Help Needed: Bleeding MX5100 Fuel Filter

FatTire · Dec 23, 2013

Changed fuel filter today on my MX5100, following the steps in the Op Manual for bleeding. But the engine shut down just before I closed the bleed valve and will not restart. Apparently the next step would be to bleed one (or more) of the fuel injection lines, but how do you get to the top of the block on the MX5100 to do that? I cannot get a wrench on any of them. Remove the fuel tank???

NOTE: I could see there was air in the bowl, but the Manual doesn't say to fill the bowl so I thought it would be OK. Maybe that was my mistake.

I talked to a mechanic at my local dealer over the phone. He thought I should be able to reach the injector, I don't see how. He will come up after Xmas if I can't get figure it out. I guess there is the same issue with getting to the glow plugs.

rayclar · Dec 23, 2013

Did you turn your fuel shut off valve back on? After changing my filter this fall, assembled everything, opened shut off valve and the bowl filled right up. Opened bleeder on pump and ran for 30 seconds, closed bleed screw and all was fine.

FatTire · Dec 23, 2013

Yes, opened valve, bowl filled about 1/2. That was the unusual part, I should have stopped at that point.

dex3361 · Dec 23, 2013

I think there is a self bleeding jet start system on this engine. The valve is located on the injector pump and you open he valve and crank the engine over when it starts shut the valve off. I am going from memory here but it was about the easiest priming fuel filter change I have ever seen. You can go to Kubota parts list online and look up the valve on in the engine catagory under the injector pump section. It is listed as item # 080. KUBOTA PARTS DIAGRAMS ONLINE

JC-jetro · Dec 23, 2013

fat tire,

What you see below is a transfer pump that is lower than the outlet on the fuel filter. That provides fuel to the fuel pump.

On the pic below , follow the discharge pipe up to a round knob (just about the oil cap). That knob has a bypass that goes all the way to the fuel tank. You need to open that round knob by hand pressure. You then try to start a few time so it can expel the air back to the tank. You will not see any fuel bubble. That procedure should be enough.

if you follow 4 lines from top of the fuel injector pump lead you to where it enters the pistons. Yo u can bleed it there but I do not recommend it as it is not recommended on (WSM )Work Shop Manual).

JC

dex3361 · Dec 23, 2013

JC-jetro pics shoe the jetstart valve that I was describing and his is much easier to understand.

JOHNINMA · Dec 23, 2013

Do you have a full tank of diesel? On my tractor I changed the fuel filter and had a similar problem where it ran briefly then would not start not matter what. I filled the tank from a quarter tank to full out of sheer desperation and it started instantly allowing me to finish bleeding. No problems since.

FatTire · Dec 23, 2013

Thanks for the input guys. I opened the air bleeder valve (same as shown nicely by jc-tretro) before cranking the first time, the engine ran, and then died just as I was about to close the valve. BUT, no, my tank is only about 1/2 full. Tomorrow I can fill it and try again. I will do back flips if filliing the tank does the trick.

Tx Jim · Dec 24, 2013

You can also apply ""short bursts of compressed air"" into fuel tank neck while blocking remainder of filler neck with a rag in lieu of a full tank of fuel to speed up bleeding process. I think since you got it to fire you should not need to bleed injectors to get it to run.

The Fred · Dec 24, 2013

JC-jetro said:
fat tire,

What you see below is a transfer pump that is lower than the outlet on the fuel filter. That provides fuel to the fuel pump.

On the pic below , follow the discharge pipe up to a round knob (just about the oil cap). That knob has a bypass that goes all the way to the fuel tank. You need to open that round knob by hand pressure. You then try to start a few time so it can expel the air back to the tank. You will not see any fuel bubble. That procedure should be enough.

if you follow 4 lines from top of the fuel injector pump lead you to where it enters the pistons. Yo u can bleed it there but I do not recommend it as it is not recommended on (WSM )Work Shop Manual).

