1989 Mariner 50hp 2 stroke surging/no top end?

aristotle · #1 November 29th, 2004, 05:55 PM

Hello All,

I've been a lurker for a little while, so hello. I like what I see here, ya'll will probably be seeing alot more of me now that Im out of my shell. First time boat owner. Bought a boat from a member of this forum. I'm not sure what he goes by, but it's a 1975 Bayliner Mutiny. See here: www.geocities.com/gamefishinchiquita It's still needs alot of work on the website, but as my boat, it's a constant work in progress.

Anyhow, I have been experiencing some surging with this motor. This is my first boat, a used boat, and in the 8 months I've owned my boat I have never had this problem. 2 weeks ago, after leaving my boat over night at the marina I noticed upon start up my motor, which is a little cold blooded, had trouble maintaining idle. So I swapped out the tanks, and problem solved. later that day I hooked that tank back up, sure enough, same problem except it will maintain idle, but at full throttle, I was only going 11-12 mph. I switched tanks again, problem solved. So I figure it was water in the tank that I left open over night at the marina. I bought a water seperator and hooked it up. Everything seemed to work. But now all the tanks I hooked up to it had this intermitten problem of it surging at full throttle, it idled just fine, but surged at the top end. Some times it would cut out, and sometimes it was fine. Any suggestions????

aristotle · #2 November 29th, 2004, 09:10 PM

Hey! How's it going D! Good to see you on here too. Nope, haven't rebuilt the carbs yet. Is it very hard? Know of anywhere online that has a detailed primer? You know I'm not shy to take on just about any project. I'm pretty handy with my hands. Jason seemed to think it was a sticking throttle? ????? Thanks again. I guess now would be the best time to do some rebuilding on my motor, I'm excited to learn.

dmonwai · #3 November 29th, 2004, 10:03 PM

Have the carbs been rebuilt lately?

I had a similar problem on my 50hp Yamaha. Mine would sometimes die at idle and be very hard to start back up and sometimes would only get to 3500 rpm at WOT. Sometimes I would be cruising around 5200-5300 rpm and the power would slowly drop off. It was very intermittent, some days it would run fine all day long.

I found the carb floats were sticking. I rebuilt the carbs and it runs great now.

PS: Its good to see you here, you will find lots of great info here. I've been here for a while but don't post nearly as much as I do at GF, I'm trying to change that now.

Damon

NathanY · #4 November 30th, 2004, 05:34 AM

Wow you did an awesome job on that boat. Now all you need is a 115 on the back of her.

KCLOST · #5 November 30th, 2004, 05:43 AM

Are the tanks vented? Do you have the vent open on both?

aristotle · #6 November 30th, 2004, 07:21 AM

yes, I made sure to check that the vents were opened. I even swapped out to my spare fuel line, and even tried bypassing my new water seperator filter, same difference. ???? Someone else suggested I check all the fuel lines inside my motor to make sure there are no holes. Another buddy suggested that I flush out the filter somewhere on the motor. ???

Thanks Nate! It's been fun, I'll make sure to update the site, I've got some more stuff I've done lately.