Merc OB Runs at 3200 rpm

[Kenny Skees]

Hello,
I'm new to the forum, and have a question on 75 HP merc 2 stroke, 2005. The motor will only go up to 3200 rpm. The last 2 times I ran the motor, it would achieve 5200 rpm. I took it out yesterday, and it took 20 minutes to start, then would only go to 3200 rpm. When I took it home and fresh water flushed the motor, it started on the first crank. Any input would be appreciated.
Thanks.

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

Hello,
I'm new to the forum, and have a question on 75 HP merc 2 stroke, 2005. The motor will only go up to 3200 rpm. The last 2 times I ran the motor, it would achieve 5200 rpm. I took it out yesterday, and it took 20 minutes to start, then would only go to 3200 rpm. When I took it home and fresh water flushed the motor, it started on the first crank. Any input would be appreciated.
Thanks.

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

Ok, I got no takers, so I'm going out again and see if the issue re-appears.
Bad gas?
Spark plug issue?

 

[Plainsman]

Re: Merc OB Runs at 3200 rpm

Welcome to iBoats Kenny!

Do you have spark at all cylinders? Have you done a compression test on all cylinders?

 

[AMD Rules]

Re: Merc OB Runs at 3200 rpm

Is that motor under warranty?

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

I have done no compression test or checked the spark plugs. I took it out a little while ago. I filled the tank with a little over a half (9 gallons) a tank of 87 octane, it started on the first crank and ran 5300 rpm without a hickup. I turned it off for a half hour, loaded the wife and kids in, then it wouldn't start for about five minutes. Then it ran fine for about a hour and a half, then wouldn't go over 2400 or so rpm, and started hesitating . I'm thinking a bad/old gas issue. I figured the old gas would have mixed with the new enough to make this issue go away, but I guess not.

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

The warranty ran out in July!!!!!
I bought the boat and motor and trailer last week. I had the package checked over by a mechanic. He said the motor was so new that it didn't need a compression check. OUCH!!

 

[Plainsman]

Re: Merc OB Runs at 3200 rpm

When your having problems, try pumping the bulb and see if that helps. If so, the fuel pump may need a rebuild.

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

I'll give it a try.
Thanks.

 

[andy6374]

Re: Merc OB Runs at 3200 rpm

Get your hands on a external portable tank and run some fresh fuel and see if this helps

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

Get your hands on a external portable tank and run some fresh fuel and see if this helps

Ok, good idea. Thanks.
Is there an additive for old gas, or can it be pumped out and used in a car or lawn mower?

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

Get your hands on a external portable tank and run some fresh fuel and see if this helps

Ok, good idea. Thanks.
Is there an additive for old gas, or can it be pumped out and used in a car or lawn mower?

 

[Kenny Skees]

Re: Merc OB Runs at 3200 rpm

Thanks for the tips.
I pumped out gas, put in a fuel additive, cleaned spark plugs, friend ( mechanic ) cleaned carburators, put in new gas and it ran fine. Not even a hiccup. I put the old gas in my jet ski and it ran fine too.
Thanks again.