Yamaha Problems - Updated

[RMC]

Just signed up for the forum but have been lurking for years. Finally decided to tap the knowledge of the board directly. I got boat problems.

I have a 2004 70 hp Yamaha 2-stroke. The first trip of the year was this past Saturday after sitting up since November. Prior to the first trip I changed out the fuel/water separator, new thermostat, new plugs, change the gear oil.

Got to the ramp and launched at Oyster Bay, first time leaving from Oyster Bay so cautiously idled out to Shell Point Beach, brought it up on plane out to the tripod. Seas where a little rough to go too far with the wife on board, so we drifted around on the flat to the east.

After drifting back to the channel we cranked up and headed into the Shell Point canals just for a little cruising. Cruised around for an hour or so then headed back out to the channel and bring it back up on plane then the engine suddenly dies. Got it cranked but won’t go past about a quarter throttle before dieing again. After a couple of tries I decide I will just idle back to the ramp. Now it won’t stay cranked at all. If I pump the ball while cranking the engine, I can just barely keep it going, but not enough to sustain idle speed.

I paddle back to a friends place in Shell Point, where she sits right now.

Any ideas from the forum?

[wevans]

That could be so many things. My first thought is a clogged fuel tank vent "dirt dobbers love em".

AND WELCOME ABOARD

[RMC]

Thanks. I will check that out.

The boat is a 2004 Key Largo by the way.

[Jumptrout51]

The Key Largo is not the problem.
Trash in the fuel or stopped up fuel vent is the problem.

[Tom Keels]

If you have the ability, I would hook up an external tank to the engine and see if she cranks. That will let you know if you have motor fuel issues or boat fuel issues.

[RMC]

Went down last night to try out the gas vent problem. Can't seem to find a gas vent??? Anyone with a Key Largo know where they hide the gas vent??

I took the cap off the gas fill and got it cranked. It seemed to run fine. I was able to run steady at about 3000 rpm for a few minutes and idle without choking out. I think the vent is the issue, now if I can just find the dang vent. I searched all around the boat. Even the neighbor came by to see if I needed any help and he couldn't find it either. The only hole I could find on the hull was the bilge.

There is another Key Largo next to my parking spot in the storage lot. I went by the lot on the way back into town to see if I could find one on that one. Sure enough, there was one just under the fill but it looked like it may have been put in aftermarket. Can't run around with the cap off. Guess I need to have a vent installed or see if they make a cap with a vent that fits.

Thanks for the help from everyone.

[Dabbler]

Same symptons with 200 Yam so thought I would tag onto this thread. No vent problem, not a motor problem. Marina guy says to remove pick up barb and destroy anti-backflow ball. Since I just caulked in deck plate, decided to check with the forum before proceeding. Please help (again).