Mercury Black Max 175 hp

[altenhoffl]

I have a Mercury Black Max 175hp on a 23 foot 1989 Monza boat. I recently took the boat out and it ran fine going out but coming back it the motor acted like it did not want to run. I do have a 90 gal tank and had to put 28 gallons in to fill it up. The fuel already in it was 50:1 mix and I think I may have put too much oil in it or the previous fuel had a little too much oil in it as well. The motor does not want to stay running unless I idle up a little. My question to everyone is can you put too much oil in the gas to where it makes the boat want to not run?

 

[nbnewbie]

Re: Mercury Black Max 175 hp

I would imagine so, but i've never tried to see how high of a ratio it would take. I don't believe 50:1 would do it. You could check the spark plugs for signs of fouling. You might also try an external "test gas tank" mixed properly for your outboard and see if the problem goes away. You probably already know this, but at most any place that carries boat stuff, you can get a bottle graduated for ounces of oil per gallons of gas which makes accurate mixing very simple.

 

[j_martin]

Re: Mercury Black Max 175 hp

You could burn 25:1 all day. Maybe not idle all day, but running, it would just smoke a little.

Been there, done that. Had an oil alarm wig out on a full tank of fuel, long ways from ramp. Added oil to get 50:1 in the main fuel tank. Oiler, of course, was working also.

It was a little smokey, but it didn't even wreck a set of plugs. Had some of "those" looks when I was idling it at the ramp troubleshooting.

You probably are in need of a thorough tune-up, maybe agravated by a little water or dirt in the fuel.

hope it helps
John

 

[CharlieB]

Re: Mercury Black Max 175 hp

How old is the fuel before adding the new fuel? Did you have stabilizer in the old fuel?

Are you using a water seperating fuel filter?

 

[altenhoffl]

Re: Mercury Black Max 175 hp

That's what I thought of doing, the external gas tank test. Hopefully it does go away. Thank you.

 

[altenhoffl]

Re: Mercury Black Max 175 hp

The last time the boat went out was in SEpt and it had the stabilizer in it. Yes, we have a water seperating fuel filter.