Motor Won't Go over 1100 rpm

[Dobb15]

My 1973 Mercuiser 165hp 6 cylinder wont rev over 1100 - 1200 rpm, gets on plain fine just doesnt get up to speed??? carb rebuild or Points??

 

[Don S]

Re: Motor Won't Go over 1100 rpm

wont rev over 1100 - 1200 rpm, gets on plain fine just doesnt get up to speed???

Check your tach, no way are you going to be on plane at 1100 ro 1200 rpm.

 

[tschmidty]

Re: Motor Won't Go over 1100 rpm

You can really get on a plane with 1200 rpm? But anyway not really enough information to go on. Is throttle moving? Is the carb opening all the way? Running on all cylinders (check spark)? Theoretically it could be your points or coil, have you checked dwell? Timing?

 

[Howard Sterndrive]

Re: Motor Won't Go over 1100 rpm

I've never been in a boat that will stay on plane, let alone get on plane at 1100 rpm. I suspect your tach is innaccurate.

 

[jtmarten]

Re: Motor Won't Go over 1100 rpm

Seriously??? Does the engine SOUND like its sitting just above idle? As others have said, there is no way you're going to get on or maintain plane at 1200rpm. Please use a simple, common-sense diagnosis - listen to the engine when you get on plane. If it SOUNDS like its running at a normal 4000-or-so rpm .... it probably is regardless of what the tach says. If the tach shows 1100-1200rpm ..... replace it.

 

[Dobb15]

Re: Motor Won't Go over 1100 rpm

Ok i will look into gettin a rpm gauge ... thank you for the responses, i thought it was weird too but this is my first I/O and wasn't sure. It is also running a 4 blade prop if that makes any difference.

 

[Don S]

Re: Motor Won't Go over 1100 rpm

Don't just throw a new tach on it, find out what the problem is. It could be a cracked coil tower, and the high voltage is arching to the - terminal of the coil, causing the tach to read wrong. It would also cause your engine to miss, which would also cause your lack of power> could all be due to 1 bad plug wire or spark plug.

 

[Dobb15]

Re: Motor Won't Go over 1100 rpm

ok thanks good to know, i will get on it and let you know

 

[Dobb15]

Re: Motor Won't Go over 1100 rpm

Hey i was just wondering is book #1 the proper manual for my 73 mercruiser 165 inline 6?? i have a manual for 63 - 85 mercruisers but would like something more specific!!

 

[Don S]

Re: Motor Won't Go over 1100 rpm

Hey i was just wondering is book #1 the proper manual for my 73 mercruiser 165 inline 6??

Yes, It will cover both the engine and the drive. It is an OEM sevice manual, sounds like that 63 to 85 is an aftermarket manual. probably Seloc or Clymers

 

[bruceb58]

Re: Motor Won't Go over 1100 rpm

And it could be the tach itself causing you problems. Remove the wire from the coil that goes to your tach and see if that helps.

 

[Dobb15]

Re: Motor Won't Go over 1100 rpm

I have discovered the issue !!! this is a new to me boat and the throttle linkage on the carb was loose not allowing full throttle, as well as why is felt like it was jumpy. My tach began working again fine for a few seconds then messed up again. at full throttle it says i am only running 2000 rpm, Could this be just a loose wire??