the #1 and #4 lines at the pump but the spacing was so tight that there is no way to get on lines 2 & 3 without completely removing 1 and 4.

Answer to above questions for future reference:
-No error code on the intellipanel.
-No additional screens and no fuel bleed screws.
-Boudreaux, you mentioned a whole bunch of things I don't understand and wouldn't have any right messing with

at least not without a well written service manual.
-Art maybe on to something however with the exception of making sure the fuel tank was full I followed the owners manual in regards to the 30seconds of running with the fuel pump air bleed open after having removed the sediment bowl.

So here is what I have learned, whole thing was primarily from my inexperience with diesels in general. Change the fuel filter even if it looks fine, it cost roughly $4, I will be doing this annually from now on or more frequently if needed. When changing the fuel filter make sure the tank is full, bleed the sediment bowl when putting it back on, and finally per Art run the tractor for much more than 30 seconds, more like a few minutes.

I will be buying the service manual to see if a procedure already exists for bleeding the system, if not I will be trying to find a tool or combination of tools to access the lines at the injectors. Since I found no reference material online about L4240 fuel system bleeding and it seems a bit more difficult than the average system I will do a write up and or video if I am successful and maybe save the next guy a bit of grief.

I believe this is the first time I have thought maybe I didn't buy the right tractor... why would they make something so difficult to access that should be somewhat routine!

aeblank · Jun 11, 2015

I have an L3940. I certainly make it a point to NOT run out of fuel (famous last words, I know).
When I replaced my fuel filter, I didn't have much problem. I thought I was having a problem, but it was because I didn't re-open the fuel shut off. Duh. Also, I managed to break off the fuel bleeding knob, which I still don't know how it works. Bought a new one, but figured I'd not replace it till the next fuel filter change.

So anyway, bleah bleah bleah, I'm interested in your write-up when you do it. =)

wmonroe · Jun 11, 2015

I'm about to do the 400 hour service on my 5240 and have changed at least two fuel filters already. So far all I've done is to close the fuel valve, remove the sediment bowl and filter, replace with new filter, open fuel shutoff, let fill for 15-20 minutes while I grease the tractor or other things and start up and go. So far i haven't had any trouble but we'll see what happens in a couple weeks when I try again. Good to hear you're back running again.