Fuel flow 1993 Mariner 175

[mckinney004]

Situation/background: Recently purchased a 1993 Lund Baron 2100 GranSport with a 1993 Mariner 175 EFI Magnum serial# 0D188725 (not sure if that is a "O" or zero). That is an oil injected 2 stroke. Long story short, I bought the boat from an elderly man who purchased the boat, had it tuned up, then had a stroke before he could ever use it. The boat sat for 8 years before I purchased it a week ago. Now I'm trying to fire it up.

Analysis: Compression is good. Cylinders are lubed up. Spark to all 6 cylinders. I don't appear to be getting fuel to the cylinders. This is my first big outboard, first EFI, and first oil injected motor. I have quite a bit of experience working on older/smaller outboards. I have found a couple small fuel/oil lines that were dry rotted and broke when I touched them. None of them are release much, if any, fuel when I crank the engine.

Request: Can anyone explain or point me in the right direction about the path of fuel from the fuel line connection to the cylinders? I also plan to disable the oil injection, and premix my oil/fuel. Is there a way to rig that by simply blocking oil lines, or does it REQUIRE actually removing/replacing parts. I'd prefer to just block off the oil supply and pull fuel+oil through my main fuel line if possible. I would remove/replace parts if required though.

Thanks everyone in advance.

 

[GA_Boater]

Fuel line connector ->Fuel Pump-> Injectors.

If you go with pre-mix, you're gonna be back with a new thread - "My Motor Just Blew UP - Why"

This motor isn't like a carbed 2 stroke. Oil injection lubes the motor, not a mixture of gas and oil.

 

[Dukedog]

This motor isn't like a carbed 2 stroke. Oil injection lubes the motor, not a mixture of gas and oil.

but you made an oops here..efi mixes oil and fuel in tha vst prior ta tha injectors..carb does it at mechanical fuel pump.. tha optimax (opti) is tha only merc 2 stroke that doesn't mix it....

 

[Dukedog]

McKinney 004, its a "0".. if ya send me an email address i'll send ya an OEM manual that has your motor in it.. almost any merc parts olace will have a "block off kit" for you oiler delete.. several on here that can guide ya thru it if you decide ta do it.. knowing tha parts description helps a lot.. that's where tha manual will help ya a lot.

motor set that long your gonna be a busy guy for awhile.. lotta things need replacin' and/or cleaned...

 

[mckinney004]

UPDATE: She runs like a top! Big shout-out to Dukedog for the service manual so I could easily trace the fuel path.
The broken lines were minor oil lines that shouldn't have affected fuel flow. After a false positive checking the fuel pressure at the schrader valve, I realized there was a blockage in the vapor separator. Mechanical fuel pump was pumping through the fuel filter and back to the vapor separator, but no fuel was coming out the exit and on to the electric fuel pump and so on. Took VS apart and found blockage/ stuck float/needle. Once that was cleared and primed, I was able to get actual fuel pressure at the schrader valve. Previously, I was getting 40 psi, but after releasing pressure a few times, I was no longer getting fuel. Now I consistently get 40 psi with constant fuel supply. Cranked the engine and she fired right up.

NOW: The oiler delete/block off kit... Where's the best/cheapest place to get the parts? Where's the best info for installing it? I didn't see it mentioned in the service manual, but I could have missed it. Thanks again for the help everyone. Cant wait to get this thing out on the water!

 

[mckinney004]

GA_Boater It sounds to me like you're referring to more of a 4 stroke setup or something else I'm not familiar with. This is a 2 stroke with oil injection that mixes with fuel in the VST before reaching any internal parts. It seems to me that blocking oil supply and pulling pre-mixed fuel should not cause any overheating/lubrication issues that could damage the motor. Can you confirm?

 

[GA_Boater]

You manual should have a write up on the workings of the oil injection. I didn't have one in front of me.