1998 Mariner 150 hard start

[Autowizzard]

My buddy bought this boat a year ago used and Iv'e been trying to help him with it, It's a 1998 Mariner 2.0 litre 150hp It's hard to get started especially when it's been sitting in the water for a while. It normally starts and will run on the trailer no problem but once in the water it's a different story, If it starts and you warm it up for a minute you can drive it all day no hesitation sputtering etc, It's a big deck boat and it pulls strong etc, Pull it into a dock let it sit for an hour and then it will start, stall spit and no start, It happens more to him as when we test drive it I guess we don't let it sit long enough, The time I caught it acting up I was able to verify spark on 3 of the cylinders then it started so I'm assuming a fuel issue? Any advice would be greatly appreciated.

 

[fastback4]

Re: 1998 Mariner 150 hard start

My 1999 Merc 60hp 3cyl. has this same problem and i'm convinced 1 of my 3 carbs needle and seat is not shutting the fuel supply off and allowing fuel to enter the cylinder as my boat sits in the water (river) after running mid-throttle for 20 min. or so.. It always starts well on the trailer even after a good warm up after sitting 10min. or so...I tested my belief by clamping off the fuel line after the primer bulb with a Snap-on hose clamp. We ran the boat in the river up to operational temperature, stopped and clamped the fuel line, and sat for 10 or so min. The engine started right up. Before this, it was flooded and i would have to feather the throttle to get it to run smoothly. Plus #3 plug was wet with fuel so there was lots of smoke. I will take #3 carb off this weekend and check the needle and seat. I'll report back with my findings...........Tom