Fuel hose routing on 1993 Force 150

[HotTommy]

I'm replacing most of the rubber hoses on my 1993 Force 150 as I reassemble it. I'm using "before" photos and the FSM to get it right. But I find it helpful to understand how it is supposed to work. So here is how I think it is supposed to work. Please let me know if I've got any of it wrong.

• Fuel from the tank connects to the quick connect fitting on the front of the cowl.
• Fuel from the cowl fitting goes through the inlet hose to the fitting on the sediment bowl on the lower fuel pump.
• Fuel exits the lower fuel pump via the outlet fitting and the transfer hose.
• Fuel from the transfer hose goes into the fitting on the sediment bowl on the upper fuel pump.
• Fuel exists the upper fuel pump via the outlet fitting to the outlet hose.
• Fuel travels through the outlet hose into the T-fitting on the side of the bottom carburetor, where some fills the float bowl on the bottom carburetor.
• The rest of the fuel exits the T-fitting via the hose to the T-fitting on the middle carburetor.
• Fuel fills the float bowl on the middle carburetor and the rest exits via the T-fitting and hose to the top carburetor.
• Fuel fills the float bowl on the top carburetor.
• A fitting on the top carburetor float bowl allows some fuel to flow to the bottom (inlet) fitting on the Fuel Primer Valve.
• Fuel exits the Fuel Primer Valve during startup via the upper (outlet) fitting and hoses connected to the intake manifolds of each of the carburetors.

The Fuel Recirculation System on my engine had not been disassembled, so I will leave it as is. But I am curious about it's purpose. What does it do?

 

[pnwboat]

Re: Fuel hose routing on 1993 Force 150

Yes, your description of the fuel flow is correct. The fuel recirculation pulls any fuel that has puddled in certain areas of the engine block and feeds it to the intake ports of the cylinder to be burned off. It uses the pressure differential created in the by-pass ports and some one way check valves to do this. It helps to improve the low speed and idle characteristics of the motor.

 

[HotTommy]

Re: Fuel hose routing on 1993 Force 150

Thanks for the quick reply. ... I had forgotten that fuel for the 2-stroke goes inside the engine block on its way to the cylinders. It makes sense that some of it might not get to the cylinders directly and would need a way out.

 

[Frank Acampora]

Re: Fuel hose routing on 1993 Force 150

It is not that the fuel needs a way out: When puddled (condensed) fuel and oil accumulate to a great enough degree, a slug of it will enter the cylinder. This slug is too rich to fire so the cylinder misfires and the engine will stumble, stutter, and run rough. The recirculation system takes this puddled fuel and pumps it into another cylinder BEFORE it becomes great enough to cause a misfire (or recirculates it to the intake manifolds) and it is burned in that cylinder (or recycled) without mishap. This greatly improves idle characteristics.