Hard to start M7040 with cab

[rpmranch]

I have a 2010 7040 cab model with 4 wheel drive with 383 hours on it. The tractor started to idle rough and then if finally died like it ran out of fuel. I went ahead and changed out the fuel filter (400 HR maint) and cleaned the water separator, bled the system as the repair manual states.

Now the darn thing will start but dies like it is out of fuel. I bleed the system again and after multiple tries it will start and run like a top for hours but if I shut it down and let it sit it will do the same thing.

I have disconnected all the fuel lines and blew them out, bled the system again and it is still doing the same thing when I try to start it.... I ran it yesterday for over an hour dragging some pastures but today it did the same thing. I have noticed that when the tractor is running the fuel level in the water separator bowl varies and does not stay at a level amount?? Never seen that before....

I have two Kubota's using the same fuel out of my bulk tank, the other tractor runs fine so I don't think its the fuel. I keep additives in the bulk tank as well as the tanks on the tractors.

Anybody have any ideas???? Winter is coming on and I sure don't need to be bleeding the system every time I try to start it.....

 

[North Idaho Wolfman]

Things to check,

Plugged vent on cap or tank.
Bad /internally collapsed fuel line.
A loose fitting or cracked fuel line.
Plugged fuel return line.
But my money is on a bad fuel pump or lift pump.

 

[rpmranch]

I checked all the fuel lines and vent. Talked to one of the shop guys today at the dealer, he thinks it has bleed off problems. Either a bad o-ring on the fuel separator or the fuel filter bleed pump is releasing the pressure. Seems to think it is a priming problem. Tend to agree, the tractor runs fine once it is running. Off to get a O-ring for the separator tomorrow and run a pressure test on the bleed valve on top of the fuel filter housing.... Hate to think it is a fuel pump or lift pump. $$$$$

 

[North Idaho Wolfman]

Looked over the schematic, and there is 2 check valves that could also be causing you issues.
Check valve #1C010-42460 $29.66

The fuel pump is not too bad if that's what's wrong, but thinking about it, I think it could be as simple as an o-ring or maybe a check valve, check valves would be simple to pull and check.

Fuel pump #1C010-52032 $121.59

 

[Tx Jim]

Ditto what Wolfman stated on the check valves. I had trouble last Winter with my M7040 because I got a little water in the fuel tank and the check valve froze up causing engine running problems. Since then I've removed the water from the tank.

I've also experienced a very small white screen in the water separator shut-off valve that was limiting fuel flow that required cleaning on a M4900 that I sold to buy my M7040

 

[rpmranch]

Going through it today to see what I can find out. Will let you know what I find out. Problem is once it is started I will have to let it sit each time for the prime to bleed off to see what I replaced worked. Just might pick up the check valve today while I am at the dealer... Think I will put out hay before the cold front comes in, that way I don't have to fight the weather and the tractor.....

 

[rpmranch]

Well, I changed out the O-ring for the fuel/water separator. No change so I replaced the lift pump and bled the system and drove it for about 1/2 hour. Let it sit for a couple of days and it started right up.

I still have the fuel level moving up and down in the separator bowl. Not sure what is causing that, I have blown out the lines all the way back to the tank.

I took it out to drag some pastures with a harrow, stayed out an hour.
During that hour the tractor acted like it was running out of diesel on three different occasions. I thought maybe it was due to pulling a load up a grade, but the last time it happened I was going downhill....

I have re-inspected every fuel line, every connection and for the life of me figure out what is going on....

Mechanic at the dealer still thinks it is sucking air somewhere.... Not sure if I agree.

 

[GWD]

It seems to me that the fuel level in the separator bowl must give a big hint about the issue. My 7040's bowl is always full to the top.

It was mentioned before, but have you taken the fuel tank filler cap off and then observed the separator fuel level? The tank might not be venting.

Another possibility is that there is something in the tank that is plugging the pick-up line. You mentioned that you blew out the line to the tank from the bowl but something in the tank would shortly be sucked over the pick-up line. Maybe algae?

The only way to know for sure is to remove the tank, pull the fittings, and flush it all out. Oh, boy...what fun.

 

[North Idaho Wolfman]

Usually fuel moving up and down in the separator bowl will mean that air is getting into the system, and air in the system will cause the problems your explaining. You should be able to bleed it all out and it should stay that way. It could be as simple as a pinhole or crack in a fuel line, or it could be a crack in the filter housing or a fitting.

 

[rpmranch]

I use diesel Mechanic in a bottle to treat my fuel so I am hoping I don't have to drain a full tank of fuel. Seems funny my other tractor runs fine on the same fuel out of the same bulk tank.

I have checked every fuel line, vent line and connection so I think we can rule those out.

Watching the level of fuel at the separator leads me to believe it is sucking air somewhere because of the type of bubbles that appear when the level of fuel changes.

I have not let it sit long enough to see if the prime bleeds off, that was the first of my problem and now I am not sure if even that is fixed.....

 

[North Idaho Wolfman]

Did you change the check valves?
If one of those is bad it can put air back into the separator.
If you can see bubbles coming into the separator then it defiantly has air getting into the system from somewhere!

 

[rpmranch]

I looked at the schematic, I would assume the two valves you are talking about are down stream of the fuel filter which has the bleed pump on it. I would assume that the pump would have a check valve built in to it as well so no I have not changed them out yet. But that is just an assumption on my part which has probably made an ass out of me.... the tractor does run so I am thinking I will systemically go through each line and clamp until the tank is low then drain the tank and clean it. My first plan of attack is to change the lines and clamps out that I have touched, then go from there....It has to be something I touched, just don't know what....

The dealer has told me the same thing as you have stated, guess it will I will have to go line by line, clamp by clamp and part by part to sort it out... He said they would have to do the same.... Bummer......

PS: Grew up in Twin Falls and left to join the Marine Corps. Would have went back if the job market would have been there... Miss the mountains, rivers and hunting....

 

[Tx Jim]

rpmranch
Local Kubota dealer service manager told me the check valves on fuel return line were unnecessary and engine would run fine without them. Have you checked for plugging of the small screen in water separater housing fuel shut off?? Your tractor acts similar to the one I had that the screen was plugged.

 

[rpmranch]

Not yet, went down and purchased new screw type hose clamps to for all the fuel lines I have been messing with. I will do that while I am changing out hose clamps. Probably be in the next couple of days.

 

[rpmranch]

Well, I tore the fuel system down and found the problem. Looks like there was a wad of garbage inside the fuel/water separator housing. Not sure how it got there but it did. Not sure how it got past the fuel shutoff valve but it did. All is good now.....

Thanks everybody for the help.......

 

[North Idaho Wolfman]

Excellent to hear!

 

[Tx Jim]

Well, I tore the fuel system down and found the problem. Looks like there was a wad of garbage inside the fuel/water separator housing. Not sure how it got there but it did. Not sure how it got past the fuel shutoff valve but it did. All is good now.....

Thanks everybody for the help.......

Did water seperater housing have a tiny screen similar to the M4900 I referred to?

 

[rpmranch]

Did water seperater housing have a tiny screen similar to the M4900 I referred to?

No sir, it did not.

 

[GWD]

Thanks for reporting back about the solution. It is always good to hear a happy ending.