Fuel line connector problem

[Tibbits]

The top of the fuel tank of a Kubota L3430 has 2 fuel lines connected - one routes to the injectors and one to the fuel filter. There is a nipple for each hose sticking out of the fuel tank to connect the fuel lines.

Well, I noticed a slow leak on the line that connects to the fuel filter, and when checking it I discovered the nipple is broken (on the fuel tank) and just dangling. The parts diagram seems to show the nipples as part of the fuel tank? I don't want to replace the fuel tank!

Has anyone had this problem and how did you solve it? I'd like to find a way to 'fix' the nipple and connect the hose without a lot of time or money involved. Some type of 'screw in' nipple would seem to fit the bill.

As background, this fuel line does not seem to be needed a lot. I think it exists to relieve excess pressure from the fuel filter. I only notice a small leak when I fill the fuel tank completely full, so I assume some leaks out the broken nipple as the fuel sloshes over it. I'm more concerned about keeping dirt out of the tank than the little bit of fuel that leaks out. Any ideas (other than a new tank!) would be appreciated.

 

[Argosy]

Does it have a cap big enough to get your hand in (or most of the way in) the tank? If so look for a bulkhead connector. Drill the right sized hole, they use a jam nut inside the tank to seal, put the right fitting in to mate to the hose . Make sure the hood will clear.

Plug the old hole with an automotive gasket maker that is diesel resistant.

 

[Tibbits]

I like that solution, Argosy. but I'm afraid I don't have enough room with the cap opening to work with. I'll check I'm the morning.
the gasket maker might get me by. since this is just an over flow line and rarely carries fuel, I may be able to glue a fitting to the existing hole with the gasket maker. might work. and if doesn't, no harm done. thanks.

 

[JoeL4330]

I'm a little confused...the line to the filter is the feed, I would think, and the other is the fuel return line.

Hard to believe you won't have to remove the tank, at the least to address this.

If you are looking for a shade tree solution, perhaps you might connect the good nipple to the fuel filter line, block the other nipple, and re-route the return line somewhere into the tank ...say, at the top near the filler.

I'll look at my shop manual (L4330) in a bit and see if that helps ...

still, once the tank off/accessible, there are solutions that can insert a new fitting from one side only

 

[Tibbits]

The broken nipple appears to be the 'fuel filter air vent pipe' shown on the diagram. The only time I have noticed any leakage was when the tank was full, so I'm thinking a quick fix may be OK...as long as it doesn't leak and keeps dirt out.

 

[E/S]

Plastic weld it?

 

[Tibbits]

not familiar with 'plastic weld' but I think I might be soon.

 

[jonyyuma]

Permanent repair?If you don't like plastic weld, Have you considered tapping out the hole with a pipe tap and screwing in another nipple for the return line?There will be a few shavings, but use soft grease on the tap and clean it often. Pipe taps match screw in nipple fittings. Just a free thought?

 

[Tibbits]

I really think the tap method is best. now, to find a fitting with threads and male connector should be fun!

 

[JoeL4330]

(sorry about my post, above...didn't realize the hose came in at the top...vent/return)

as for tapping, my tank would be too thin to get any/many threads so holding would be a problem ...and, despite some advertisements there don't seem to be any adhesives/epoxies, etc. that are designed both for the plastic and for fuel (at least, gasoline) ...heat welding is how it would be done, but that seems out of the OP's range. Rather than tap, it would be ideal to use a nut on the back-side (i.e., inside) but as currently located, I'm guessing that holding the nut through the filler opening would be problematic.

I might consider patching the current hole (maybe tapping and patching with some epoxy or other fuel gasketing mush and then relocating the fitting to the top of the tank, reachable through the fuel-filler opening ...using a right angle fitting threaded on the inside and with fuel-resistant washers on inside and outside.

 

[Soundguy]

what about a tire schrader valve with no core....

soundguy

 

[Tibbits]

Hmmm. All good info - thanks to all. Seems the only good way to fuse the plastic involves heat + diesel fumes + experience. Getting old has one advantage - knowing what I shouldn't attempt and that is one of them.

