Fuel Line I.D.

[Beau Parsons]

I have asked this question to a few club members and thought I would ask more boaters there opinion. Does it make a difference to use large fuel line opposed to small fuel line inside dimensions ( I.D.)? Is there a golden rule to go larger I.D. with larger motors? And does it make any difference if you use a third channel needle valve? Obviously you can only flow as much fuel through a third channel needle so why go with large fuel line I.D. if the needle can only handle what the capacity it is designed for, why up size to a larger size fuel line I.D.? Any help would be greatly appreciated.

Thanks Beau Parsons

 

[P THOMAS]

Large size line should be used on bigger motors. Newer motors need lots of fuel. When the mac 67 came out it was nessasary for me to go to larger lines cause the engine could not get enough fuel. You may have problems if the line cannot deliver enough fuel to the needle valve to make the engine run at a rich setting. I even ran the small line direct to the carb, no needle, and it still ran a bit lean.

 

[anthony_marquart]

If you are running dual tanks it can help to run as large of fuel line as possible..

 

[TimothyJones]

If you are running dual tanks it can help to run as large of fuel line as possible..

Especially on the transfer line between them. Been There!!

More restriction requiers more pressure to achieve same volume.

On a needle valve, you want more volume going in that can go out.

Have you every had someone flush the toilette while you were in the shower, Kinda the same thing. More media is being drawn that can be supplied"for whatever reason it may be" Line size ,pressure......

 

[Ken Webb]

You guys are saying larger line. What size? I've some 3mm id, and some a little larger.

 

[TimothyJones]

The main reason I had to go larger 4-5mm/ 1/8" ID transferring between the tanks on my sport 40 was because of the length of line between the tanks.

At top end the boat would sag and rpm would fluctuate. Don F helped me with that, one day at the lake.

Previously on the 45 I had all 3/32" ID . Im sure the larger motors require something bigger.

 

[David Ashcroft]

I run 5/32" brass and fuel line on my tanks..

David

 

[jwo]

I run 3/16 ID stainless in tanks and 3/16 ID line. I wouldn't run anything less than 5/32 for a scale.