2005 Mercury 9.9el - too slow ??

[Mikey_B]

Hi All,

This is my first post, I've checked archived messages and can't find an answer.

I have just got an 11ft Dell Quay Dory, which has a 2005 Mercury 9.9el outboard. The engine has only done about 8 hours use since new, and has been sat on a river for a couple of years without use. I took this boat out for the first time 2 weeks ago, it started like a dream, was really smooth and quiet. During it's first run I immediately noticed that it didn't seem to rev and I soon noticed that the water expelled from the pee-hole slowed down to almost a dribble. So I bought the boat back in and changed the impeller. I took this boat out again this week, and the pee-hole now has a fantasic rate of water flow. But the boat is incredibly slow... its more like a 4hp is fitted and not a 9.9. I've checked the cables, and the throttle opens fully and hits the stop when its flat out. It just really lacks power... almost as if it is refusing to rev. Has anyone got any ideas, pointers, or things I could look at.

Cheers.

Mike.

 

[Maxz695]

Re: 2005 Mercury 9.9el - too slow ??

did you change out the spak plug or plugs? Bad plugs will fire up to a certain PSI when there bad and then cut out

 

[JB]

Re: 2005 Mercury 9.9el - too slow ??

Hi, Mikey.

Welcome to iboats.

That engine should plane your dory. It is down on power.

Start with a compression check. If that clears, check for failing spark on one or both plugs, confirm spark timing, clean carb with special attention to the orifices in the throat.

Let us know what you find, and good luck.

 

[ReconDad]

Re: 2005 Mercury 9.9el - too slow ??

It's probably normal if it's a four stroke. I have a 2004, 9.9 Mercury Big Foot on a 14' Jon boat with the same problem.

One thing to check is the throttle cable adjustment. I found mine was only opening up to the 3/4 position at the carb when the tiller handle was turned to the full throttle position. Adjusted it and it made some improvement.

I can do up to 7-8 mph on a good day. I use it for fishing and it will troll all day at 1.7-2.0 mph . It also uses very little gas which is nice since it's up to almost $4 a gallon here.

 

[ReconDad]

Re: 2005 Mercury 9.9el - too slow ??

One thing to check is the throttle cable adjustment. I found mine was only opening up to the 3/4 position at the carb when the tiller handle was turned to the full throttle position. Adjusted it and it made some improvement.

Forgot you checked the cables.

I'm HP restricted on a lot of fishing lakes (10HP max} so unless someone has some performance suggestions or could recommend a shop the does performance mods, I will have to swap for a two-stroke.

 

[Mikey_B]

Re: 2005 Mercury 9.9el - too slow ??

Thanks for the replies, this is the first 4-stroke outboard I've had.. I've ordered a couple of new spark plugs and some carb cleaner, I'll try those and post the results.... I'm restricted to tide times as I'm coastal but will test it out ASAP. Is there really a big difference between 2 and 4 stroke engines ? Surely if the power output is 9.9hp Both types should be just as fast ?

 

[Mikey_B]

Re: 2005 Mercury 9.9el - too slow ??

Hi all,

It's been a while since I posted this, but here's an update:

I bought 2 new spark plugs - tested the engine and it made no difference.

However, while the boat was in the water I tried a few things out... when I start the engine in neutral, and pull the fast idle level all the way up the engine rev's really fast (as it should do)...

When I drop this back, put the engine in forward a push the throttle lever all the way the engine still only rev's about half of what it does in neutral with the fast idle level up.

I thought this might be a carb issue, so I stripped the carb.... it's like brand new inside, in fact all of the engine is immaculate... I reassembled the carb and it's made no difference at all to the speed of the engine..

I Spoke to the previous owner who has confirmed that when he had it, it easily had the boat on the plane, and infact he couldn't use it flat out without someone else sitting in the front of the boat.

The cables are definately adjusted correctly... I'm pretty much at a loss as to what could be causing this to not run run flat out... Anymore ideas before I make the expensice call to an engineer ??

Cheers.

Mike.