Fuel setup two outboards, one tank.

[Rranger]

I probably have the answer but will ask. I have a merc 125hp and Honda 9.9 kicker coming off one fuel tank with one line into a fuel/water separator and one line out to a primer bulb then tee'd to a 5/16 line to the kicker and 3/8 line to the 115 HP. My kicker stalled a couple times last time out, thinking its losing prime with present setup. So do I tee off before my separator and run a new separator for the kicker and use the present separator for the 115HP. And should I plumb in fuel filters after the separators, or are they all I need?

 

[Chris1956]

One separator is fine. You need a selector valve to keep the fuel line in use, from sucking air, from the other motor.

 

[roscoe]

one line tank to separator
2 lines out of separator , each with it own primer bulb

 

[Rranger]

one line tank to separator
2 lines out of separator , each with it own primer bulb

I have run my 5/16" line from separator to my 9.9hp Honda and my 3/8" line to my Merc 125HP from separator. Both with primer bulbs. Do the primer bulbs have backflow preventors built in?

 

[roscoe]

Yes. Check valves in bulb, or the bulb would not pump.

 

[Chris1956]

Check valves in primer bulbs are usually worth about 2 cents. The check valves in the fuel pumps are much better. However, it could be that without shut off valves, one motor or the other will suck air from the other. Test is and see if the check valves are sufficient.

 

[Rranger]

Check valves in primer bulbs are usually worth about 2 cents. The check valves in the fuel pumps are much better. However, it could be that without shut off valves, one motor or the other will suck air from the other. Test is and see if the check valves are sufficient.

I guess we find out on the lake.

 

[guy48065]

In theory the check valves in 2 primer bulbs would isolate each carb from the other but I agree they are so cheap it might not work well.
BUT
In order for one carb to suck air from the other it would need to pull the inlet valve off the seat. That doesn't seem likely.

 

[Chris1956]

Gee, I can see a scenerio where you are running on the kicker for several hours. During that time the gas in the carbs of the big motor evaporates, lowering the float and exposing the inlet needle to the air in the carb bowl. Carb bowls are vented, which allows the kicker to suck air.

Now in order for that to happen, the check valves in the fuel pump and primer bulb need to allow fuel to drain to the tank. I have faith in the check valves into the fuel pump, but I would be interested in the POs real world test.

 

[guy48065]

Does that happen? My pontoon sits at my cottage for weeks between visits & the carbs never dry out.
A squeeze of the bulb when switching over might help insure all bowls are full for awhile.

 

[flashback]

Post #2 would be a simple mod and insure no air gets into the system from the other motor..

 

[Chris1956]

Guy, That probably works, in theory. to go further, I would expect that to work. Let's see if it does...
Maybe we are chasing wild geese.

 

[roscoe]

My set works for me. Possibly because the fuel tank and separating filter are on the same level. And possibly because my primer bulbs are positioned vertically ( arrow pointing up )..

If it doesn’t work for someone else, they can always pull the fuel line off the other motor as a temporary fix.

You’d think that if it was going to suck air from the other motor, that it would do it when primed the motor

 

[Rranger]

Will try the two separate lines off the separator with separate primer balls. if that gives me issues will go to the selector switch. Thanks for the input.