The schrader valve is interesting. If I hollow the core and use a plain drill bit slightly smaller than the threaded end of the valve, I may get enough bite in the thin plastic to make it work. Again, I think this line mainly equalizes air pressure and rarely carries fuel, so this may work. Hopefully a metal fitting will co-exist with plastic and not cause problems like different expansion rates.

 

[Ken]

Hmmm. All good info - thanks to all. Seems the only good way to fuse the plastic involves heat + diesel fumes + experience. Getting old has one advantage - knowing what I shouldn't attempt and that is one of them.

The schrader valve is interesting. If I hollow the core and use a plain drill bit slightly smaller than the threaded end of the valve, I may get enough bite in the thin plastic to make it work. Again, I think this line mainly equalizes air pressure and rarely carries fuel, so this may work. Hopefully a metal fitting will co-exist with plastic and not cause problems like different expansion rates.

Consider GOOP brand Plumbers weld glues anything to anything and makes seals on pipes hot ot cold.
I keep a tube in shop for plastic seal of leaks. just clean area and apply
ken

 

[Soundguy]

Hmmm. All good info - thanks to all. Seems the only good way to fuse the plastic involves heat + diesel fumes + experience. Getting old has one advantage - knowing what I shouldn't attempt and that is one of them.

The schrader valve is interesting. If I hollow the core and use a plain drill bit slightly smaller than the threaded end of the valve, I may get enough bite in the thin plastic to make it work. Again, I think this line mainly equalizes air pressure and rarely carries fuel, so this may work. Hopefully a metal fitting will co-exist with plastic and not cause problems like different expansion rates.

those tire valves should have a expansion plug base and a groove.. that's where they seal to a rim.. I would think it would work great in your application.. drill the hole so the valve can be forced thru but tightly ( use grease ).. and it should seat.. then just remove the valve core.. then use fuel line to couple her up.

i've put tire valves on non vented gas cans and then removed the valve and screwed the cap back on.. remove cap when pouring.. etc.



soundguy

 

[Tibbits]

OK, tire valve is the plan. I'll stop by and see my tire guy on the way home today. I assume the best type has a push in bulb at the base. Also, seems best to remove the valve before I insert/seat the valve housing?

 

[Soundguy]

doesn't reall matter when you remove the core.. it's done externally with a core tool.. whatever you have room for.

all the valve stems I see have a lip at the base to retain them inside the rim, and the base of the tube is an interference fit with the stem hole, and some even have a raised rib there to help.. should be a good fit.. may have to seat the valve thru the opening in the tank and push it outwards till it clicks into the hole you opened up for it.. but shouldn't be doo hard. again.. i've done these with the red plastic abs style gas cans..

soundguy

 

[Just Bill]

The valve stem is a great idea and would be the easiest and permanent repair.
You could also use a threaded brass valve stem that uses rubber gaskets and nuts, if you have the room.
Drill the hole and make sure everything fits right.
Thread a wire through the hole and out of the fuel neck,
slide the fitting on the wire and pull it through the hole.

 

[David_Kb7uns]

They make a rubber fuel line "grommet" or "bushing" that fits into a drilled hole in a polly tank and then the metal angled fuel line nipple is pushed in and locks it to the tank.

Amazon.com: Oregon 07-392 Fuel Tank Bushing that Fits a 33/64-inch Diameter Fuel Tank: Patio, Lawn & Garden

My RTV 1100 uses similar connections for the return and fuel filter vent/purge lines.

David Kb7uns

 

[Tibbits]

Thanks David Kb7uns. I think that would fit better than the tire valves I've been able to find so far. Last night, I ended up trying the Plumbers Goop to re-attach the broken part of the fitting to the tank. I ran a wire through the opening to make sure the Goop didn't close any of the opening as it set, and so far it appears to be a good seal with decent strength.

I will avoid filling the tank too close to full to minimize the slosh reaching the repaired nipple. Usually, the only time I completely fill the tank is winter storage to keep tank condensation down (not sure if that even applies to a plastic tank).

If the adhesive does not work, you guys have provided plenty of 'Plan B' options that don't involve a lot of time or money. Thanks!

 

[Soundguy]

good luck.

soundguy