1993 merc 3.0

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thunderguzzler

Cadet
Joined
Jul 17, 2011
Messages
8
Hey guys, been awhile. Had to re register due to moving and email change. Had a quick question, I have a 93 VIP with a 3.0l I/O, 19 pitch prop, merc alpha II drive, and at wot-40mph the engine is only turning at 2200rpm. My sticker on the air cover says she should be turning at 4800-5200 r's. What should I be looking into? She runs great and just had a recent tune up. My only complaint other than the above is that every once and awhile when I shut her down she will diesel. Any help would be great. Thanks, Chad
 
UNSUREBOATGUY

UNSUREBOATGUY

Petty Officer 2nd Class
Joined
Sep 14, 2009
Messages
117
Re: 1993 merc 3.0

I would check the accuracy of your tach. Speed at WOT sounds pretty much right on with the 19* prop.
 
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AviatorJim

Petty Officer 2nd Class
Joined
Oct 20, 2010
Messages
111
Re: 1993 merc 3.0

I agree with unsureboat guy. You can put an auto tuneup tach on for a quick check of the tack. You can also use a GPS to check the speedo. But sounds like you are running just right.
 
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thunderguzzler

Cadet
Joined
Jul 17, 2011
Messages
8
Re: 1993 merc 3.0

Btw my temp is a consistant 125. Seems low...No Stat in her?? According to the gps on my phone the speedo is right on at wot. I will throw a tach off and old truck I have on her next weekend and see what we got. But the tach seems to work al right from idle up thru the rpms.
 
Rocky_Road

Rocky_Road

Lieutenant Commander
Joined
Oct 8, 2008
Messages
1,798
Re: 1993 merc 3.0

thunderguzzler said:
Btw my temp is a consistant 125. Seems low...No Stat in her?? According to the gps on my phone the speedo is right on at wot. I will throw a tach off and old truck I have on her next weekend and see what we got. But the tach seems to work al right from idle up thru the rpms.
Click to expand...

I'm not sure that a car tach will work.

Look at the back of your current tach...there may be a 4, 6 and 8 cylinder rotating selector. You might find yours on the wrong one, and while there rotate it gently several times to make better contact.

Happy boating!
 
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