Fuel hose size

[Dirtyfuzz]

Had an Interesting issue with outboard today, new fuel tank is fitted and replaced all the fuel lines that were 5/16 with 3/8, motor sounded like it was starved of fuel and the primer bulb wouldn’t pump up, works fine on the reserve tank with 5/16 hose line, swapped out the primer bulbs same thing, reverted all the fuel lines back to 5/16, primer bulb pumps up and is now running fine, I wouldn’t have thought going a little bit bigger on the fuel line would make that much difference but I guess it must be enough pressure loss to cause issues!


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[catshark]

yeah i did that too at one stage , and resulted in a cough from the engine every now and then , whether that was a cause not too sure, but seem to run okay regardless. went back to 5/16 .

[Fed]

Sounds like you had an air leak with the 3/8 DF.

OMC V4s 5/16" minimum but 3/8" preferred.

[Dirtyfuzz]

Possible, I checked and retightened all fittings,new filters etc, with no affect, port motor still has 5/16 and has never had an issue which leads me to believe it’s the fuel line size that caused the problem, anyhow it’s fixed so am happy!


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[Dignity]

3/8 is pretty standard these days, air leaks would be the problem, you actually have increased volume of fuel available and 2 stokes certainly like to suck fuel so something else is the issue.

[scottar]

Wouldn't be the first time a new primer was dicky either.

[Dirtyfuzz]

Wouldn't be the first time a new primer was dicky either.

You were right! Made up a new reserve tank line using the 3/8 hoses and the new primer bulb, sceptor primer bulb is stuffed and sucking air in at clamp fitting!


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[Noelm]

I only ever use genuine primer bulbs, usually Yamaha because it's the closest to me, they also sell the other after market ones, and for the few dollars difference, the genuine ones are far superior.