Yamaha I/O problem

[amp1974]

I have a 91 dynasty boat with a Yamaha 205 hp 4 liter serial #t2p100331. I have taken it to my local boat mechanic, and he has no solutions as of yet. He doesn't have a lot of experiance with these I/O's. The motor stalls when making a turn to the left or right. I can back off and bring and the boat into neutral and take off with full power. I can get by with more left turns than right turns generally. The rpm on the motor do not jump up during the stall like I think it would if the transmission was to slip in neutral. The prop is not slipping according to the mechanic, and the carb has been cleaned. Anybody with any ideas thanks in advance.

 

[searay3]

Re: Yamaha I/O problem

Start by doing some basic stuff. Junk in the fuel tank comes to mind. Water Separater/Fuel filter, tune-up. I would also be looking at the wiring back in the engine bay. There are a number of wires back there that could be routed over some steering hdwe etc that may have rubbed thru the insulation shorting out the ign. I would be looking to verify spark during a turn when it stalls. You will have to narrow it down to electrical or fuel first.

 

[Bondo]

Re: Yamaha I/O problem

Ayuh,.......

Capt. Ken shoud be along shortly,...... He's the resident Yamaha Guru......

 

[Capt Ken]

Re: Yamaha I/O problem

Thanks for the head's up Bondo. Being slack on my crusing the forums this winter. Sounds like you have a fuel delivery problem as in possible fuel pump. What is happening is, you for some reason or another, not keeping the carb full of fuel. When you turn hard left or right, it slings fuel away from one of the metering rods and you lose power. If you had a way to put a pressure guage on the pressure side of the fuel pump, you would probably find low pressure. The simple way to test this theory is to disconnet the incoming fuel line at the fuel filter on the lower starboard side. Install a squeese bulb for an outboard and reinstall. Have someone sit next to the bulb and before you make a turn, have them start pumping. If it doesn't stall, then either locate an air leak in the suction line or replace the fuel pump.

Being a Yamaha makes no difference in this problem. Its a GM 4.3 engine with Delco EST igniton and works the same as any other engine. So don't let the mechanic play the "I've never worked on one of them things before" excuse. There is nothing Japanise about the engine part of this system.

 

[amp1974]

Re: Yamaha I/O problem

Thanks I'll let you know what I find out.