My Mercury 90hp This has become a quest

psjr57

Cadet
Joined
Jun 19, 2009
Messages
15
Please feel free to join me in my adventure to get my motor running the way it should. I have been at this for 3 months now. I have tried several advice from people on boards such as this. The main problem is that my motor bogs down after several minutes on the water. It does fine on the muffs and I don?t have any problems starting it. I have a 2003 Mercury 90 HP 3 cyl with CDM ignition (OT605708). Here is what I have done so far.

Symptoms
The boat will start fine on the water it will go up to 4000 rpms for about 5-8 min and then it will bog down to a crawl. This Sunday I was on the water and I decided to stop the motor and pour some more fuel. Well after about 5 min of fueling I turned it back on and it took off like a champ. But you guessed it 2-3 mins, it started bogging down again. I decided to go back to the ramp and call it a day. While I was waiting for my Dad to back up the trailer, I decided to turn it off again and try, well once again it took off great and then 3 mins later it did it again. One thing I should mention, the horn alarm that is located behind the ignition switch started blaring. One continuous beep. It will not shut off. As soon as the key is turned it will start beeping.

Things done to motor
I have installed new plug, new wires, new, primer bulb, new in-line fuel filter. I have checked the vent in the fuel tank, emptied out old fuel and I have poured new fuel. I have checked the anti-siphon valve. I have checked the carbs and everything seems good. I have checked for spark and the #1 cylinder seems to have little to no spark. The other two have good spark. I swapped the #1 cylinder CDM and #3 cylinder CDM and there was no difference. I still had weak or no spark on the #1 cylinder. I was kind of hoping it was the CDM. But no that would have been to simple.
 

steam_mill

Chief Petty Officer
Joined
Jan 16, 2002
Messages
413
Re: My Mercury 90hp This has become a quest

I had a very similar problem with my 2003 90hp. I lacked spark to one of the plugs. Swapped CDM's, no spark on a different plug. Figured CDM. Run up to the dealer, get a new CDM, still no spark on one of the plugs. Gave up, pulled the boat out of the water and took it to the dealer.

Got it back from the dealer, he says he changed a CDM and it now runs perfectly. Well, the bill was only $80. When I bought the CDM, it was $75. I never figured out what was wrong.

I've actually tried to figure out how the ignition works. Never could do it...

Good luck.

Joe
 

psjr57

Cadet
Joined
Jun 19, 2009
Messages
15
Re: My Mercury 90hp This has become a quest

So your saying that you swapped out the cdm with another existing cdm and still did not get spark. So it actuality you installed two new CDM's.
 
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