8 hp Honda fuel line help

I have a 4.3 mercruiser v6 main engine in a 19’ Bluewater, and I want to hook my kicker motor into the main fuel tank.

can I simply tee into the fuel line coming out of the tank and put an inline gas filter to my kicker fuel line? Or does there have to be a check valve in the new kicker line so as not to interrupt the gas flow to the main engine?

i really want to eleminate the portable fuel tank for the kicker. Kirk

I would T it off after the external fuel-water separator and install a primer bulb in-line, which will have a check valve inside.

Just my opinion since I've never tried doing this but yes, you would want to put a check valve in the add on line. Not to protect the main engine's fuel supply but to keep the fuel supply to the outboard in the line from being sucked out during main operation. These little pumps are not self priming.

Another problem I would anticipate with a set up like this would be if the outboard pump has enough suction to pull fuel from the main tank. While it may produce enough "suction head" to pull adequate volume from a full tank of fuel it may lack the power to pull from a tank that is lower on fuel. You may just have to try it to see how it works but there are formulas for calculating suction head on pumps that might be useful to you.

Like I said, never tried it. So, I will be interested to see what others here have to share on this.

Good luck.

Chawk_man has a very good idea.

After further thought though, I think that you may actually need 2 check valves in a "T" off the line to the main. One to protect the kicker supply and another to protect the main supply.

That makes chawk_man's idea even more interesting because, If done correctly, it might eliminate the need for a second check valve.

Good luck....again.

Thanks for the input guys.... that is why I’m asking .... common sense tells me some kind of a back check valve is going to be needed tying into the main fuel line off the tank.

But what I’m wondering is if I should just keep the primer bulb in the kicker line as one back check, and just move it outside the hull next to the motor connection for convenience , and put a second back check valve right after the tee connection into the main line. I’m not so sure those little back check valves built into the primer bulb with hold up to the pressure the main engines fuel pump will put on it.

My only concern is whether adding that second back check valve will put extra load on the kickers internal fuel pump. I’m just not familiar on how a fuel line back check valve works. Is is just a floating ball bearing? or a flipper valve?
i may just have to play with this.

typically the main engine won’t be running at the same time as the kicker, and therefore won’t be putting any back pressure on the line with the main engines fuel pump at all..... but.... I don’t want the kicker dying every time I fire up the main engine.... gotta have the back check valve.

Well it's not PRESSURE, per se, that you're guarding against. It's SUCTION and that makes it a much "smaller" force to deal with.

Yes, AFAIK most check valves in inexpensive primer bulbs are of the hinged door or flapper, as you say, with a very small spring to tension them normally closed in all but the most cheaply constructed . But I don't doubt that other type valves in primer bulbs are available.

It's my opinion that the standard type check valve can easily withstand the suction force of your fuel pump without collapsing but swing door check valves should always be oriented so that gravity can assist in keeping the valve closed. If the hinge is positioned on the bottom, the "door" tends to hang open.