Nitro won't get on plane

[steve stubblefield]

Hello all. This is my first post. I greatly appreciate any advice or info that you all may have to offer. Here's the situation. I have a 1993 75 hp 3 cylinder (2 stroke) Mercury on my 17' Nitro bass boat and the outbaord will not generate enough power to get the boat on plane. This first happened in 12/04 and I did the following to remedy the situation; pulled out the gas tank and cleaned it, rebuilt the carbs, changed the fuel filter, changed the plugs. Once everything was back together the boat started fine and idled fine. I seated the idle mixture screw on the carbs and backed them out 1-1/2 turns per the Clymer manual. I used the Clymer manual as a guide for all of this work and I feel confident that it was done correctly. However, something is still amiss. I tried to take the boat out this weekend and it only bogs down when I try to throttle up on plane. There is no missing, no backfiring, no surging, the boat just bogs. I have made the following assumption; if it was the fuel pump, the boat would at least surge forward until it used all the gas out of the bowls and then it would start to miss.....this doesn't happen. Please note that the stator on the boat was replaced in 1/04 and the boat operated fine all summer leading up to this recent occurence. A local dealer stated that there is a low idle charge coil on the stator and a high idle charge coil. Could the boat not be getting the electrical signals that it needs for high rpm operation? Thanks for the help.

 

[Silvertip]

Re: Nitro won't get on plane

All engine performance problems should start with compression and spark tests. Does the engine idle smoothly? Are you sure all cylinders are firing? Try giving the primer bulb a squeeze or two when the engine bogs. If it tends to pick up that says carb or fuel pump problem. When you rebuilt the carbs, were they taken completely apart and every passage inspected, thoroughly cleaned, and blown out with compressed air. It sounds like you have one or more high speed passages clogged.

 

[JB]

Re: Nitro won't get on plane

Hi Steve,<br /><br />Welcome to iboats. <br /><br />You have a Merc Troubles question.<br /><br />Going there.

 

[lmoreau]

Re: Nitro won't get on plane

Don't doubt that fuel pump! Mine used to just bog when you stomped on it...it's not like the engine would rev up to full and just not plane..it was just a bogging..like all air and no fuel...opened up my fuel pump and the diaphrams were all stretched out and had pinholes in them. Changed them all, boat runs fine now. If it's never been changed, prolly time to do it. It's only like 10 bucks for the kit!