Changed Kubota M6800 water separator, now won't start

[whis]

find the bleed screw on water separator and loosen it then put a little air pressure in fuel tank, it will fill it up

 

[sixdogs]

find the bleed screw on water separator and loosen it then put a little air pressure in fuel tank, it will fill it up

It's too soon for me but I have heard about that and that it works. How much pressure? And by bleed screw would that mean anything that would allow air to escape past the separator? Kubotas do not have a bled screw on the separator but rather a wheel you can turn that is on the fuel pump. Right now I'm waiting for the O ring that will be in on Monday and perhaps solve the problem.

 

[ronchp]

When you said pumping the bulb didn't do anything, could you tell any resistance on the bulb? I have seen a leaking diaphragm on those bulb type pumps once before that I had repair before the fuel system would fill. Do you have a shutoff valve in the line you could disconnect, put your hand over the hole and see if it is creating any suction?

 

[sixdogs]

When you said pumping the bulb didn't do anything, could you tell any resistance on the bulb? I have seen a leaking diaphragm on those bulb type pumps once before that I had repair before the fuel system would fill. Do you have a shutoff valve in the line you could disconnect, put your hand over the hole and see if it is creating any suction?

I have a shutoff but I damaged the O ring and can't get a new one until Monday. It's possible the diaphragm could be bad but the easy answer is the O ring needs to be replaced before I dig into anything else. When I removed the shutoff lever I did not notice and suction being created. I'm not too bothered by that right now because it was hard to get one hand on the pump and the other to cover the hole.

 

[whis]

the kubota's I have worked on had a phillips head screw on the filter head, anything to let the air out. just hold a rag over fuel tank and apply small amount of air pressure.

 

[TractorGuy]

I have to pressurize the tank on my backhoe to get it going after opening the system. I use a large rubber stopper with a small hole in the center and blow into it with a blow gun attached to an air tank for filling tires. Anything flat with a small hole in the center that will cover the fuel tank hole should allow enough pressure to bleed it out.

Any little air leak will stop it from running. I added a small engine filter on the line before my sediment bowl to catch debris before it gets into the system. I have to replace the short hose that comes with that filter every time I change it or it will suck enough air to shut me down.

 

[sixdogs]

OK, here's the answer. It was the fuel/water separator restricting the flow.

It was a struggle to figure out this simple answer but the water separator has a flow valve in it so you can turn the fuel flow on or off with a little lever. When it's turned one way, it's on and turned the other way it's off. This lever you turn is connected to a slot in a flow valve inside that can turn on it's own if you aren't careful when you take the lever out. Then it can appear to be on from the lever perspective but really partially off from an internals perspective. It restricts the fuel enough to cause fuel restriction that mimics all sorts of problems, yet it can allow enough fuel through to make you think it's working and restricted elsewhere. Tricky.

Bottom line...if you're reading this and have a Kubota with a fuel restriction or fail to prime issue, take a look at the water separator to see if fuel is coming out like it's supposed to. If it's not, unscrew the set screw that holds in the lever and turn the plastic slot inside with a screwdriver and try again.

 

[Gordon Gould]

Thanks for reporting back. Every time I saw your thread I wondered what you found. Sounds like indexing that water separator lever is a little tricky. Glad your good to go now.

gg