Mercruiser 175/v6 New Starter - Boat starts with muffs but hard to start in water

[kevinstan]

New to me 1987 SeaRay with 175/v6 Mercruiser I/O engine. Previous owner told me it would eventually need a new starter put on (Marine mechanic told him that) and instead of replacing he sold the boat to me. I purchased a new starter online and put the starter on. Tested on water muffs multiple times and boat started like a champ. Took it to the lake yesterday and it started as soon as I put it in and I ran it for about 30 minutes then stopped briefly. When I tried to start the engine back up it took about 15 seconds of trying before it would fire up. Stopped two more times during the day and both times it took between 15 and 30 seconds and longer of turning the engine before it would fire and start up. Once I got the boat home, I hooked up the water muffs again and it started right back up with no problem. Any ideas? I am lost on this one. Any help would be awesome. Thank you in advance!

Forgot to add:

Yes, I used the neutral throttle only switch and pumped a little and tried to get it going. That actually didn't seem to help at all. I tried multiple times like that as well even leaving the throttle in the 1/3 then the 3/4 position and trying again with no luck while on the water. At home it starts up without adding additional throttle at all.

 

[alldodge]

My first thought is the carb float level, might be flooding. Boat sitting in the water in most cases is a different angle then on the trailer.

On the water it will get full warmed up, have you tried getting it full warm and then let sit for same amount of time before starting again?

 

[kevinstan]

AllDodge: I haven't tried warming it up long then trying. I really don't like running on water muffs long at all and try to limit it to 3 minutes or less. On the lake I was at WOT for 10 to 15 or 20 minutes at a time then slowing down - then back up. Plenty enough to warm the motor. Not sure how I could replicate that well on the trailer.

 

[alldodge]

Agree your not going to be able to get it as warm as in the water, but 3 minutes won't give us time. I'm thinking the carb is flooding the motor. This is either by an incorrect float level, wore needle valve and seat, or other carb problem. If the boat has been trailered home it has had time for the air to circulate around the motor and clear out some of the excess fuel (if that was happening)

When its on the water loosen the flame arrestor and give it a run. The stop and remove the arrestor and look down the carb. See if there is any dripping or strong smell of gas. Normally if its flooding, the throttle is held near WOT and cranked to help give more air and clear out some of the gas.

 

[kevinstan]

I will check it out. I have ben doing some reading and have a few things I am thinking it could be:

1. Carb or choke not set correctly or carb flooding
2. Exhaust flappers not in place, and back pressure from the water making it hard to start

These are my first two I am going to look at. Hopefully it is something simple. It starts too good on the trailer with the new starter to have problems on the water.

 

[kevinstan]

If anyone wants to add to my troubleshooting list please post. I really hope it is a simple fix. The more info I can compile before diving in the better. Thanks again to everyone in advance!