Still kinda confused about my gas tank???

[kelseydum]

Most of you know I'm new to this and this is my first keg gas tank. I know this is pretty simple, but I'm not quite understanding one thing. The drawings and pictures of keg tanks I've seen look something similar to this...

However, in doing research I noticed that a carbureted motor only needs an outlet and not a return... Is this correct? If so do I only need one hose fitting on the bottom? The cap will be vented so no need for an extra vent, and I'm just going to use a dipstick to check my fuel level.

On my list of items to get are:

1. My aluminum filler neck and vented cap.

2. 1 aluminum fitting for the outlet (goes on bottom of tank).

Also in just trying to understand things as a whole better I have one more "stupid" question. On the older motors the fuel pump connects to the motor instead of close to or in the gas tank on newer models. How does the fuel flow through the system? Does the fuel go from the tank to the fuel filter then to the carburetor? Is there some left over gas that isn't burned, and does that go back to the tank (hence needing a return line)? Like I said, I'm a little confused and really new to this so any help is appreciated. I've done a ton of research but can only find so much info.

I found this pic that Bonehead (I think) posted, but is this for a fuel injected motor?

 

[dmw56]

No return line needed on a carbureted engine. The standard vacuum fuel pump doesn't put out a lot of pressure so the excess fuel is just dead headed in the fuel bowl.

So all you need is a filler and outlet. With the outlet on the bottom put in shut off valve.

 

[Bonehead]

One out the bottom will probably work. But even alot of the old non-fuel injected engines had return lines. Most of them stayed dry. You might consider a sight gauge, but a dipstick will work fine.

 

[Gastrick]

Like the others said KD, you don't need a return line with your combination and as you already know, with the vented cap, you only need one outlet on the bottom of the tank. You should have a filter inline before the pump. With a standard mechanical fuel pump, you won't need an external regulator either. Some electric pumps are internally regulated and don't require an external regulator either.

With your scenario, I would just install a single outlet at the bottom of the tank and run a fuel line from there to the mechanical pump on the engine with an inline filter between the tank and the pump. Another option is to add an swecong bung to the tank and cap the outlet in the event that you want to change the configuration of your fuel system later.

 

[DougnDog]

gas tank

Hey man
If your gas tank is higher or level with your carb (think parking on a hill) you should have a gas shutoff valve and use it. a must if drawing from the bottom of any tank. most gas tanks draw from the top to prevent sifening(sp) you could fill your engine with gas. I saw a engine that filled with gas after it blew when the guy tryed to start it . blew the valve covers half way through the hood. good luck
Doug

 

[Ratcrazy]

Hey man
If your gas tank is higher or level with your carb (think parking on a hill) you should have a gas shutoff valve and use it. a must if drawing from the bottom of any tank. most gas tanks draw from the top to prevent sifening(sp) you could fill your engine with gas. I saw a engine that filled with gas after it blew when the guy tryed to start it . blew the valve covers half way through the hood. good luck
Doug

Doug is correct, please use the shut-off valve if you are mounting it up high.
Heres a few pic so you can see what we mean.
1] Tank with side site tube
2] Fuel shutoff valve
3] Parts for vented fuel spout (cap has small vent hole drilled in it a upward position to allow the tank to breath without fuel being spilled out)
4] Assembled fuel spout

Good luck with your tank.

 

[Bonehead]

I didn't even think of that, I guess cause mine is lower.

 

[kelseydum]

So your saying that if parked where my front end was lower than my rear that the gas would want to flow to the carb? The shut off valve seems pretty simple. I also think I'll add the second fitting and cap it like Gastrick said.

Thanks for the replies. I know it sounds stupid but at least I know now. I could have someone build it for me ( I'll probably drill the holes and I WILL have someone do the welding for me) but I still want to know how everything works.

 

[Lightning]

Hey man
If your gas tank is higher or level with your carb (think parking on a hill) you should have a gas shutoff valve and use it. a must if drawing from the bottom of any tank. most gas tanks draw from the top to prevent sifening(sp) you could fill your engine with gas. I saw a engine that filled with gas after it blew when the guy tryed to start it . blew the valve covers half way through the hood. good luck
Doug

Then how do the motorcycles get away with it? As long as your float and needle and seat are working right no worries - BUT if not you could fill the crank case - - Better safe than sorry.

 

[Tripper]

Hey man
If your gas tank is higher or level with your carb (think parking on a hill) you should have a gas shutoff valve and use it. a must if drawing from the bottom of any tank. most gas tanks draw from the top to prevent sifening(sp) you could fill your engine with gas. I saw a engine that filled with gas after it blew when the guy tryed to start it . blew the valve covers half way through the hood. good luck!

Yep... this happened to the Daytripper. My gas tank is higher than the carb & one time I guess the float stuck & filled the motor with gas. After a messy oil/gas change... I installed a shutoff valve & use it every time. Guess it's also a security device!

BoB

 

[wildcat]

guy i was talkin to asked if i ever had a siphoning problem on my car,i never had .after reading this info ill be installing a shut off valve..thanks for the info.

 

[kelseydum]

Good, I guess this thread was helpful to more than one person.

I was taking apart a motorcycle the other day to get ready for paint. When I was trying to disconnect the tank I had it flipped hlf way over and started smelling gas. Turned it right side up and noticed gas was all over my pants. I thought for sure motorcycles would be sealed. What happens if they tip one over? That seems more likely to lay a bike over than flipping a truck.

 

[Lightning]

All of your m/c tanks have some form of breathing, mostly through one of the caps, on a split tank system, H.D.'s, it's the right tank and tanks with a single cap are vented through that cap. The Tripper is right about the shutoff valve, it can be a theft deterent, but also a pain if you forget to turn it on and motor down the road till it runs out, a m/c pet-co*k will usually have a reserve on it. But I always forget to turn mine off - - Thank goodness for a good working needle & seat and float.

 

[kelseydum]

Will these work for my hose fittings?... and what size?... 3/8 or do I need something larger?

http://www.speedwaymotors.com/Female-Aluminum-Weld-Bung-Fittings,7066.html

 

[Rev Tex Devlle]

as a former harley mechanic! most motorcycles today have a vaccum activated petcock valve! if you could incorperate thaT INT YOUR DESIGN, YOU WOULDNT HAVE TO REMEMBER TO CUT IT ON AND OFF!

 

[Lightning]

That's one heck of a good idea Rev. but I wouldn't know how to go about setting it up. My '99 is still a new item to me - not like my pan or shovel. I would think that the 1/4" at the smallest would be just fine - something the same size as for a regular fuel line or maybe larger if ya plan on running a blown bb w/ ele. fuel pump.

 

[dmw56]

Will these work for my hose fittings?... and what size?... 3/8 or do I need something larger?

http://www.speedwaymotors.com/Female-Aluminum-Weld-Bung-Fittings,7066.html

Should work fine. Go with 3/8".

 

[kelseydum]

Well, I found out that my keg is stainless steel after all. So after I exchange my BS I bought from Speedway I guess I need to find a stainless filler neck. Someone mentioned it here in the thread. Is there anything under a bujillion dollars?

 

[Blue Eyed Devil]

You can TIG weld mild steel to stainless very easily. I have put many a mild steel NPT flange onto stainless kegs. There should be a shop near you that can handle the task...

 

[kelseydum]

So use stainless filler rod to do the welding?... or mild steel filler rod?

Also the guy that gonna do the welding for me has a custom bike shop and was talking about the petcock idea. The only issue we saw was the largest outlet we could find was 5/16. Would that be enough volume?