Adding a gas tank

[Silvaire]

Lou,

I like your drawing.

You show the return line going from the carb to the Whizzer tank. I think this would be the correct way to plumb things, and you would then NOT need gravity flow from the Whizzer tank to the Tanaka tank.

With the Tanaka tank sealed, suction from the carb would then suck fuel from the Whizzer tank via the Tanaka tank. Only if the Whizzer tank is vented (and with the return line going to the Tanaka tank) would it need to be higher than the Tanaka tank. If both tanks were sealed it wouldn't matter which tank was higher as long as the suction was from one tank and the return to the other tank.

With it set up as per Lou's drawing, I believe that ZevO is absolutely correct, and that you would not need gravity flow for any part of the system. For some dumb reason I was thinking vented cap and float type carb...

 

[Zev0]

Ok, I don't have a picture at the moment nor am I any good at drawing, but here's how we do it. We seal off the cap on the main tank, run a hose from the aux tank into the top/side/whereever through a gromlet. Both hoses from the tanaka carb still run into the main tank. Don't know if you can grasp what I'm saying, but there's a lot of us that run it this way. BTW it works the same on a Robin/Subaru.

 

[augidog]

this is the method "we" use: http://www.motoredbikes.com/showthread.php?t=7821

 

[Silvaire]

Zev0,

I believe that understand how you have your system plumbed up, but I don't see how it could work.

If both fuel lines from the carb go to the original Tanaka tank (which is sealed), and the aux tank is lower than the Tanaka tank, the only way I can see that it could work would be if the net effect of both the feed and return lines created a negative pressure within the Tanaka tank. Perhaps it does, or perhaps there is some other explanation that I haven't considered.

One thing I've learned in life though, is that you can't argue with success...

 

[Zev0]

Silvaire, all I know is that it works for me and many many others.

 

[augidog]

Silvaire, the above link describes the setup being discussed...the one everyone in town is using successfully...someone should bump it once in a while, or maybe the mods can find a better place for it?

note: the 40 has a check-valve style vent instead of a breather-cap...this means it already has the extra hole needed, get it? take the check-valve out, get the appropriate grommet, move everything down one hole, add the aux line in the top hole.

 

[5-7HEAVEN]

I'm not sure what your referring to. What and where is the fuel grommet?

I'm also not sure where the vent is on my engine. Does every engine have a vent?

Your talking to a novice here that's why I need pictures.
Haha!!!

The fuel grommet is that black rubber fitting on the engine tank. That is where the two fuel lines enter the engine tank. it is usually located atop the engine tank.

Every engine tank has a vent. Usually it's the gas cap that is vented.

 

[shawnshank]

I just took a look at the owners manual. It has a vent on the top of the tank and two fuel lines.

page 5 of the manual: http://www.tanaka-usa.com/pdf/dpl/utility/PF-4000dpl.pdf

Now people can refer to the numbered parts I need to modify if that helps.

Does the Tanaka have 2 hoses from the carb to the tank now?

If yes, one is the fuel line, and one is the fuel return line. The engine has a diaphram style fuel pump; it pumps more fuel than is needed, and the excess, along with enough air volume to replace the missing fuel is routed back to the tank.

This means that any additional tank/fuel lines you add should

1. Be a closed, airtight system, and
2. have a fuel line 'loop' in the plumbing. Ref the attached sketch.

 

[5-7HEAVEN]

I installed a 4-liter Happy Time reserve tank to supplement my 1.5 liter goped tank. It has a petcock, inline fuel filter and line to feed the goped tank, which is mounted directly across my friction drive engine.

Since the new goped tank was leaking profusely from the fuel grommet, I patched that hole and moved the fuel and return lines onto the top.

Thennn, I drilled another hole atop to accept a 1/8 NPT 90-degree fitting and nipple. This connects to the reserve tank. I also installed a draincock on the g-tank.

When I open the Happy Time petcock, natural siphoning action fills the goped tank to the brim in minutes.

Now I can carry 186 ounces, which is almost 8 times the fuel supply on an engine tank, about one gallon, 3 pints and 10 ounces.

 

[uncle_punk13]

this is the method "we" use: http://www.motoredbikes.com/showthread.php?t=7821

I use this method as well on my 40cc Tanaka.
Question:
If I use a non-vented cap on my R/S 4-stroke, can I plumb it wit the same method using the Auxiliary tank with vented cap ?