Engine or lower unit ?

Catback

Cadet
Joined
Sep 30, 2013
Messages
7
Was wondering if any of you have had this problem . Motor runs , idles fine , in reverse it runs great bout rip the transom off lol but in forward it wont run but 10 mph .....acts like its bogged down . I can ride it around for a little while sometimes its 5 minutes and sometimes its 30 minutes and it will all of a sudden take off like normal. But this only happens in forward , reverse does just fine .Iive never run into this kind of problem before , thanks guys for any imput you might have .

oh by the way its a 1990 150 black max

. It only does it in forward gear. When its in reverse gear it runs top notch full power and throttle . The engine should run the same wheather its in forward gear or reverse gear ..correct ?, witch tells me the its possibly in the lower unit some how. Unless there is something im totally missing lol I admit im not as familiar with working on higher power merc's
I tore down the lower unit and couldnt find any obvious issues other than may the pinion gear might be too low and need to be shimmed up a little but that wasnt even that bad .
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,473
Re: Engine or lower unit ?

Start and see if you have spark on all six cylinders. Sounds like it is running on 3 now.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,106
Re: Engine or lower unit ?

That motor should run with the same power in forward or reverse, however, I cannot imagine you can effectively test full power in reverse, so I think your premise is faulty.

I would test spark when it is running poorly (in forward) and report back.
 
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