OH BOY - Fuel tank!

SwampCat

Member

Equipment
B7510 HSD
Jun 7, 2015
72
0
6
Northern,Wi. U.S.A.
:eek: When it rains ,it pours. This all started out with cleaning up the damage caused by a leaky battery, had the radiator out, fan off, dynamo off, basically had EVERYTHING off of the front, except the oil cooler. Got all that cleaned up and repainted. In my infinite wisdom I figured I would lube the 10 yr old tach cable while everything was exposed. So far so good. Got it all reassembled, fired it up to heat up the system and check for leaks, first thing I notice, the tach is not working. Well cable is not broke, because I just had it out to clean and lube it. Maybe it did not seat in the drive ? After 3 installs of the tach cable at the engine, I know its seated in there correct. Pull it out 1 more time, this time I hook the cordless drill to it at the engine end, guess what still no tach. Now, off comes the dash, lo and behold the knurled nut fell off the back of the tach. BUT after driving out the roll pin that held the throttle lever on, it goes sailing off into the depths of behind the dash. Now the whole dash has to come off to look for the pin. Upon getting the dash off, I notice the back of the fuel tank is all sucked in and COLLAPSED :mad: mind you I just got this thing 2 weeks ago and had not really used it much yet,it was time for its 300 hr service so I figured, what better time to get to know what makes this thing tick. And yes the tach was working before all this started. So, any ideas WHY the tank collapsed, this cant be a common problem. While I have the tank out is there any thing ELSE I should do or check while waiting for the NEW tank to arrive. Dont really think its a good idea to try and salvage the old one. When I say collapsed I mean the back of the tank is sucked in 4-5 inches. SORRY for the long story,but I just had to get this off my chest. Thanks for any insight or ideas on this.
 

CaveCreekRay

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L3800 HST, KingKutter box scraper, KingKutter 66" rake, County Pride Subsoiler
Jul 11, 2014
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Cave Creek, AZ
I am thinking your cap is not venting and allowed the fuel pump to pull a vacuum on the tank. Not good! Get yourself a new cap before you fire that thing up!!!:eek:

Good luck!

Ray
 

mendonsy

Active member

Equipment
B7500HST/LA302
May 28, 2012
361
37
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Mendon, NY
It seems like there must be something more going on here. There is no question that the caps can plug up and cause a vacuum in the fuel tank, but the engine will normally stop from lack of fuel long before it collapses the tank.
 

Grouse Feathers

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BX2370, FEL, Snowblower-BX5455, Homebuilt Forks, LP RB1560, LP GS1548
Feb 16, 2015
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Lovells, Mi
This is a shot in the dark. If the vent was plugged and it sat over the winter, the pressure in the tank would go down as it got colder and could collapse the tank.
 

SwampCat

Member

Equipment
B7510 HSD
Jun 7, 2015
72
0
6
Northern,Wi. U.S.A.
Well, in my search of this tank problem, I ran across a picture of another tank that looked just like mine. Seems this is more common than it should be. Maybe Kubota sent out a bad batch of fuel caps ? There is deffinitly a venting problem.
 

SwampCat

Member

Equipment
B7510 HSD
Jun 7, 2015
72
0
6
Northern,Wi. U.S.A.
Messed with this thing a little more. Yes, compressed air did blow it back out, rather easily. I still for the life of me, DONT see how this tank is vented. The liner in the cap is chambered, but it still does not go to atmosphere. The 2 small lines in the upper right corner, one goes to the filter, the other looks like it goes to a injector ?
 

North Idaho Wolfman

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Jun 9, 2013
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Is there cuts in the threads on the inside, if so that's how it vents. ;)