L250TXRS fuel system help needed

[Yarb]

I am in the process of trying to get a pair of 1994 L250TXRS?s running. These engines have been sitting for over four years. They are no starts now. They were running when parked so removing and cleaning all twelve carburetors is going to be my first step.
My questions are:

1. Does the electric fuel pump run continuously when the key is on?
2. Is the electric pump a diaphragm or centrifugal pump?
3. What pressure does the fuel pressure regulator maintain on the system?
4. What actuates the fuel solenoids and when are they activated?

Any other advice you might have to offer will be highly appreciated.

Thanks, Yarb

 

[mygrady]

Re: L250TXRS fuel system help needed

After 4 years make sure that you have fresh fuel including good fuel lines. If fuel pumps have not been replaced- replace them. about 33 bucks each.
Remove plugs and spray some oil/wd=40 into each cyl.
You can clean all carbs and screw them up by having bad fuel going in at start up. Pump fresh fuel through lines with inlet hose removed from fuel filter under cowling.
replace all filters b4 starting.
I have a 94 225 and these carbs are very sensitive.
replace plugs.
Don't worry about everything else until you have done the basics.

 

[Yarb]

Re: L250TXRS fuel system help needed

Already replaced six fuel pumps, using an external pump, recirculated fresh gas through entire system by removing inlet to each carb and attaching a return line to recirc tank, fuel lines look good, sprayed oil into each cylinder, rotated by hand they turn nice and smooth, new plugs and filters ready to install.
Now back to my questions:

1. Does the electric fuel pump run continuously when the key is on?
2. Is the electric pump a diaphragm or centrifugal pump?
3. What pressure does the fuel pressure regulator maintain on the system?
4. What actuates the fuel solenoids and when are they activated?

 

[boscoe99]

Re: L250TXRS fuel system help needed

Let's start with some easy stuff first.

The diagram below shows the solenoids for each carburetor.

The engine CDI tells the solenoids when to open and for how long.

It is presumed that the pump must run continuously so any time that a solenoid needs to be activated that fuel pressure will be available at the solenoid.

It appears that the pressure regulator outputs a pressure of 1.4 psi.

Here is some descriptive text from a Yamaha book about the system on your motors.:

Electronic Carburetion System (ECS)

The ECS assists in delivering some of the required fuel to the intake tract of each of the six carburetors without using the normal carburetor circuits. Fuel for the ECS is drawn from the #6 carburetor float bowl. Any problem in the fuel supply to the #6 carburetor can affect the ECS operation.

Inside the YMIS (Yamaha Microcomputer Ignition System), a computer program signals when the ECS solenoid valve on each carburetor should open to add fuel. The ECS is designed to supplement the carburetor fuel delivery under the following conditions:
1. Cold starting
2. Warm-up
3. Rapid acceleration
4. Detonation
5. Rapid deceleration

Mr. Bolt is needed for a further explanation or to correct any bad data I might have provided. Contact him at www. boats. net at the Yamaha forums. See you over there.