1988-1992 Mariner 100HP engine, need advice

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Good afternoon everyone, I'm new to boat engines and this forum as well, however just bought myself 1988 bass boat with a Mariner 100HP outboard engine(not sure what year it is). The engine will start but it's running raugh, I captured a video, so please look and listen to it, and maybe you will have an advice for me. Also I would like to ask, where I can find a serial number on the engine ? Thanks in advance

Link for the running engine: http://www.youtube.com/watch?v=PeWQT-DFjWM&feature=plcp
 

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Re: 1988-1992 Mariner 100HP engine, need advice

up, need to get it done today, to test it out tomorrow on a lake
 

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Re: 1988-1992 Mariner 100HP engine, need advice

just share some of your ideas of what could cause the engine running like this. I've chekcked the fuel line and replaced fuel filter and fuel pump, still no changes
 

westexasrepublic

Chief Petty Officer
Joined
Jun 17, 2009
Messages
524
Re: 1988-1992 Mariner 100HP engine, need advice

spark seems erratic. follow CDI's instructions on how to test parts for the issue
 

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Re: 1988-1992 Mariner 100HP engine, need advice

what's CDI instructions ? can you forward me a link or something ? and obviously I don't have any user manuals for the motor
 

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Re: 1988-1992 Mariner 100HP engine, need advice

i just checked my spark plugs, one of them is dry, even after i cleaned the carbs, any ideas ?
 

NewBoater420

Cadet
Joined
Jun 8, 2012
Messages
6
Re: 1988-1992 Mariner 100HP engine, need advice

up, after starting the engine one of four spark plugs was completely dry, what this suppose to mean ? could this possibly be a blown cylinder ? i'm counting on you guyz
 

westexasrepublic

Chief Petty Officer
Joined
Jun 17, 2009
Messages
524
Re: 1988-1992 Mariner 100HP engine, need advice

Use a compression gauge to check all cylinders
 

mercury_blues

Recruit
Joined
May 20, 2012
Messages
3
Re: 1988-1992 Mariner 100HP engine, need advice

Sounds like its only running on some cylinders. The first thing i would do is connect a timing light with engine running, starting at top spark plug check each ignition wire for spark. If you have spark on all cyl get a good quality compression tester. Make sure you switch the stop switch that the tethercord attaches to on shift/throttle contol box to off so there is no spark as well connect jumper leads from each ignition wire to ground to avoid spark ans possible fuel igniting or blowing ignition components. Remove all spark plugs and chech compression on all cylinders it should be within 10% of eachcyl
 
Top