No fuel flow

[vffarm]

I'm having a problem with the fuel system on my M6800. It has about 1,100 hours. Air keeps getting into the system. This seems to be the by-product of it sucking fuel as indicated by the pump above the fuel filter sucking down tight. Air comes in and out of the settling bulb filter. When I replaced the filter I noticed that it was but half full of fuel. The new filter was filled prior to being installed.
After talking to my dealer, I've flushed the tanks and all lines. I replaced a small line, apx 1/8, which comes out of the pump mechanism and goes to a T located behind the filter. It was crimped.
I've loosened the injector couplings to allow air to escape, all per the video instructions of orange tractor talks.
The service manual has been no help.
I've ordered a new fuel pump, the low volume one located the on the side of the engine.
I'm truly at my wits end! Dealer or qualified mechanics can't get to it for week to two weeks. We use it to bale hay and our alfalfa is staring to bloom! Help!

 

[Bulldog]

Have you checked the vent lines?
It should have one on either side of the tractor. My 9000 has them hooked to the frame work that supports the rear of the hood. Dirt dobbers are bad to plug them up.
Is your fuel gauge working properly?
On mine that is the first sign that the vent lines are plugged. It all but stops the fuel transfer between tanks.
If the vent lines are clean I would check the fuel line that comes from the tank to the primary filter. It could be plugged or even coming apart on the inside.

I would look at all the simple stuff before starting to spend money on it.

 

[North Idaho Wolfman]

Agree with bulldog, check all vent lines. and the check valve by the filter too.

 

[vffarm]

huge help, I hope! I will be able to run down the vent lines and the check valves tomorrow or the following day, darn day job. How can I determine whether the check valves are good? many thanks to both, at least now I have a direction

 

[Tx Jim]

Simple way to determine if tractor has a plugged fuel tank vent is at fault is remove fuel cap and cover neck with a shop towel to determine if engine will operate correctly. I once owned a M4900 that acted as if it was out of fuel and would get air(vacuum) in water seperator bowl. Local Kubota dealer service manager told me to check small white screen in water separator fuel cutoff valve for plugging. Sure enough screen was nearly plugged solid. I removed screen and tractor ran fine until I traded i for a M7040

 

[Rockin R]

How do you check the fuel vent lines?

I had trouble with my M6800 losing power under load. I changed the fuel filter and cleaned the water/fuel separator. I saw lots of trash so I drained the fuel tanks. I bled the system like always but it won't run or it loses power. When it starts up, the water/fuel separator gets a big air bubble or void in it. Seems like the fuel flow is impeded before it gets to the filter or something. No amount of pushing on the pumper makes it run right.

 

[ironpony]

for a few bucks you can replace the rubber lines, fuel lines will collapse internally and have no signs of a problem on the outside. the will also flow fine with no suction, the suction is what collapses them.

 

[North Idaho Wolfman]

I would check and make sure you get flow from the feed of the tanks, as a plugged vent will not normally cause a no start condition.

And make double sure on the filter and water separator seals as a leak on one of those will also cause it to suck air.

 

[Rockin R]

What is the procedure for checking flow from the feed of the tanks?

 

[Bulldog]

How do you check the fuel vent lines?

May not be the right way but this is my way. Obviously look in the lines first to see if it has trash. If it's clean wipe the end off and give it a little blow. If it's clean air will pass thru very easy. If no air passes it's plugged and you need to clean it out.

I had trouble with my M6800 losing power under load. I changed the fuel filter and cleaned the water/fuel separator. I saw lots of trash so I drained the fuel tanks. I bled the system like always but it won't run or it loses power. When it starts up, the water/fuel separator gets a big air bubble or void in it. Seems like the fuel flow is impeded before it gets to the filter or something. No amount of pushing on the pumper makes it run right.

When you start it does it run good then get the air bubble or does it run bad from the start?

 

[Tx Jim]

What is the procedure for checking flow from the feed of the tanks?

Remove line from fuel tank and observe if "pencil size stream of fuel" flows out of open fitting.

Did you ever check screen in water separator cut-off valve for plugging????

 

[Rockin R]

It was running good, then got the air bubble. Yesterday it ran but badly (no smoke). Then (and currently) it won't even start, it does turn over nicely, however.

 

[Rockin R]

No, not sure we'd be able to see well enough to check it because the front loader is still on and in the way, and now it won't start so we can remove it.

 

[Bulldog]

When you pump it up does fuel go in the water separator or does it feel tight and hard to push?

 

[Rockin R]

It won't even start at all now.