150 mercury speedo

[championandy]

I have an '84 Mercury Black Max 150. Since I bought the boat 2 yrs ago the speedo hasnt been working at all. I have a pretty good understanding of how the speedometer works. I am a little unclear as far as the pickup goes. I am assuming that the pickup hole is the small teardrop shaped hole in the leading edge of the lower unit. I have located the line that goes from the lower unit to the speedometer in the dash. I took the line apart at a splice about midway up the motor and blew air in it. It is unobstructed and the speedometer will move with air pressure applied. From the splice down to the lower unit is where I am confused. I took the lower unit off and the tube is not connected to the hole I asssumed was the pickup. It is attached to a threaded nylon fitting that screws down into the lower unit. What am i missing here? What is this fitting for? Is something hooked up incorrectly?

 

[championandy]

Re: 150 mercury speedo

Here are a couple of pictures of what I am looking at. The first is the nylon fitting that the hose is attached to. The second is the teardrop shaped hole that I am assuming is the pickup for the speedometer.

 

[jebeebe]

Re: 150 mercury speedo

That fitting is the one the tube should be hooked to. As for the teardrop shaped hole????????????? I had a 150 black max and the hole for it was a tiny pin sized hole in the leading edge of the sharp v above the gear case. These will often become pluged with wood from hitting rotten logs, "in my part of the country", or weeds. If you blow air in the tube and it comes out the hole youre talking about, it must be the one.

 

[championandy]

Re: 150 mercury speedo

thanks friend. I was looking at the wrong hole. found the tiny hole in the leading edge. used a small drill bit to clean it out. thanks for the advice.