ZD 1211- Wanting fuel tank to equalize

[droy]

South Louisiana flatlander wanting to modify the fuel system so they will draw down equally. Thinking of removing stock setup from tank valves down, saving in case of resale; then mount a filter / water separator setup same as my L4740 so just have to stock one fuel filter. Haven’t looked at micron filtration difference, don’t THINK there should be any difference. Haven’t had success in finding the micron comparison.
Questions are - (1) Where are the checks that prevent the tanks from equaling?
(2) Should I retain the two “tank dedicated” filters even with the addition of the tractor fuel water separator?
Don’t want to compromise filtration but would like to make my life a little simpler.
Any thoughts / comments appreciated!

 

[RjCorazza]

View attachment 752279

The check valves are #80 in the above diagram. I thought about doing something similar when I had problems with the tanks not equalizing, but my issue was just that one filter was more clogged than the other. I stopped thinking about the ramifications of removing the small filters and connecting the tanks.

I guess if I were to do it, I would remove the check valves and filters then install my filter of choice after the "T" connection. I would find the space for a large Cat 1R-0750 2u filter.

My other mower is a ZD326 which has a different fuel setup. There is a manual valve to switch tanks, and (2) filters in series (one before the lift pump and one after). On this mower I removed the first filter and replaced it with a Cat 2u spin on.

 

[droy]

The check valves are #80 in the below diagram. I thought about doing something similar when I had problems with the tanks not equalizing, but my issue was just that one filter was more clogged than the other. I stopped thinking about the ramifications of removing the small filters and connecting the tanks.

I guess if I were to do it, I would remove the check valves and filters then install my filter of choice after the "T" connection. I would find the space for a large Cat 1R-0750 2u filter.

My other mower is a ZD326 which has a different fuel setup. There is a manual valve to switch tanks, and (2) filters in series (one before the lift pump and one after). On this mower I removed the first filter and replaced it with a Cat 2u spin on.

View attachment 752137

Thanks for the reply RjCorazza, for some reason can’t open attachment, message says I don’t have permission to perform this act. ???
Just a comment on your choice of fuel filters if you performed the modification. The secondary filter on my eighteen wheeler (C15 600 hp) is a 1R-0749, for a lawnmower that’s a BIG filter! I think I would look at one a bit smaller such as on C7 - C10 Cats. My truck also came equipped with a Cat #2693(?) as primary filter / fuel water separator. I replaced that filter base years ago & have been using a Baldwin 1397 SP which is considerably larger than the 2693. For peace of mind when I do the lawnmower modification I want not only filtration but also a water knockout. I am not a commercial cutter so I THINK the same base & filter that came with my L4740 would suffice. In our area, sweating / condensation in fuel tanks seem to be just as much a problem as clean fuel. Algae in the bio fuel is also a real PIA. For me another draw back of the stock setup is our weekly cutting consumes approximately 4 gallons & we refill when finished to prevent sweating / condensation so the fuel in other tank doesn’t really get used. Once I do the modification I will hopefully remember to post results. Hoping to go to town today, intend to visit with local Kubota parts manager, great guy lots of knowledge & willing to spend a couple minutes sharing it with you.

 

[5030]

Interesting. My saddle tanks on both my M series Kubota's are joined by a crossover hose with no restrictor valves at all.

 

[RjCorazza]

Thanks for the reply RjCorazza, for some reason can’t open attachment, message says I don’t have permission to perform this act. ???
Just a comment on your choice of fuel filters if you performed the modification. The secondary filter on my eighteen wheeler (C15 600 hp) is a 1R-0749, for a lawnmower that’s a BIG filter! I think I would look at one a bit smaller such as on C7 - C10 Cats. My truck also came equipped with a Cat #2693(?) as primary filter / fuel water separator. I replaced that filter base years ago & have been using a Baldwin 1397 SP which is considerably larger than the 2693. For peace of mind when I do the lawnmower modification I want not only filtration but also a water knockout. I am not a commercial cutter so I THINK the same base & filter that came with my L4740 would suffice. In our area, sweating / condensation in fuel tanks seem to be just as much a problem as clean fuel. Algae in the bio fuel is also a real PIA. For me another draw back of the stock setup is our weekly cutting consumes approximately 4 gallons & we refill when finished to prevent sweating / condensation so the fuel in other tank doesn’t really get used. Once I do the modification I will hopefully remember to post results. Hoping to go to town today, intend to visit with local Kubota parts manager, great guy lots of knowledge & willing to spend a couple minutes sharing it with you.

Uhmmm. Don't know why the image doesn't work. The check valves are immediately after the output of each tank filter (filter > check valve > T).
Yes, the Cat filter I used on the zd326 is large. I mounted it on the rear outboard frame rail. I installed the same filter on my previous zd331. I filter my fuel for water coming out of a transfer tank with a 10u water blocking filter, and go through both tanks in just under a week, so water had not been a problem for me over the years.
A water separating filter sounds like a good idea for your machine.

Report back with the finished product!

 

[droy]

Interesting. My saddle tanks on both my M series Kubota's are joined by a crossover hose with no restrictor valves at all.

