Topic: Need help with 2003 Merc 200 efi (the smaller block)

This topic has 9 replies, 4 voices, and was last updated 15 years, 5 months ago by VONJ123.

Viewing 10 posts - 1 through 10 (of 10 total)

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December 30, 2010 at 1:11 am #261673

fishntrox
Participant

My 2004 Classic normally runs around 72-73 mph, but recently it started topping out at around 65 mph. Hole shot, mid range speed, and rpms have not changed any. My load has not increased and my prop is still in real good condition. I normally run on top end at a little over 5800 rpms. Any suggestions on why I might be losing top end speed and what to do to correct the situation?

December 30, 2010 at 1:25 am #261674

gchagler
Participant

Has your top end rpm changed or is it still 5800?

December 30, 2010 at 1:31 am #261675

fishntrox
Participant

Top end rpm is still the same. Still at 5800

December 30, 2010 at 1:34 am #261676

gchagler
Participant

What prop?

December 30, 2010 at 1:38 am #261677

Bass Cat Boats
Keymaster

I believe it is a 25p tempest

December 30, 2010 at 2:19 am #261678

Bass Cat Boats
Keymaster

Have the engine scoped and a compression check done.

December 30, 2010 at 2:19 am #261679

gchagler
Participant

The 72, 73 mph sounds about right, the only thing I can figure is maybe the prop slipping on the hub which I didnt think a Merc hub would slip. If it was a engine performance issue I would think you would lose rpm. In this colder weather it should gain rpms. If you are using an analog tach then it could be wrong and it could be a fuel issue.

December 30, 2010 at 2:23 am #261680

Bass Cat Boats
Keymaster

Did compression check 3 weeks ago. all tested between 121-125

December 30, 2010 at 3:13 am #261681

Bass Cat Boats
Keymaster

Then fuel related, hoses, filter and fuel. Maybe fuel pump diaphragm.

December 30, 2010 at 3:48 am #261682

VONJ123
Participant

I had the same issue with a 05 efi 2.5 liter. It was the prop. I lost the cup and lost about 7 mph. I got in sand on the river and lost the cup on the prop.
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