Mercury 850 85 hp

[bicklebok]

Hello everyone. A friend of mine just bought an 850 series 85 hp boat. We are having a hard time finding information on it. Any help is appreciated. We are trying to troubleshoot it to get it running.

 

[Texasmark]

You are at the tip of the iceberg. Usually you start with fuel or fire then chase which one isn't responding.

 

[jimmbo]

Merc 850 could be a 6 cylinder from the 60s or a 4 cylinder from 1973 - 1977
It takes three things to make an engine run, Compression, Fuel, and Spark. remove any one and it won't run. First thing is check compression, if the engine is in poor mechanical shape, you may wasting time and money. Next would be spark, easy enough to check for. If that is there then proceed with the fuel system. Is fuel getting to the carb?

 

[Texasmark]

Mine was the 4 cyl direct charged.

 

[bicklebok]

Thanks for the tips guys. Im pretty familiar with what it takes to get an engine to run. We have already checked compression. We're getting spark and we can make it run by temporarily pumping fuel to the carbs. We have a fuel problem, and being I have never had to work on an outboard Im not sure if this engine has a mechanical fuel pump or an electric fuel pump because we found an electric fuel pump laying in the boat. (You know the scenerio-previous owner tried to jack leg a fix)

I think what we could use help with the most please is a good manual to purchase for this engine and a few tips on what fuel delivery system it is SUPPOSED to have.

Oh, and it's a 4 cylinder. It's on a 92 Maxum bow rider. Not sure, but it may be the original engine.

Thanks!

 

[Chris1956]

That motor is likely from the 70s. See if she has twin triangle-shaped fuel pumps and a distributor. Alternatively she could have a single figure-8 shaped fuel pump and 4 coil ignition. Of course, the serial number will pinpoint the year exactly.

It sounds like your fuel pump is faulty. Rebuild kits are cheap and easy to install.

 

[bicklebok]

Thank you Chris. My neighbor is having serious marital problems so we havent looked at it in a few days. Meanwhile Im trying to get my own boat going. Its an IO mercruiser 5.0

Hopefully he and I can work on his boat once the dust settles with his wife. Thanks again Chris!