Mercury 25hp won't start in water

[UNCC Grad]

I have an 85 Mercury 25 hp SS that will run out of water with muffs but will not start in the water.<br /><br />Tonight I tried to test run the motor since getting a grounding issue resolved and it would not start in the water at all. It turned over a couple of times however.<br /><br />I was to the brink of insanity and exhaustion when I called it quits and took the boat out of the water. I had it strapped and ready to go home and just out of curiosity I tried get it to turn over. I choked it and squeezed the primer bulb and it turned over so I then turned off the choke and pulled and it fired right up. I only ran it a couple of seconds and then tried to let it idle to shut off as the idle screw has not been set correctly yet and this normally causes it to shut off. IT WOULD NOT SHUT OFF, it idled perfectly. <br /><br />Can anyone tell me what is going on? I really need to get this figured out by Friday night if possible.

 

[mellowyellow]

Re: Mercury 25hp won't start in water

go to the FAQ section here and read the post<br />"outboard won't start". excellent advice.<br />good luck,<br />M.Y.

 

[UNCC Grad]

Re: Mercury 25hp won't start in water

Thanks MW I checked that. The only thing on that list that might apply to my situation is a float needle failure causing flooding.<br /><br />I still cannot figure out why it will run with water muffs on, but not in the water. It is driving me insane.

 

[mellowyellow]

Re: Mercury 25hp won't start in water

when submerged, the water creates backpressure on<br />the exhaust that is not present on the muffs.<br />only real way to get the timing, link/sinc and<br />idle adjustments correct is in the water.<br />(also referred to as "under load")<br />I have heard that exhaust mufflers can create<br />needed backpressure, but have no personal exp.<br />with them.