Motor won't go past 5 mph

[scottgrissom]

Hola,

I'm having a problem with my 1984 150hp Mariner. The boat ran fine a few weeks ago, but last time I took it out I couldn't get up on plane. Its a big motor the size of my boat (18ft Wellcraft) and I even made everyone jump in the water to see if weight was the issue. The gas is probably 2 or 3 months old and I know that I accidentally put too much oil in the gas. Its a 50:1 ratio, but it running rich.

The motor starts fine and idle nice, but as soon as I push the throtle down it gets bogged down, but it doesn't die, just goes really slow.

Any suggestion? Thanks

Scott

 

[Windykid]

Re: Motor won't go past 5 mph

Check condition of spark plugs.

Perform a compression test.

Check for water in fuel.

Is the tank venting?

Is the hull full of water?

 

[Windykid]

Re: Motor won't go past 5 mph

Also try squeezing the bulb when this happens.

 

[scottgrissom]

Re: Motor won't go past 5 mph

The hull is solid and doesn't soak up water.

The belly tank was recently installed shouldn't have any water in it. I will put some water remover in it though.

I need to check the spark plugs and compression, but I had its yearly maintenence done not too long ago.

The tank is venting and the bulb is tight.


Also, when I first took it out that day it did get on step and seemed to be running fine. Then it seemed like I hit a stump and so I slowed down and never could get it going fast again. Sorry, that probably could have been useful at first. I didn't think much of it at the time.

 

[jsalter911]

Re: Motor won't go past 5 mph

I Have A 60 Hp Mariner Doing The Same Thing And I Found Out 1 Plug Was Not Firing And Bought A New COIL To See If That Is Problem. It Might Be The Switch Box But Check To See If All Plugs Are Firing,PROABLY DROPPED A CYLINDER

 

[scottgrissom]

Re: Motor won't go past 5 mph

Thanks for the responses. I'll take a look at the spark plugs and check out the compression.