Assuming you are referring to the tanks on your M series tractors, while I am discussing a zero turn. But interesting point as the reason I was given for the check valves being there is to prevent fuel from leaving one tank overfilling the other when mowing on slopes. Guessing that Kubota doesn’t feel a tractor will spend enough time on the slope for that to happen.
By coincidence I made a delivery to LaFayette Georgia couple weeks back, while on I-59 saw the “St. Augustine Daredevils” mowing alongside the interstate. While held up in construction I watched as one guy left the grassy area of an overpass slope, crossed the sloped cement pad under the roadway to continue mowing on the other side. When he got onto the grass he lowered the bat wings & continued mowing. Only then did I realize I was not only in an advanced stage of pucker factor but also white knuckling the steering wheel mentality straining for that guy. My only slope to deal with is a head row type levee on south side of my property. Actually on my neighbors property I often use it & keep it mowed. Couple years ago while mowing it I turned to look back at the shredder next thing I felt the tractor lean, turned back around in time to see me go into his crawfish pond! Top of the head row is only about 2’ above waterline & pond only about 18” deep but thinking I was about to turn over it was truly an “AW $H!T” moment!

 

[WM75Guy]

"But interesting point as the reason I was given for the check valves being there is to prevent fuel from leaving one tank overfilling the other when mowing on slopes."

I keep mine stock for just that reason. For me running out has never been an issue. The gauge works off the right-side tank. When I was using cans to fill up I always put more in the right tank so when the gauge was down to a 1/4 tank, it was time for fuel. I did notice at times that the left was empty then. But I never was stranded out of fuel. Now that I have a fuel trailer I top off both tanks after mowing before I park it.

 

[5030]

My Cub Cadet 60" tank has twin fuel tanks and I'm not sure if there is a check valve or not, don't believe so. I need 2 tanks as the Kawasaki motor is a pig on gas.

 

[Brown Dog]

...
By coincidence I made a delivery to LaFayette Georgia couple weeks back, while on I-59 saw the “St. Augustine Daredevils” mowing alongside the interstate. While held up in construction I watched as one guy left the grassy area of an overpass slope, crossed the sloped cement pad under …..

Lafayette is only 30 miles NW of me.
Those guys are brave mowing the right of ways

You definitely DONT WANT one those tractors after they trade them in @ 2k hours. Trust me.

I like watching them.

 

[Tinhack]

Thanks for the reply RjCorazza, for some reason can’t open attachment, message says I don’t have permission to perform this act. ???

My computer just says, "Couldn't find that". --On both attachments.

 

[workinonit]

I'm a bit confused abiout these fuel tanks as well. I didn't realize they had check valves. I know mine has a bypass line in the top of the tanks to equalize the preassure. I could have sworn when I first brought mine home the dealer fille the left tank, the right was almost empty and after trailering home and running for a while the gauge showed 1/2 tank. So I assumed the tanks equalized but apparently that wasn't the case. My concern is if this particular unit tends to run fuel out of the left tank first I could run out of fuel with a full right tank. I thought about closing thge right hand tank valve and running the left first before valving the right back in. It's kinda cheesy that they didn't put gauges on both tanks.

 

[Brown Dog]

… the check valves being there is to prevent fuel from leaving one tank overfilling the other when mowing on slopes."

I keep mine stock for just that reason ….

Mine is still stock as I mow a LOT of horizontal swipes on Steep Banks in both directions.

I’ve noticed sometimes one of my tanks holds more at fill ups than the other side & in no particular pattern

 

[Brown Dog]

Anybody else have input on tanks drawing equally ?

 

[RjCorazza]

I removed the individual tank filters and installed the OEM filter after the "T" fitting. My tanks were occasionally drawing unequally due to one filter having a higher resistance. I also added large 2u Racor filter and an extra lift pump to get adequate flow.
So far it's been working fine, but I suspect my service interval will be shorter with the fuel from both tanks going through the one OEM filter. 120h so far using the old smaller type, so I'm not worried about it.

 

[Brown Dog]

RjC
Do you still have the OEM check valves in place ?

 

[RjCorazza]

RjC
Do you still have the OEM check valves in place ?

Yes, I left the check valves in place.
I agonized over several plumbing possibilities... There are lots of ways to skin the cat.

 

[BobinCols]

My ZD1211 drew pretty equally the first three years since new. Then the right hand tank (as sitting on machine that has the fuel gauge) always stayed full. I could turn the left hand tank fuel valve off and it would run fine off the RH tank and fuel and gauge would go down. Blew air in fuel cap vents etc..
Finally two weeks ago I purchased two new filters from Kubota and removed the checkvalves. Sadly the check valves are 5/16" on inlet end and 3/8" on outlet end. So that means the "T" has two 3/8" inlet ends and the outlet is 5/16" that goes to the motor. Trip to parts store to get a "T" that was 5/16" on all three sides and a short piece of 5/16" fuel hose to fill in the areas where the check valves were taken out. Now draws from both tanks again. Hope this helps.

 

[RjCorazza]

I removed the individual tank filters and installed the OEM filter after the "T" fitting. My tanks were occasionally drawing unequally due to one filter having a higher resistance. I also added large 2u Racor filter and an extra lift pump to get adequate flow.
So far it's been working fine, but I suspect my service interval will be shorter with the fuel from both tanks going through the one OEM filter. 120h so far using the old smaller type, so I'm not worried about it.

I updated this in another thread, but FYI my uneven fuel draw returned and I converted the fuel system back to stock.
It seemed to draw equally for a while, but after maybe 30 hours (?) it mostly draws from the left tank. I can live with it but it bothers me. Curiously, the left filter is always 1/2-3/4's empty of fuel, while the right filter is always full. When it was drawing equally both filters remained full.
As far as the check valves, I mow on a lot on inclines and don't want the fuel moving from the high side tank to the low side so I'll leave them on.
I'm starting to think this whole problem is caused by slight manufacturing tolerances in the filters themselves. I plan to switch the current left and right filters around and see what happens.