tank plumbing question
 

I am getting ready to install my first gas engine into a decathon that I am building and I am not sure how to plumb the tank up. Do I use a pressure vent line to a muffler? How do you set up the filler line?
thanks
Jeff

RE: tank plumbing question
 

Gas engines do not use a pressure line to the muffler

The vent line is just open to the atmosphere

RE: tank plumbing question
 

Is it ok to tee into the supply line from the tank to use as a filler line with a fuel dot? Or would this flood the engine like a glow engine?
thanks
Jeff

RE: tank plumbing question
 

It'll work to tee it. I just use a 3 line system, only takes a couple extra minutes to setup.

RE: tank plumbing question
 

You have to keep the end of the fill line plugged with something air tight

RE: tank plumbing question
 

Fuel will not flow through a gas carb until/unless a pressure pulse is gotten from the engine. A "T" in the fill line will not flood the carb like a glow engine.

RE: tank plumbing question
 

I prefer a 3 line system as well.

One to the fill line with a clunk (Gem Dots are awesome fuel dots btw)

One to the carb with an inline filter and a clunk.

One vented to the outside, usually under the cowl.

RE: tank plumbing question
 

Curious: Why the clunk in the fill line? Is it to enable defueling? Also, I like to loop the vent line back over the tank and then out the bottom to inhibit fuel spilling out the vent line when the AC is nose down.

Richard/Club SAITO 635

RE: tank plumbing question
 

To enable defueling

RE: tank plumbing question
 

I have been using the two line system with the Slimeline # 2610 Excel Fueler. This has a screw in cap with an "O" ring. Never had a problem with a leak, like with EZ Fuelers. I also use walbro in tank clunk and filter. Walbro part number 125-527-1. I had several engine outs using in line filters. They are small and if they get stuff in them, will slow fuel flow just enough for engine to lean out and quit. No problems since using the walbro. Also the walbro in tank filter is fuel soaked and if it comes out of fuel momemtarily, there is no interruption in fuel flow. I use thin wall tygon tubing inside the tank for flexibility. Available at Ace Hardware. Also solder barb to fuel pickup line in tank and tie wrap it. Otherwise IT WILL COME OFF, eventually, usually just after takeoff. Also I don't defuel the planes. I leave gas in the tank. This keeps the in tank fuel pickup line flexable. I use a short peice of plugged fuel line for a cap to the vent line when not running, keeps fuel from running out when handling the plane and prevents mosture in tank. I have not had any problems using this system. No engines out, no dirty carbs, erratic running, leaks etc. Only took me several years to do this correctly.

RE: tank plumbing question
 

The above post is the way to do it

RE: tank plumbing question
 

Zoom in on these PDF's. I made them for people who would ask for a diagram how to plumb a tank. You can leave off the inline filter if you want. It's personal preference. This at least gives an idea. Just don't leave off the barbs and zip ties. I personally use the 3 line. I'm always concerned my fuel dot will leak air. The three line can give you a straight shot to the carb if you leave off the inline filter....which I'll probably do on my next engine (DA-120).

And people, please please...I'm not criticizing anybody's method for plumbing a tank. There are many right ways. Mine is just one that I prefer.

RE: tank plumbing question
 

Joe A.P. thanks for putting that up!!!!

RE: tank plumbing question
 

Joe AP thanks. I'm putting my first gas engine. Electric was my choice in the past. My question is how far can tank be from carb? I have a great spot to install a larger tank but it is 8" from carb. It would also help move tank closer to center of plane. Any help or awnser!!! Installing a 20cc areovate in a Dave Platt T-28B select scale 65"wing span.

RE: tank plumbing question
 

A basic 2 line system still works fine. For some reason a great many people seem to believe that over complication improves performance. I've tried them all and complicated just isn't necessary.

One line from the tank to the carb, with a tee to a fill line. The fill line has to be plugged after filling and de-fueling. The de-fuel clunk is the same one used for fuel pick up when flying. The second line is the vent, usually routed out to the atmosphere under the bottom of the plane and left open. And no, there really isn't any large benefit to making a vent line loop over the gas tank....

One can pick up fuel dots and tees at any hobby shop. One dot, one tee, does the job. If a person is smart they install a filtered clunk on the end of the fuel pickup line inside the tank to handle all the filtering needs prior to the carb. The vast majority of hobby shop fuel filters are useless for gasoline. The one thing they do best is generate sales for the hobby shop. Rarely do they stop small particulates from reaching the carb.

RE: tank plumbing question
 

I always use a 3 line system with my gassers, but replace the klunk with a "walbro" pickup/filter as used in weedeaters or chainsaws. This stops air in the fuel line due to fuel foaming and is also a filter for the fuel.

Cheers

RE: tank plumbing question
 

That is how I setup my fuel systems with no loop over the tank except there needs to be a filter between the tee and the carb because I have no filter in the tank. If you fill your tank through the tee with a Walbro filtered clunk in the tank, the crud collects inside the Walbro filter and nice clean fuel goes into the tank. However, when you start your engine that same crud is sucked back out of the Walbro filter interior and goes into the carb.
I do have Walbro filter clunks on hand and if I use them I will have to provide another line to fill the tank so that the tank is not filled through the Walbro filter. My fuel jug is also filtered.

RE: tank plumbing question
 

This is why a second clunk filter is used on the pick up line from the fill can.