Doral265BR496Merc
Recruit
- Joined
- Apr 18, 2022
- Messages
- 2
Good Evening iboaters.
Long time (many years) of reading, first time posting (my good luck with boats is hopefully only temporarily being challenged).
I have read many forums with similar issues and tried a few things that did not correct the issue.
Here is a quick over-view. I have a 2007 Mercruiser 496 (non H.O.) motor. I bought this boat used with only 93 hours 3 years ago, was expecting some mild issues due to lack of use. Instead a blew the block 3 hours in a 96 hours without even running it hard. 12 grand later I have a new block with existing components put back on it.
My issue is this, boat turns over and starts, but dies right away. Then another turn of the key or two with the motor cranking for about 2-3 seconds it catches and starts, it chugs along at a low rpm for a couple seconds and dies. If I start it a third time it will chug along at a low rpm but manage to stay alive and slowly the rpms come up to a normal warming the engine speed. Once it gain RPM but the engine is still not warm if I were to rev the engine it would cause it to bog down and die, I can advance the throttle and if i pull back quick enough it will stay alive. While advancing the throttle and its bogging down the engine you can hear a steady air sucking sound. This (along with some forum posts) led me to believe it was the IAC valve so I changed it, there was no difference. In the throttle body there are IAC filters I believe they are called, I replaced those, no difference. I brought it into my nearest marine mechanic (unfortunately not mercruiser mechanic) he ran his diagnostic tool on it and this is what they found.
"Upon initial Fire up crank position sensor and cam position sensor codes showed up. However after a few minutes of idling and engine was warm codes went away"
The boat runs perfectly once warm, sadly I ran it this way with the hard starts for two seasons, but tried not to use the boat too much due to this, as i don't believe its good for the motor to barely stay alive and chug along each warm up. This year I have to get this fixed. Nearest mercruiser mechanic is over an hour away by trailering it, if I cant figure it out I guess I will have to drag it in there and likely leave it there a month as they are swamped with boats.
I have always run 91 octane fuel in this motor since I have owned it, its up at about 120 hours now, a little under 30 on the new block.
I have videos of the motor struggling to warm up, but they are to large to post.
Thank you for any help/ideas you may be able to give me, much appreciated.
Long time (many years) of reading, first time posting (my good luck with boats is hopefully only temporarily being challenged).
I have read many forums with similar issues and tried a few things that did not correct the issue.
Here is a quick over-view. I have a 2007 Mercruiser 496 (non H.O.) motor. I bought this boat used with only 93 hours 3 years ago, was expecting some mild issues due to lack of use. Instead a blew the block 3 hours in a 96 hours without even running it hard. 12 grand later I have a new block with existing components put back on it.
My issue is this, boat turns over and starts, but dies right away. Then another turn of the key or two with the motor cranking for about 2-3 seconds it catches and starts, it chugs along at a low rpm for a couple seconds and dies. If I start it a third time it will chug along at a low rpm but manage to stay alive and slowly the rpms come up to a normal warming the engine speed. Once it gain RPM but the engine is still not warm if I were to rev the engine it would cause it to bog down and die, I can advance the throttle and if i pull back quick enough it will stay alive. While advancing the throttle and its bogging down the engine you can hear a steady air sucking sound. This (along with some forum posts) led me to believe it was the IAC valve so I changed it, there was no difference. In the throttle body there are IAC filters I believe they are called, I replaced those, no difference. I brought it into my nearest marine mechanic (unfortunately not mercruiser mechanic) he ran his diagnostic tool on it and this is what they found.
"Upon initial Fire up crank position sensor and cam position sensor codes showed up. However after a few minutes of idling and engine was warm codes went away"
The boat runs perfectly once warm, sadly I ran it this way with the hard starts for two seasons, but tried not to use the boat too much due to this, as i don't believe its good for the motor to barely stay alive and chug along each warm up. This year I have to get this fixed. Nearest mercruiser mechanic is over an hour away by trailering it, if I cant figure it out I guess I will have to drag it in there and likely leave it there a month as they are swamped with boats.
I have always run 91 octane fuel in this motor since I have owned it, its up at about 120 hours now, a little under 30 on the new block.
I have videos of the motor struggling to warm up, but they are to large to post.
Thank you for any help/ideas you may be able to give me, much appreciated.
