boat will not plane MERC 150

[fivebites]

I have a 1987 Merc 150, the motor starts and runs fine. The problem: when I try to get the boat on plane the motor boggs down, it acts like it is flooded. I can put it in netural, rev it up for a few seconds, slam it in gear and then it will finally get on plane, or I can have somebody stand on the front deck of the boat and that works. I have replaced the stator, new power packs, carb rebuilt, new boysen reeds, timing is set, oil/gas mix is correct, replaced spark plugs, run 93 octane gas. Once its on plane the boat runs fine. Someone said something about the thermostats, and boring out the exhaust ports? Any suggestions and advice would be greatly appreciated. Thank You.

 

[Bear]

Re: boat will not plane MERC 150

Hi fivebites!<br />Carbs rebuilt, but did you check the float level?

 

[JB]

Re: boat will not plane MERC 150

What prop are you using?<br /><br />What rpm at top speed?

 

[fivebites]

Re: boat will not plane MERC 150

Thanks for the replys, boat runs 5500-6000rpms top end, have tried several props, I do not know about the float levels. Mechanic did all the work, hope he would know to do that. I forgot to mention that the boat does not do this all the time, if that makes a diffrence.

 

[rons boat]

Re: boat will not plane MERC 150

One of my best friends is a expert at marine carbrurators and it is his experience that your type of problem is usually a piece of trash in the carbs. A piece of gasket, a piece of anything will provide this off and on situation. He has taken the carbs off and on so many times and finally will find this hard to find obstruction. Admittly, it could be something else overlooked. You have my sympathy. Stay with it and if your mechanic will offer to help, demonstrate the problem to him.

 

[KIWI MERCMAN]

Re: boat will not plane MERC 150

Five Bites<br />Merc had some problems with their puddlke drain valves on that models and there was a service bulletin on it. They would block up and make the engine run like it had the choke on until it got going then it would run fine.<br />GO get them checked, it was a 86,87,88 bulletin.<br /><br />KIWI<br />RTFM

 

[KIWI MERCMAN]

Re: boat will not plane MERC 150

Five Bites<br />Sorry, Puddle drain valves

 

[AndyL]

Re: boat will not plane MERC 150

Try running in calm water with the cowling off and the carb cover removed. When the problem occurs check in the throats of the carbs and see if any are doing something strange. ie pouring neat fuel in. I had a problem years ago and finally traced it by doing this. It was an intermittent fault with the needle seat. Admittedly not on the same engine. If you find a problem you will at least know which carb to go for.

 

[Brew]

Re: boat will not plane MERC 150

I would caution you about running the motor with the carb cover off. With all the extra air being forced through the carbs, you could lean out the motor and fry a piston.<br /><br />My 2 cents.<br /><br />Good luck.

 

[mellowyellow]

Re: boat will not plane MERC 150

I agree with Bear, sticking float. tap on bowl<br />will sometimes free it up.<br />good luck,<br />M.Y.

 

[ronnieboy]

Re: boat will not plane MERC 150

try a ventilated prop, like my turbo 2+2 4 blade stainless, i use a 19 pitch, comes out great, loaded or unloaded, good luck ron