How to Change a Fuel Filter in a Mercury 150hp FourStroke Outboard

[@longwinterfallout]

Clear concise instruction, excellent bud!

[@doodlesmcshipshow1814]

I pulled the fuel filter out and there looks like there was an o-ring under it. The o-rings was broken. I can’t find the part number or size for it. Any ideas? Great videos by the way!

[@QuicksilverProducts]

The fuel filter used on the 150hp FourStroke is part number 879885Q. It does not contain any O-rings. If you've discovered a broken or loose O-ring, it is likely from inside the quick connection fitting on one of the fuel lines that connect to the filter. For those part numbers or component breakdowns, we'd recommend connecting with your Mercury Marine dealer or Mercury Marine product support. Contact details can be found via the link below. Thank you! 🔗: www.mercurymarine.com/us/en/about-us/contact-us

[@MooneysExcavating]

I have a 150hp identical and it recently started stuttering intermittently. I went to change this fuel filter thinking this might be the problem. I wanted to make sure it was getting fuel so I removed the fuel filter, set the hose off to the side, and turn the ignition to on, no gas comes out at all, how is the motor running if no fuel is coming out of either of these lines?

[@QuicksilverProducts]

The fuel lines leading to the filter and from the filter to the Fuel Supply Module (FSM) are low pressure fuel lines. When the key is on or the engine is running, a lift pump within the FSM pulls fuel from the boat's fuel tank through those lines and that filter. Fuel is then stored within the FSM where another pump, the high pressure pump, pressurizes that fuel and feeds it to the fuel rail on the engine. You did not have fuel flowing through the disconnected lines because there was no vacuum to pull the fuel from the tank, and the engine was running because there is stored fuel within the FSM available for the high pressure pump to use for the engine. If you let the engine run long enough, that fuel will get used up, and the engine will stop running. Think of the FSM similar to how a toilet tank works. There is a float inside, and the lift pump runs until enough fuel is pulled into the FSM and the float rises. Once the float rises, the lift pump shuts off, all the while the high pressure pump within the FSM is pressurizing that fuel for the engine. When the high pressure pump uses enough fuel that the float drops, the lift pump turns on again, pulling more fuel into the FSM.

[@Quad4Fun1]

What year is your 150, and what did you find was the cause of the stuttering? Thanks a bunch, troubleshooting ours at the moment.

[@MooneysExcavating]

@@Quad4Fun1still trying to figure it out. Just bought coils so going to try that. Did you figure it out?

[@ryanwalters4638]

What do you do when the lower hose goes back down into the hole!

[@QuicksilverProducts]

Sometimes it's possible to find and grab the fuel line through the opening with a needle nose pliers or a flexible-reach grabber tool. In extreme cases, the lower cowling will need to be removed.

[@mcplutt]

Dont't let it go back down the hole....

[@brentunruh9313]

How do you retrieve the bottom hose if you accidentally drop it?

[@QuicksilverProducts]

Generally speaking, if the hose falls through the hole in the adapter plate, you can retrieve it with a long needle nose pliers or tool made for grabbing small objects. In extreme cases where the hose cannot be accessed, the lower cowling of the engine must be removed.