One fuel line to two engines

Ifishmuskie2 · 2026-02-26T11:10:21-0700

I searched for the answer but i can’t find it.
I have one fuel tank and one line coming out. I have a main and a kicker. I was thinking of installing a selector switch but then I have to switch it all the time. What about installing a filter with two outlets? Would that stop one engine from pulling fuel from the other? I don’t really need a water separator.

Scott Danforth · 2026-02-26T11:28:13-0700

Ifishmuskie2 said:
What about installing a filter with two outlets? Would that stop one engine from pulling fuel from the other?

nothing

its been discussed before. you actually end up drawing air in from the carb in the kicker and you basically run out of fuel on your main.

if you have a below deck fuel tank, there most likely is another location you can plumb in a pickup tube.

Ifishmuskie2 · 2026-02-26T11:41:32-0700

I don’t see another outlet on the below deck tank. So a selector switch is the best option?

Jeff J · 2026-02-26T12:02:45-0700

I think a primer bulb or some other check valve on each line coming from the filter would take care of sucking air through the other engine.

Mc Tool · 2026-02-26T12:04:00-0700

Scott Danforth said:
its been discussed before. you actually end up drawing air in from the carb in the kicker and you basically run out of fuel on your main.

Far out

I bet that has caused some serious head scratching for some peeps .

Jeff J · 2026-02-26T12:07:21-0700

A 3-way valve on the filter outlet would take care of it too. Maybe that is what was meant by “selector switch”.

Scott Danforth · 2026-02-26T12:13:32-0700

Jeff J said:
I think a primer bulb or some other check valve on each line coming from the filter would take care of sucking air through the other engine.

you would think so, however it doesnt. also, a primer bulb on I/O's is not allowed.

the OP has two outboards. so it could work. the cheesy flap check in the primer bulbs work for a while to prevent issues, however can fail, especially if the main motor is an I/O

and a 3-way marine fuel selector valve is kind of pricey

Jeff J · 2026-02-26T12:24:08-0700

I always wondered why the I/Os in the fleet didn’t have a primer bulb. They sure come in helpful when a boat gets run out of fuel.

An on/off valve on each line maybe? But that brings us back to switching.

Ifishmuskie2 · 2026-02-26T12:41:23-0700

I guess the selector switch/valve. Is the best answer.
I fish with a friend and he’s always telling me to go back and turn the switch so I guess I’ll get the co pilot to switch it when I’m driving lol.

alldodge · 2026-02-26T13:13:43-0700

Might get 2 fuel vales and Tee them from the tank tube.
https://www.ebay.com/itm/143388702127?chn=ps&google_free_listing_action=view_item

A marine electric 3 way valve is around $800
https://www.hardin-marine.com/p-13899-3-port-superflow-fuel-selector-valve.aspx

Jeff J · 2026-02-26T14:49:39-0700

DANG! Even fuel valves for aircraft are not that high. Here I thought there is nothing more expensive than aviation.

Ifishmuskie2 · 2026-02-26T16:00:42-0700

A manual one is under $100

airshot · 2026-02-26T16:06:58-0700

Most small out boards have a quick connect right at the motor, so why not just unplug the fuel line when not using the kicker ? Years back I added a primer bulb to the fuel line on my I/O as it had a 10' long run to the tank. When I had my safety unspection, the inspectors saw it and said it was a good idea....never said a word about being illegal....

Ifishmuskie2 · 2026-02-26T18:52:42-0700

I could be switching from main to kicker ten times in a trip as I move to different spots.
That’s why I’m looking for the easiest way.

tphoyt · 2026-02-26T20:03:06-0700

If you went with your plan on using both outlets on the filter you could add an inline shut off to the kicker. Of course you would still need to turn that on and off each time but it’s quick and easy. If you have to add said filter may as well go with a water separator as every boat can benefit from that.
Just a thought.

roscoe · 2026-02-26T22:47:14-0700

I have been running a water sep filter with 2 outlets.
A primer bulb on both, going to a 115hp and a 15hp outboard.
Have never had one sucked dry of fuel. Even with running the 115 for
45 minutes, the kicker primer bulb stays full and always pops right off.
I use OEM rubber bulbs, and they are positioned vertically, so maybe that helps.

If I ever did have an issue, I knew I could always disconnect one fuel line from a motor.

Jeff J · 2026-02-27T08:38:49-0700

I have never really been around kicker motors. I am guessing the one in this case is big enough to have power tilt/trim hence the desire for switches. What I have seen were tiller control and manually tilted so having a manual selector wouldn’t matter.

Hanging the primer bulbs vertically is a very good idea for this situation. I have had several that would only pump up if held vertically. I had forgotten about them until I read that post.

Mc Tool · 2026-02-27T11:31:31-0700

Other possibilities
Vacuum operated fuel ****,
Or if your kicker has a charging coil use an electric fuel ****
Both are standard fitting to some motorbikes and quads so not hard to find .

Mc Tool · 2026-02-27T11:34:21-0700

Mc Tool said:
Other possibilities
Vacuum operated fuel ****,
Or if your kicker has a charging coil use an electric fuel ****
Both are standard fitting to some motorbikes and quads so not hard to find .

Oh FFS ! Its a fuel see oh see kay
A fuel "tap" for whoever is in charge of censorship

One fuel line to two engines

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