only getting idle speed on 40hp merc tracker

dcunningham

Cadet
Joined
May 30, 2008
Messages
21
Motor starts great but won't get any faster than idle speed If anyone can give some ideas of where to start looking for the problem that would be great.
 

Andy in NY

Commander
Joined
Oct 25, 2007
Messages
2,109
Re: only getting idle speed on 40hp merc tracker

What year is the motor?

I don't intend to insult you with this, but I had a simmilar experience. I am a newbie to boating, get the boat on the water, wont go faster than 3-4 mph.

turns out I had the warm up/fast idle lever up, and the throttle handle will let you put it into gear, but thats it... so you cant give it more throttle.


just my 2 cents...
 

dcunningham

Cadet
Joined
May 30, 2008
Messages
21
Re: only getting idle speed on 40hp merc tracker

It's a 2000 and thanks for the response andy I don't think that lever is the problem even when I lift that it doesnt seem to do anything.

any other ideas anybody
 

CastleRock4me

Seaman Apprentice
Joined
May 28, 2008
Messages
34
Re: only getting idle speed on 40hp merc tracker

Could be bad gas, did you winterize the boat? Could be an ignition problem. What are the events that leas to the problem?
 

dcunningham

Cadet
Joined
May 30, 2008
Messages
21
Re: only getting idle speed on 40hp merc tracker

I just baught the boat took it out and it overheated. I had a new water pump installed took it out again and it would hardly move and stalled a couple time when I pushed the throttle. It's been one thing after another. It has the same gas as when I got it. Could bad gas really be the problem? and how do I drain the old gas?

thanks kkruse
 

tredragon

Petty Officer 2nd Class
Joined
Jul 2, 2008
Messages
122
Re: only getting idle speed on 40hp merc tracker

1. does it start easily, ie. one pump on the bulb (when cold) and choke... starts within a few seconds?

2. does it idle really well but die when in gear and you attempt to throttle up?

If it starts hard, idles well, but dies in gear when you add throttle... my guess is the carb's are running lean (not enough fuel to get going under load).

Let me know the answer to these questions. feel free to PM.
 

dcunningham

Cadet
Joined
May 30, 2008
Messages
21
Re: only getting idle speed on 40hp merc tracker

Thanks for the response tre

Yes it starts pretty well and idles pretty good maybe a bit high and a bit of shaking. In the yard on the muffs it runs great accelerates fine in both foward and reverse. In the water it won't accelerate and eventually stalls when the throttle is pushed.

I'm hoping it's the carbs, the bottom carb is leaking fuel when the throttle is pushed under load.

I'm gonna check compression tommorrow It did overheat pretty bad but I braught it in and had a new water pump installed and I think they checked for compession I hope.

I checked the spark plugs also the top 3 had some carbon deposits, nothing that seemed out of the ordinary but the bottom was bone dry maybe even a bit sticky. I thaught it was odd one was different than the others.

Any help would be greatly appreciated I will Post any results I get
 

tredragon

Petty Officer 2nd Class
Joined
Jul 2, 2008
Messages
122
Re: only getting idle speed on 40hp merc tracker

if you know where your idle mix screws are (above choke port's on mine... check mercruiserparts)... just for the heck of it, on the muffs (although pref. in the water)... turn each one about 1/2 turn CCW at idle. The idle should get rougher but (again, if you're lucky enough to do this in the water)... your acceleration should start working. You can up the idle if you think it needs it. I just let mine lope. It doesn't die so who cares right? At least I can get it on the trailer now!

Oh, you really need to be in the water to see if your mix adjustments worked. Mine always ran like a top in the bucket, or on the muffs. Under load is a diff. story though.
 
Top