[cmacdol]

Year 2000
Model SX 250 OX66 Saltwater seris
H.P. 250

Boat get up and runs, If we push it hard (4900rpm's)
it stops in it's tracks.
It will re-Fire and Cruise , if you take it easy.

it's not the Suction side sreen on the Pump housing, nor the Fuel filter on the Motor.


any Ideas?
Les

 

[Lone Ranger]

Fuel Pump/s!!Have a Buddy that had the same problem/same Motor,Run Her up,then it felt like someone would just turn the key off.Started right up,would idle fine,run Her up and the same thing.Think it was the High Pressure pump if I remember correctly. [Mike]

 

[katman2860]

Have you checked the filter inside of the vst,sounds like it has clogg in it

 

[cmacdol]

What does "VST" stand for?


Les

 

[master wrench]

Vapor Seperator Tank.

 

[cmacdol]

Well it's not the screen in the VST, not the High pressure fuel pump and not the 3 fuel pumps,
running out of options.

I'm going to try, pumping the bulb while running.

Les

 

[cmacdol]

Pumping the Bulb helped for about 10 seconds
Im pretty sure the problem is fuel.
Les

 

[Lone Ranger]

CK. the screen on the Fuel pick-up in the Tank and the CK. valve.And make sure the vent for the Tank is clear.

 

[cmacdol]

Not sure how see a screen in the tank?
It's just a welded tube sticking out.

What Check Valve?

If the vent is clogged wouldn't ,opening the Fill cap , check it?

Les

 

[katman2860]

You need to hook up a pressure guage between the low pressure& high pressure pumps to see if low is staying at 3-5 psi,then apressure guage hooked to the valve on top of the vst to make sure the high pressure is 45-50 psi otherwise you will be going in cicles to find the problem,if you continue to run the engine as it is you will burn it up!

 

[cmacdol]

Thanks, I'll buy another pressure gauge tommorrow , when the stores open.
Kinda hard to check at High Rpm's?

Les

 

[Cool Change]

When is the last time you replaced the impellar? It may be overheating and droping out the rpms . This is a safety measure most all engines now have. Plugs fouled?

 

[cmacdol]

Shouldn't the Alarm sound if it takes safety measures?

Les

 

[katman2860]

Yamaha's warning system will knock the rpm down to 2400 and not let you run over that rpm

 

[cmacdol]

O.K. running in a big trash can.
Fuel pressure 40psi at idle 50psi reving the throtle.
Vaccum 3in.

Maybe it's not a fuel problem after all?

Les

 

[katman2860]

Pressure needs to be checked with the boat in the water at the speed it is loosing rpms,low pressure on feed line to vst,high pressure on top of vst,running it without a load is not really checking the problem

 

[cmacdol]

The factory says the fuel pressure should be a constant 35psi.
Maybe the pressure regulator is bad?
I removed the Vaccuum? line from the pressure regulator and the boat ran the same.
Maybe it is the pressure regulator?

Les

 

[katman2860]

Les,What was the pressure reading betwwen the low pressure pumps to the vst reading while you were out running your boat in the water and was the vst maintaining 35psi while running at 48-4900 rpm

 

[cmacdol]

Never did check between the the Pumps nor while the Boat was running.

Les

 

[katman2860]

In order to eliminate the pumps as a possible problem it needs to be checked while yoyu are underway