Fuel line size

[staying alive]

having a problem finding out what size my 1994 Honda 9.9 fuel line should be .
It likes to stall at low rpm after doing some google reading one guy says that with a 3/8 fuel line and a long draw the diaphragm type fuel pump has a hard time pulling the fuel especially at low Rpm , it’s heavier the larger the diameter of the line
I have it plumbed to my main tanks and through the water separator so maybe he’s right but can’t find any specs on what it should be
Will 1/4 inch work????
Any opinions
It’s an old motor but I’m stubborn ( not smart ) and have basically replaced every part other than the prop
Trying get this thing to work right

 

[gungadin]

I would think that the easiest way to test your engine would be to eliminate your present fuel line altogether. Use a small auxiliary tank and plumb it to your Honda. If it runs fine, then use the plumbing you fitted to the small tank and plumb it to your main tank. If it still stalls the your problem lies within your Honda. A 1/4" line would be fine for a small engine like that.

 

[staying alive]

Good idea thanks

 

[fish brain]

Have you serviced your carb lately? Take it apart and blow some carb cleaner though all the ports, paying attention to the low idle pickup port. If there is a chunk of debris in there just running seafoam or some other solvent cleaner wont fix it.
I bet thats your problem.

 

[staying alive]

But a brand new Honda carb on it last year still got the issue

 

[Viking]

If the pump is mechanically driven off the cam or push rod. either could be worn. (not enough stroke = low flow). Just thinking outside the box of basics.
Ive had problems with those barbed check valves on the tank too.
Could be sucking air, put a clear piece of clear tubing inline on the suction side as close to pump as possible, and look for bubbles.

 

[bigdogg1]

having a problem finding out what size my 1994 Honda 9.9 fuel line should be .
It likes to stall at low rpm after doing some google reading one guy says that with a 3/8 fuel line and a long draw the diaphragm type fuel pump has a hard time pulling the fuel especially at low Rpm , it’s heavier the larger the diameter of the line
I have it plumbed to my main tanks and through the water separator so maybe he’s right but can’t find any specs on what it should be
Will 1/4 inch work????
Any opinions
It’s an old motor but I’m stubborn ( not smart ) and have basically replaced every part other than the prop
Trying get this thing to work right

Are you able to shut off the fuel supply to the main power? I had the same setup running off a built in tank and found that it ran fine on a day tank. I was advised to put in a shut off valve to the main which I did and the 9.9 has ran fine ever since.

 

[staying alive]

Thanks big dog that’s a good tip.
Couldn’t handle the uncertainty anymore bought a 05 Honda 9.9 with 100 hrs on it —1400.

 

[fish brain]

Thanks big dog that’s a good tip.
Couldn’t handle the uncertainty anymore bought a 05 Honda 9.9 with 100 hrs on it —1400.

Ah good, problem solved then!....