Mercruiser 3.0 engine problem

bjromaine

Cadet
Joined
Jun 24, 2013
Messages
20
I recently acquired a 1998 Glastron SE175 with a Mercruiser 3,0L, Alpha sterndrive.
While waiting for the delivery of a new starter (the old started stranded me on the lake) I did a general tune up, Plugs, distributor cap, rotor, fuel filters and checked all oils.
The engine is difficult to start and seems to be too rich as I have to advance the throttle in neutral quite a bit to get the motor to run (too rich on the carb?).

But after the engine is warmed up there is a band of RPMs, on the low side, about 1000 to 2000 that the engine stutters and sometimes stalls when accelerating a small amount. If the acceleration is advanced a large amount it will gain speed quickly about 60% of the time without the stuttering.
The boat was purchased from an older couple that used it very little and probably never were at WOT very much.
IF WOT is acquired it runs very smooth and fast. Just below 4800 RPMs, 37MPH with 4 people.

I did run the boat last week for about 30 miles and it seemed to run fine. Last week I added stabilizer but this week forgot to.
Could it be the lack of the stabilizer and/or carb adjustment?

Thanks for all assistance. This forum does indeed rock.
 

hall832

Petty Officer 1st Class
Joined
Sep 6, 2012
Messages
234
From your description I am hearing Carb Rebuild. Very easy carb to rebuild and the kit is readily available. Sounds like your idle circuit has restrictions. double triple check you have cleaned the carb 100% correct. it is the most frustrating thing to put it all back on the motor, test it and have to do it all again. I have learned to take my time and do it right the first time. good luck
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
^^^ Yep, definitely sounds like carb issues, time to rebuild it. The 1000-2000 RPM bog is the accelerator pump in the carb not working.

You'll want to get a bucket of carb dip, strip the carb down (no plastic remaining) and soak it overnight. The next day rinse everything off with water and use a compressor to blow out all the passages. You'll also need a carb kit and the OEM manual. Be aware that you'll need to make carb adjustments on land (idle speed and mixture) and then final adjustements once the boat is in the water, warmed up, idling in gear.

Have you looked at the drive lube, water pump impeller in the drive and bellows,,, or know when they were serviced last? These are very important to check on a used boat.

I don't have a link for the OEM manual, but someone should be a long that has a link. (Or just look at some old Mercruiser 3.0 threads)
 

tinkerguy70

Petty Officer 2nd Class
Joined
Oct 12, 2012
Messages
190
Sounds like carb issues to me as well, anyway, here is the link to the online manual:
 

bjromaine

Cadet
Joined
Jun 24, 2013
Messages
20
thanks for the information. BTW that link is specific to Evinrude. My motor is a Mercruiser. I will find the necessary info though. Does anyone think using some carb cleaner rather than rebuilding would help?
 

BruKen

Seaman Apprentice
Joined
Feb 26, 2014
Messages
48
rebuilding the carb from kit is so easy, quick and cheap that I'd do it anyway just to check it off the list and have peace of mind that it's one less item to be concerned about. I did mine recently, the float level was wildly out, and the difference afterwards was dramatic.
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
Carb cleaner isn't going to fix the dried out rubber parts, you need to rebuild and kit the carb.
 

bjromaine

Cadet
Joined
Jun 24, 2013
Messages
20
I finally got back into the boating frenzy when the weather improved. After replacing all the bellows (exhaust was shot), changing all oils etc I also used Gumout Carb Cleaner. If this did not work I would have ordered a Carb kit, but spraying the carb while running solved the hesitation when accelerating. It now runs great, smooth, fast and much much quiter.
Thank you all.
 

philipp10

Seaman
Joined
Aug 8, 2012
Messages
61
Smart guy, you did the simple things first (spray out the jets) rather than tear apart a perfectly good carb.....if it ain't broke....
 
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