115 cuts out at 5k rpm

[markw863]

Bought used from a dealer (on consignment) recently w/ about 650 hrs on it. Dealer said he did "yearly service." The dealership changed hands and now I cannot find out what was done.

I have a few questions. I think it is a 1998 (originally sold 4/99). Model S115TLRW. ID 6E5L-403128.

1) Runs fine up to 5,000 or 5,100 rpm. Above that, it sputters and chokes down and comes off plane. No buzzer. It keeps running and you can go right back to 5k after returning to neutral. Fuel filter at primer and on motor look clean (is it enough to look clean?). What to do?

2) I've only had one other 2 cycle, but it does not seem to use much oil. If I had to guess, it has used a gallon of oil to 75 or more gallons of gas. Maybe that's just the way it is. Owner's manual does not say what ratio is should use. Is there a way to tell if it is using enough oil?

3) It is a bit hard to start both cold and hot. Cold, I can understand, but it seems it should fire with one turn of the key hot (after fishing etc.). We choke it cold and give some throttle and it will fire after two or three attempts. It's basically the same process, including choke, when hot. Is this normal? If not, can I fix it?

Any help would be appreciated.

[jb123]

when it cuts out, have someone check the pump ball to see if it goes flat...also pump it when it cuts out to see if it helps.
use an auxillary tank run to the motor fuel filter to isolate boat tank from motor. could be vapor lock at the tank/vent side, weak/bad fuel pumps, or most commonly, dirty carbs.

[markw863]

I took it out and the primer ball did not collapse, but it did empty out (when you squeeze it, it collapses).

I took off the gas fill cap to see if the vent might not be letting in air, but had the same problem.

After it dies, you can eventually prime it to where the bulb is full. Then it will open up and run great--until it drains the bulb and dies.

There is a fuel/water seperator on it. I have no idea when the previous owner last changed it.

Is my problem most likely between the primer bulb and tank, or between the primer bulb and motor. It seems strange that the filters (after the bulb and on the motor) could cause this, or the fuel pump is causing it (why would it open up at all?).

Any help is appreciated.

[jb123]

check the exhaust, with a bad diaphram you will see unspent fuel.

[markw863]

This is going to sound like I'm an idiot, but what and where is the diaphram and what is the fix? I don't recall gas in the water, and I think I would notice that.

I can change the fuel pump, but if that's it, would it run WOT at all? It does until the gas starves out.

[Dennisg]

Hi, you might want to check the strainer on the end of the fuel pick-up tube in the tank. If you have one, I bet that it is all gumed up, and restricting the fuel flow. Thios is a problem that is often overlooked, and I have had it on my last three boats, which I have had from new. Before you take the carbs apart, or the fuel pump, check this problem spot. Sounds to me that you are running out of gas, then it runs ok till you hit that point where not enough gas is supplied, a fuel supply problem. The first thing to do is to change the fuel filter/water seperator, then take the fuel pickup out of the tank, and take the screen and through it away, you do not need it with the in line fuel filter/water seperator, this is what I have done, and after doing it, I did not have any more fuel related problems.
Please let me know if this helps, Dennis

[ January 30, 2007, 08:37 PM: Message edited by: Dennisg ]