40 mercury slows when given throttle

[blasep]

I have an 85 40 hp mercury 2-stroke. It ran good for a few months. Now it idles fine but when I put it in gear it sputters and barely moves the boat. I thought it was the fuel so I changes out the fuel and filters. Then I discovered if I go back and push on the motor while the throttle is open it goes, if I let go it stops. It continues to do this. Any help would be appreciated I am pretty new at this. also there is a little bit of water coming out just above the lower unit I didnt know if that was normal....thanks

 

[JAG59]

Re: 40 mercury slows when given throttle

Is the water coming out of some small holes? And does it look like it comes out in a mist or small stream from each hole? If so, that is a good thing. This is were the cooling water that circulates through the engine is discharged. I've heard it refered to as the pee hole or tell-tale hole. Viewing the water coming out insures that your water pump is working and that your engine should be cooling.
What do you mena by pushing on the motor?
I'm not sure what you mean and I don't want ot speculate without more info.

 

[blasep]

Re: 40 mercury slows when given throttle

Its the the tell tale hole water is coming out of there fine. It is like a mist spitting out but it is right above the lower unit. where the lower unit joins with the top. I mean by actually physically pushing (or pulling) on the motor itself, while someone else is driving. As I am pushing or pulling it seems to run fine.

 

[JAG59]

Re: 40 mercury slows when given throttle

Now I'm wondering if the water you are seeing is a leak, either in a seal or in the tube that carries the water from the impeller to the power head. As far as the sputtering, it is still hard to tell what it can be without more information. I would start by checking for spark at both cylinders. Another thought is a possible bad head gasket. This may explain the water you are seeing. It may be leaking out around the head, running down the block, and showing up where you see it. Pull the spark plugs and check for water in the cylinders. I've read it before. Now I'm going to say it. The best place to start with outboard repair is with a repair manual. Make sure you get one specific to your brand, model, and year. Also, you are a braver man than me to get behind a runnig outbord and push. I hear that props bite.

 

[blasep]

Re: 40 mercury slows when given throttle

thanks for the reply, I havent had a chance to try anything yet except reroute the throttle and shift cables, they were getting bound up, but it did not make a difference. I dont see any water in the plugs or running down anywhere? It's frustrating because I can really only tell if it is doing this while the boat is in the water...sorry for the lack of info, this is my first outboard and im pretty clueless

 

[Texasmark]

Re: 40 mercury slows when given throttle

Go and look at catalog pictures of engines running on boats while underway. You'll see where the water comes out.

Binding cables sounds like the right answer for your pushing on the engine to get it to run problem.

Glad you discovered that.

Mark

 

[roscoe]

Re: 40 mercury slows when given throttle

Check all fuel lines on the motor that connect to the fuel pump, from the fuel pump to the carbs, and the any other fuel line you can find.

Bend them a little, looking for cracks.
Replace them if you find a crack or split.

Also, check all exposed wiring for loose connections, missing insulation, or places where they may be pinched in something.

 

[roscoe]

Re: 40 mercury slows when given throttle

Also check the tower shaft that connects the carbs to the spark advance.

 

[829]

Re: 40 mercury slows when given throttle

I had a similar issue and it turned out I had a break in 2 of my spark plug coil wires. The shop fixed them am I am back up and running.