JC

EXCELLENT post JC. This gentleman's transfer pump or lift pump is air locked, simply pull the line off the transfer pump (top photo) that goes to the injection pump and draw a slight vacuum on the line allowing the air bubbles to clear up, THEN start the engine with the bleeder valve open.

Fred

JC-jetro · Dec 24, 2013

The Fred said:
EXCELLENT post JC. This gentleman's transfer pump or lift pump is air locked, simply pull the line off the transfer pump (top photo) that goes to the injection pump and draw a slight vacuum on the line allowing the air bubbles to clear up, THEN start the engine with the bleeder valve open.

Fred

That's right Fred. I was not able to find a detail of the transfer pump but it has to be a diaphragm operated pump that is driven by a cam of some sort. pretty much like old mechanical fuel pump on vintage American vehicles driven by cam or crankshaft combination. A hand operated Mini vacuum system like "mityvac" will be all it needs to draw the fuel thru the transfer pump. Since the fuel tank is atmospheric and the transfer pump is below the level of fuel, just taking the discharge hose on the transfer pump might be enough. I suppose one also can use a 2 foot section of clear tubing and try to siphon by mouth and watch the level of fuel in the tubing.

JC,

rayclar · Dec 24, 2013

If your fuel filter bowl filled 1/2 way then stopped you might have some dirt somewhere between the tank and fuel filter?

Chilly807 · Dec 24, 2013

I think part of the problem may have been screwing the filter bowl on too quickly. On my L3400, there is a valve in the rim of the fuel filter mount that shuts off when you remove the bowl to prevent spillage. Once you've replaced the element, screw the bowl on until fuel begins to fill the bowl, once it's full and starts dripping over the top, screw it on the rest of the way. This will fill the filter completely and it's less likely to air lock. The MX5100 may be different?

The injector nuts are accessible, but a PIA to get to.. no one said it was going to be easy

Sean

PHILLIP G · Dec 25, 2013

I have a mx5000, I always fill filter with fuel when re- installing to cut down on air in system. Always starts right up.

PHILLIP G · Dec 25, 2013

From my experience it would help to first make sure filter is full of fuel, make sure line from filter to injector pump is purged of air. Will need to take line loose at pump to release air from line, should be fuel with no air bubbles. If that doesn't get it going, you could loosen injector lines at pump to purge air from pump, will have to turn engine over to do this. When fuel only comes out, tighten line. You may have to repeat on other injector lines. Use caution when loosening injector lines, if fitting doesn't swivel on line, the line could break.

sixdogs · Dec 25, 2013

Fill the tank with fuel. Kubotas like this need a full tank on a fuel filter change and I'm near certain the MX5100 owner's manual details it. This should solve the problem unless the partial tank compounded the issue. Problem should be solved.

Tx Jim · Dec 25, 2013

sixdogs said:
Fill the tank with fuel. Kubotas like this need a full tank on a fuel filter change and I'm near certain the MX5100 owner's manual details it. This should solve the problem unless the partial tank compounded the issue. Problem should be solved.

Not just Kubota's like their fuel tank FULL on fuel filter change but all tractors I've worked on are easier to bleed fuel system with a full tank.

sixdogs · Dec 25, 2013

Tx Jim said:
Not just Kubota's like their fuel tank FULL on fuel filter change but all tractors I've worked on are easier to bleed fuel system with a full tank.

Agreed.
Also, I have owned a number of tractors over the years and what works for me on a fuel filter change is first to run the tractor until it's fully warmed up from use. Then I immediately change the filter, fill the canister with fuel and try to start it. It almost every case it starts and I often avoid the need to bleed the fuel system. Beat me but it seems to work except sometimes on my John Deere 5520.

Chilly807 · Dec 25, 2013

I was expecting to have to bleed the system when I changed my fuel filter, but I just made sure the bowl was full and it never missed a beat after starting.

Sean