check valve on main motor and kicker question

I recently installed a kicker motor.

Main motor is a 1990 johnson 2 stroke vro, kicker is a 2004 tohatsu 5hp 4stroke

Current setup is

Fuel tank--> fuel water seperator --> one line to primer bulb to main, one line to primer bulb to kicker

i've noticed that when running my kicker, it would die out when i am on wot. Checking the primer bulb, it feel deflated, not firm with fuel. Checking my main primer, it is empty sometimes.

Does this mean that the fuel line on the main is emptying and air is going from the main to the kicker and thus starving the engine of fuel?

I thought adding the fuel water seperator is what avoids that? What can i do to ensure that both primer bulbs are full of gas when only operating one of the engines?

Would a check valve work? Has my primer bulb gone bad?

Thanks

Re: check valve on main motor and kicker question

Have you got a three way valve in the fuel system ??

Re: check valve on main motor and kicker question

No, its just fuel tank to fuel filter seperator and that has 2 fuel exits, so one runs to each one.

Re: check valve on main motor and kicker question

The fuel water separator does not prevent anything like that. There is a one way valve in each squeeze bulb, but they don't always work well. The arrow on the bulb should also point up for best results sometimes. Mine and all my friends have ours plumbed with no extra check valves or three way valves and have no problems.

Re: check valve on main motor and kicker question

I'm going to replace the older primer bulb and hope that it fixes it. It's possible the older primer bulb has a small backwards leak causing it to drain.

Re: check valve on main motor and kicker question

As pointed out, the best way to do this is with a fuel selector valve. If you don't do that, then make sure the primer bulbs are oriented vertically to give the check valves a better chance to work properly. Lastly, primer bulbs to not stay firm when an engine is running because fuel is being drawn through it. That system is not pressurized until after the fuel pump.