1979 Mercury 40 hp issues

Maddoxsdaddy

Petty Officer 1st Class
Joined
Sep 22, 2008
Messages
222
Hi all. I've posted a couple of times on here w/very little response but i figured i'd give it one more try. This motor sat for approx. 5yrs before i got it. It is mounted on a 1981 Alumacraft 17'. At this point, the best speed i've gotten out of it is 15mph. It seems like it should do a bit more than that. Since purchase, i've replaced the stator, starter relay, re-wired everything, rebuilt the carb, rebuilt the fuel pump, replaced all water and fuel lines, new fuel tank, hose, bulb and fittings. The motor seems to want to "go" but hesitates and bogs down once i pass 3/4 throttle. I'm almost at my wits end and about to give up on this thing. The only thing in the fuel system that hasn't been replaced is the fitting where the tank to motor fuel line attaches to the motor.
I primed the motor this weekend to run it and noticed that fuel squirted out of something where the fuel line attaches to the motor but when i looked for where, it had stopped.
Could there be a leak in the fitting where the fuel line from the tank attaches to the fitting on the motor and could this be sucking air into the fuel line causing my whole problem???:confused:
Thanks in advance for any help.
MDSXDDY...
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: 1979 Mercury 40 hp issues

It sounds like a fuel problem, when underway pump the bulb if the engine pickup the you have a vacuum leak or the pump is no working properly. If that don't help either partly choke the engine at WOT or squirt some fuel in the carb throat if that makes it pickup RPM then the carb is still plugged somewhere. If neither thing helps you need to use a induction tach to see if it's running on both cyls. at speed.
 

ej-lakes

Recruit
Joined
Oct 27, 2008
Messages
4
Re: 1979 Mercury 40 hp issues

Alot of times when people get stuck in a rut on a project it so easy to just throw up the hands and say "forget it", but it always seems that if I take my time on trying to find answers, they'll come. projects like boats or 4x4's take time. So Im sure you'll figure it out over time. Best of luck, just don't sell the boat.
 

Maddoxsdaddy

Petty Officer 1st Class
Joined
Sep 22, 2008
Messages
222
Re: 1979 Mercury 40 hp issues

Thanks for the reply...
I've tried the choke and sprayed with carb cleaner before... motor almost cuts off. This weekend, i did notice that when i squeezed the bulb, it picked up but just a little bit. Nothing substantial...
 

Maddoxsdaddy

Petty Officer 1st Class
Joined
Sep 22, 2008
Messages
222
Re: 1979 Mercury 40 hp issues

Alot of times when people get stuck in a rut on a project it so easy to just throw up the hands and say "forget it", but it always seems that if I take my time on trying to find answers, they'll come. projects like boats or 4x4's take time. So Im sure you'll figure it out over time. Best of luck, just don't sell the boat.

I wasn't gonna get rid of the boat but i do have a 1996 50hp 4-stroke w/a tiller handle that's in need of work that i might put on there instead of the 40...
 
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