Logo
FULL SITE MENU

Slow moving boat

T

Tarolo

New member
We just put a 1986 Mercury 50 hp 2 stroke outboard motor on a 1988 18 ft. pontoon that we repaired. When we took it out on water, it would go about 5-7 miles per hour. It sounded bogged down. My husband and brother in law tried some adjustments like adjusting the throttle cable but nothing helped. My brother in law was running a 55hp on his and he ran off and left us. He said it goes 15mph. What else could be causing the problem?
 
Could be many things. As simple as the vent not open on the fuel tank to a 1 or more faulty coils.
I hope you can find your problem
 
You need the proper prop for a pontoon basically a smaller prop that is heavily cupped for thrust it will never get up on a plane especially loaded down with weight.
 
The boat had a 15hp motor on it because it was just used on a private lake. Is there something we need to adjust since we changed it to a 50 hp motor?
 
Yes it is very likely way over propped to achieve proper WOT rpms. Get the part number off your prop and the width and pitch if possible. One of those timing light tachs will show you what rpm it is running at wide open throttle and then you size the prop from there. You want proper WOT rpms to extend service life of the motor. Lugging a two stroke will cut down its life considerably.
 
see what prop the brother in law is running...then try to find on the same size that fits your motor..
 
I've seen a similar problem on the same vintage motor, starts and idles fine but won't run much off idle. My problem was a bad stator. This is an easy check with an ohm meter. With a little hunting you can find the specs on line.

Tarolo said:
We just put a 1986 Mercury 50 hp 2 stroke outboard motor on a 1988 18 ft. pontoon that we repaired. When we took it out on water, it would go about 5-7 miles per hour. It sounded bogged down. My husband and brother in law tried some adjustments like adjusting the throttle cable but nothing helped. My brother in law was running a 55hp on his and he ran off and left us. He said it goes 15mph. What else could be causing the problem?
Click to expand...
 
Back
Top