1999 Mercury 115 ELPTO won't rev above ~2500 RPM

I just bought a boat with a 1999 115 ELPTO on it. I was not able to run the boat on the lake, etc. before purchase but did hook up the ear muffs and run the engine. It ran fine. Now that I've been able to get it out on the water, though, it won't rev above 2500 RPM when in gear. If I take it out of gear I can get it to rev to 5000-5500 but it smokes a lot and runs rought. If I put it back in gear it will not rev past 2500, which won't even get the boat on a plane.

This is a 2+2 engine I believe and I took the cowling off and had my daughter push the throttle handle all the way forward. It looks like there are two throttle cables coming to the motor but it looks like only one actuates. I can grab hold of the other one and pull it forward but I wasn't where I could run the engine (it was on the trailer with no water source for the ear muffs).

Is this the way these engines work and if the other throttle cable engages the other two carbs would it behave as I described, i.e. won't rev past 2500 under load and when in neutral smokes bad and runs rough.

Any guidance, ideas, suggestions would be welcome. I had the compression checked prior to purchase and all 4 cylinders checked out fine.

Thanks.

Re: 1999 Mercury 115 ELPTO won't rev above ~2500 RPM

Hi, Welcome to iBoats.

I would check the carbs, and have them cleaned.

A problem I had on one of my motors was the stator/alternator quit, so while there was a load on the engine, the battery alone wasnt able to provide enough spark to rev past about that 2500 point. new stator, runs like a top. just a thought.

Streffpilot

Re: 1999 Mercury 115 ELPTO won't rev above ~2500 RPM

Wow that sounds suspiciously familiar... Is there a way to test the stator/alternator? I'm brand new to outboatds (have always owned i/o's) so when I take the cowling off it's a bit intimidating under there.

Re: 1999 Mercury 115 ELPTO won't rev above ~2500 RPM

Yes, you will have to look up the specifics for your motor, but if it is a stator underneath the flywheel, you can use an electric multi-meeter to test the resistance (in Ohms) to determine if it is good or bad. on my motor (significantly older) the wires runing to the stator were dryrotted out, and needed to be replaced. someone else may be able to give you more specifics about your exact motor, but if you post a picture of your motor sans cowl, I may be able to give you a few ideas of what to look at.

Re: 1999 Mercury 115 ELPTO won't rev above ~2500 RPM

rlpatte said:

This is a 2+2 engine I believe and I took the cowling off and had my daughter push the throttle handle all the way forward. It looks like there are two throttle cables coming to the motor but it looks like only one actuates. I can grab hold of the other one and pull it forward but I wasn't where I could run the engine (it was on the trailer with no water source for the ear muffs).

Click to expand...

rlpatte,

I have a 97 model like yours and there is only one cable that is for the throttle. The second cable that you are referring to should be on a slide. If you slide it forward, it will go into forward gear, slide it backward and it will go into reverse. Working with that cable while the engine is running can be tough on the ankles. With the engine cover off, look at its location while in neutral, then push the throttle down and check it again. It should have slide forward about an inch.

hope this helps,
Brad

Re: 1999 Mercury 115 ELPTO won't rev above ~2500 RPM

Your ignition is not connected to the battery in any way, other than the ignition switch is actually TWO switches, one part a simple ground or no ground to allow the ignition system to work, and the rest of the switch connects power to acc's and cranks the starter.

The Ignition is self energized by the stator, the stator makes all the electricity to operate the ignition and has both low speed windings and high speed windings. The low speed windings make enough voltage to fire the motor and run under load up to mid 2000's RPM, which is where the high speed windings start making enough voltage to operate the ignition to high speeds.

A failing high speed circuit will still allow NO LOAD high RPM in Neutral, but that isn't good enough proof to condem a NON-returnable electrical part.

Always test correctly and PROVE any fault to be sure that you do not buy expensive UN-necessary electrical parts.

A DVA meter or a DVA adaptor for any volt/ohm meter is perfect to test and prove any ignition fault.

Check out this link to CDIElectronics Ignition Troubleshooting Guide, it spells out in great detail how to test most all outboard ignitions and exactly how to do it.

CDI Electronics Practical Outboard Ignition Troubleshooting