L4600 fuel injection problem

[WayneD]

Fuel valve got turned off by brush while bush hogging, it appears, same as running out of fuel. Turned fuel shut off back on and bowl filled immediately. We didn't know about the bleeder valve on top of the pump until later when talking to a local dealer. After turning the fuel back on, a friend tried to loosen front line on the top of the pump and turned whole assembly slightly he says. I didn't see him do it but line has been twisted slightly also it appears. The local dealer said he was told to NEVER try to bleed there on the pump but too late for us .................. He said the thinks that is how the fuel flow is adjusted. If so, how do I adjust it" Tractor now running but limps/stumbles on acceleration and has reduced power. Idles at about 750 - 800 with noticeable exhaust noise.

Many thanks in advance

 

[whitetiger]

You can not bleed the fuel system at the pump, it has to be bled at the injector to remove the air.
By trying to loosen the injection line at the delivery valve it is critical that a backup wrench be installed on the delivery valve so its position is not disturbed as turning the valve changes the fuel delivery. You will now have to remove the pump and send it to a reputable injection pump service center to be recalibrated on a pump test stand or replace it with a new pump.

Usually due to the cost of shipping, cost of repair, and long wait times, we install a new pump.

You stated that the injection line appears to be twisted, if it is it needs to be replaced also. An injection line that is twisted or bent will tend to start flaking inside and will stick the injector. If the injector sticks open, it will wash down that cylinder wall, scoring it and the piston.

 

[WayneD]

You can not bleed the fuel system at the pump, it has to be bled at the injector to remove the air.
By trying to loosen the injection line at the delivery valve it is critical that a backup wrench be installed on the delivery valve so its position is not disturbed as turning the valve changes the fuel delivery. You will now have to remove the pump and send it to a reputable injection pump service center to be recalibrated on a pump test stand or replace it with a new pump.

Usually due to the cost of shipping, cost of repair, and long wait times, we install a new pump.

You stated that the injection line appears to be twisted, if it is it needs to be replaced also. An injection line that is twisted or bent will tend to start flaking inside and will stick the injector. If the injector sticks open, it will wash down that cylinder wall, scoring it and the piston.

Could you be a little more specific? I'm trying to get my head wrapped around the Kubota style pump and how this would affect adjustment............................ . This all happened when a friend tried to "help" by cracking a line he could easily get to to see if injection pump was pumping. I know to bleed at the injector and not the pump.................. and so does he actually. He wrenched it with the clamp in place but the line was tight enuff the whole unit spun slightly. I guess that's a single line pump? I loosened the clamp, checked the unit beside it and it was snug........... didn't move it. The first one I snugged back down with just a few pounds torque, maybe 1/3 turn. Bled line and all is fairly well but doesn't sound quite the same as I remember. So I'm not working it hard till I get this resolved. So, you are saying I just need to unbolt this from the block and send it off for calibration. I'm just south of Atlanta, where might you suggest I go for this? Local dealer says he's never had this problem before and doesnt know where to go.

Thanks much

 

[kubotafreak]

Think of a barrel piston being cut like a helical staircase. The fuel control lever moves a Rack" that rotates all these helical cut fuel pistons inside the pump below the delivery valve. You twisted a delivery valve and changed that cylinders volume of pumped fuel per rack movement compared to the others. Under the rack is a cam with lifters of sorts that pump these helical cut pistons up and down. You might try to tighten that one back down the amount you think he spun it counter clockwise when trying to remove the line. Use the paint as reference if you can. They are sensitive adjustments. I never remove them even when freeing stuck injector pumps.

Whitetiger is absolutely right about kinked fuel lines. These lines do not have to be as tight as you think. They have tapered ball connections much like hydraulic jic lines. They only need to be tight enough to not leak.

If I'm not mistaken a counter turn on the delivery valve will increase the fuel. So that cylinder is more than likely getting too much fuel.

 

[whitetiger]

Could you be a little more specific? I'm trying to get my head wrapped around the Kubota style pump and how this would affect adjustment............................ . This all happened when a friend tried to "help" by cracking a line he could easily get to to see if injection pump was pumping. I know to bleed at the injector and not the pump.................. and so does he actually. He wrenched it with the clamp in place but the line was tight enuff the whole unit spun slightly. I guess that's a single line pump? I loosened the clamp, checked the unit beside it and it was snug........... didn't move it. The first one I snugged back down with just a few pounds torque, maybe 1/3 turn. Bled line and all is fairly well but doesn't sound quite the same as I remember. So I'm not working it hard till I get this resolved. So, you are saying I just need to unbolt this from the block and send it off for calibration. I'm just south of Atlanta, where might you suggest I go for this? Local dealer says he's never had this problem before and doesnt know where to go.

Thanks much

Oregon Fuel Injection: 541-485-1434
They do a lot of this style of injection pumps and have a great reputation.

I am surprised your dealer has not run into this, I see it a dozen or more times a year. Of course, most of our customers are from Missouri.... .