88 Evinrude SPL - What Size fuel lines?

[ShawnQ]

Hello all.<br /><br />I am re-installing my engine after pulling it off to apply durabak to my boat. I had fuel/air problems prior to pulling the engine, and I need to replace my fuel lines.<br /><br />My original line was 3/8" from the tank to the primer bulb, and 5/16" from the bulb to the engine.<br /><br />Is it normal for the hoses to be 2 different sizes? and if so, should I just purchase the same size hose?<br /><br />Thanks<br />Shawn

 

[rickdb1boat]

Re: 88 Evinrude SPL - What Size fuel lines?

Shawn<br /><br />I would use 5/16" hose all the way. Should all be one size....Both sides of the bulb fittings will be the same size.......

 

[red boat]

Re: 88 Evinrude SPL - What Size fuel lines?

Rick, I was always told 5/16" for 3 cyl and below and 3/8" for V4 and above.

 

[ShawnQ]

Re: 88 Evinrude SPL - What Size fuel lines?

What happens if the fuel line is too large? Can you have overkill?<br /><br />Or is it better to go a bit larger than a bit too small, like on wiring?<br /><br />I would think that larger fuel line would put more pressure on the fuel pump because it has to pull harder to move more volume. I would also think that the smaller diameter would allow faster fuel delivery, just not as much.<br /><br />Any more thoughts?<br /><br />What happens if there is excess fuel in these systems? There isn't a return. Does the pump only work when the bowl needs more fuel, or is it continuous?<br /><br />SQ

 

[red boat]

Re: 88 Evinrude SPL - What Size fuel lines?

There is no problem using 3/8" fuel line. It does not put any pressure on the fuel pump the fuel pump only draws/sucks what it needs. The smaller fuel line does no allow enough flow thru it at WOT to feed a thirsty outboard so the fuel delivery is not fast enough to keep up with the demand. A smaller fuel line actually slows fuel delivery because it cannot get enough volume thru it. The flow of fuel into the carbs is controlled by the float/needle in the bowl. The fuel pump only puts up a maximum of approx. 8psi.

 

[ShawnQ]

Re: 88 Evinrude SPL - What Size fuel lines?

Thanks for the info red boat. I'll go with 3/8", better to have too much than too little.<br /><br />SQ

 

[rickdb1boat]

Re: 88 Evinrude SPL - What Size fuel lines?

Since the lines going into the carb on that motor are 5/16, I don't believe that a 3/8 is nessesary, as you can only put through as much as the smallest line will handle. But no harm in using 3/8 either...It is the V-6 that requires the 3/8 line...

 

[wilde1j]

Re: 88 Evinrude SPL - What Size fuel lines?

I had a J 140 '85 [V4] and it used 3/8' lines per the manual.