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Author Topic:   Mercury 200 EFI Fuel System

off the hook posted 12-25-2008 06:31 PM ET (US)
I have a Champion 20-foot bass boat with a Mercury 200 EFI. I am not getting any fuel through my primer bulb. I have replaced the bulb, as well as all the fuel lines. The system is air tight with no leaks at any connections. The primer bulb line goes from a brass distribution block located in the gas tank area to the motor. If I connect the line directly to the gas tank (bypassing the brass block) it pumps fuel fine and works flawless. Is this normal? Can I just bypass the block and run straight off the tank? From what I can see it appears as though the oil [mixes] at the engine and not prior, so I should not have any oiling concerns. Right? Any help would be greatly appreciated. Thanks
Dustin
jimh posted 12-25-2008 10:51 PM ET (US)
On most Mercury engine which have automatic mixing of the fuel and oil, the actual mixing of the two takes place under the engine cowling. You can find details of how the oil system works in an article in the REFERENCE section:
http://continuouswave.com/whaler/reference/mercuryOilInjection.html
From your narrative of the behavior of the fuel system, the malfunction does not appear to be in the primer bulb or the fuel lines. The malfunction appears to be in the "brass distribution block." Perhaps the "brass distribution block" contains a check valve intended to prevent siphoning, and perhaps this valve has become frozen.
An article in the REFERENCE section describes the operation of primer bulbs and how they can be used to diagnose problems:
http://continuouswave.com/whaler/reference/primer.html
off the hook posted 12-26-2008 12:00 AM ET (US)
Jimh, Thanks for all the info. I was looking at the first diagram and it appears that the oil mixes somewhere up inside the engine. I notice the oil lines on my boat go into the engine as well. Is this just an illusion? I am pretty sure that the brass unit is not working as well but am curious if there is a way to bypass it. It is located under the rear lid where the batteries and gas tank is. Thanks and I appreciate all the help. Also, where would I go to replace that brass unit? I am very new to this outboard thing and have only used inboard motors in the past.
Dustin
off the hook posted 12-26-2008 12:08 AM ET (US)
Jimh, I now understand what you mean by under the engine cowling. Sorry, I thought at first you meant under where the gas tank is. So could I rum my check ball line directly to my fuel tank to bypass the brass block? I am just trying to get the motor running for a tournament I have coming up. Thanks so much.
off the hook posted 12-27-2008 03:39 PM ET (US)
So can i run straight fuel through the primer bulb? Will the oil still mix under the engine cowl? Thanks
jimh posted 12-28-2008 11:56 AM ET (US)
Your direct question can't be answered because I don't have any idea of how your fuel system is currently configured. Many times previous owners make changes to the fuel system, including disconnecting provision which provide automatic oil mixing. You need to assess the configuration of your motor and fuel system to see if the original oil mixing system is still intact.
I also have no idea what a "brass distribution block" component in your fuel system might be. Perhaps it is crucial to your fuel system, but perhaps not. I can't tell. All I can tell is that when you bypass it, fuel flow resumes.
phatwhaler posted 12-28-2008 10:36 PM ET (US)
off the hook,
Not sure why you need a brass fuel manifold on a bass boat.
I would run fuel straight from the fuel tank to a "Mercury Quiksilver" fuel bulb, then straight to the lift pump on the engine.
You don't need a separate fuel filter/separator on a EFI engine. There should be a filter/sep already installed on the STBD side of the engine.
The oil enters the fuel inside of the aluminum tank mounted to the PORT side of the engine. There is a small clear hose that goes from the oil pump to the same aluminum tank on the port side.

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Author	Topic: Mercury 200 EFI Fuel System
off the hook	posted 12-25-2008 06:31 PM ET (US) I have a Champion 20-foot bass boat with a Mercury 200 EFI. I am not getting any fuel through my primer bulb. I have replaced the bulb, as well as all the fuel lines. The system is air tight with no leaks at any connections. The primer bulb line goes from a brass distribution block located in the gas tank area to the motor. If I connect the line directly to the gas tank (bypassing the brass block) it pumps fuel fine and works flawless. Is this normal? Can I just bypass the block and run straight off the tank? From what I can see it appears as though the oil [mixes] at the engine and not prior, so I should not have any oiling concerns. Right? Any help would be greatly appreciated. Thanks Dustin
jimh	posted 12-25-2008 10:51 PM ET (US) On most Mercury engine which have automatic mixing of the fuel and oil, the actual mixing of the two takes place under the engine cowling. You can find details of how the oil system works in an article in the REFERENCE section: http://continuouswave.com/whaler/reference/mercuryOilInjection.html From your narrative of the behavior of the fuel system, the malfunction does not appear to be in the primer bulb or the fuel lines. The malfunction appears to be in the "brass distribution block." Perhaps the "brass distribution block" contains a check valve intended to prevent siphoning, and perhaps this valve has become frozen. An article in the REFERENCE section describes the operation of primer bulbs and how they can be used to diagnose problems: http://continuouswave.com/whaler/reference/primer.html
off the hook	posted 12-26-2008 12:00 AM ET (US) Jimh, Thanks for all the info. I was looking at the first diagram and it appears that the oil mixes somewhere up inside the engine. I notice the oil lines on my boat go into the engine as well. Is this just an illusion? I am pretty sure that the brass unit is not working as well but am curious if there is a way to bypass it. It is located under the rear lid where the batteries and gas tank is. Thanks and I appreciate all the help. Also, where would I go to replace that brass unit? I am very new to this outboard thing and have only used inboard motors in the past. Dustin
off the hook	posted 12-26-2008 12:08 AM ET (US) Jimh, I now understand what you mean by under the engine cowling. Sorry, I thought at first you meant under where the gas tank is. So could I rum my check ball line directly to my fuel tank to bypass the brass block? I am just trying to get the motor running for a tournament I have coming up. Thanks so much.
off the hook	posted 12-27-2008 03:39 PM ET (US) So can i run straight fuel through the primer bulb? Will the oil still mix under the engine cowl? Thanks
jimh	posted 12-28-2008 11:56 AM ET (US) Your direct question can't be answered because I don't have any idea of how your fuel system is currently configured. Many times previous owners make changes to the fuel system, including disconnecting provision which provide automatic oil mixing. You need to assess the configuration of your motor and fuel system to see if the original oil mixing system is still intact. I also have no idea what a "brass distribution block" component in your fuel system might be. Perhaps it is crucial to your fuel system, but perhaps not. I can't tell. All I can tell is that when you bypass it, fuel flow resumes.
phatwhaler	posted 12-28-2008 10:36 PM ET (US) off the hook, Not sure why you need a brass fuel manifold on a bass boat. I would run fuel straight from the fuel tank to a "Mercury Quiksilver" fuel bulb, then straight to the lift pump on the engine. You don't need a separate fuel filter/separator on a EFI engine. There should be a filter/sep already installed on the STBD side of the engine. The oil enters the fuel inside of the aluminum tank mounted to the PORT side of the engine. There is a small clear hose that goes from the oil pump to the same aluminum tank on the port side.