Yamaha F40 Issue

[UnderwayMakingway]

Dear ALL.

I have issues with my yamaha F40 out board.

I will be able to run it with no problem for a good run. Than when I will shut it down and start it again about 15 minutes later, it will stall as soon as I give some revs. After one to two hours, it will run again. Then so on...
It as been going on like this for while. It is a puzzle to me and Yamaha techs. I have changed the water pump, fuel pump, Thermostat, serviced the oil, Cleaned the fuel tank, Racor filter, CDI, carburetor.

Is there any one who have the same issue ? Have any suggestions ?

Thank you.

[boscoe99]

What is the specific model identity?

[UnderwayMakingway]

F40FET would be the identity.

[almetelo]

You are sure is a F40FET or that it have carburetors?

F40FET is EFI

[boscoe99]

OK, now give us the complete engine identity. Will be on a data plate on the side of the motor.

[UnderwayMakingway]

From the Plate :

Yamaha 6BG, F40FET, L, 1022194, C

[boscoe99]

From the Plate :

Yamaha 6BG, F40FET, L, 1022194, C

This is a fuel injected model. It does not have carburetors. Does not have a CDI either.

Does this happen after you have been idling for a period of time, after running at power for a period of time, or???

Are the fuel cooler passages (both fuel and water) free and clear? Is the vapor shut off valve working correctly?

If you let the motor idle for a couple of minutes after being started does it still bog down or not when you advance the throttle?

[UnderwayMakingway]

Thank you for the reply.

This is definitely the model number taking from name plate on outboard. I have been told that it is Asian version that could had have modifications.
Because there is a CDI (I changed it) There is a carburetor (I checked it).

What is happening is I will be able to run around at good RPM, lets say 30 minutes. Then when I will shut the engine down and start it 15 min later it will stall as soon as I get in gear. On Idle you can feel it struggling. Then after an hour or two it will run again OK.

[UnderwayMakingway]

And yes sometimes it will stall at idle.

[arny]

You got a fuel injected 2012,no carb.What you see is a trottle body.
You got no CDI,but a ECU. I would suspect a bad fuel pump and/or fuel filter in the VST. I have also seen someone put the fuel filter wrong way with stange symphomes.

[UnderwayMakingway]

Thank you.

This is great info.

I did change the fuel pump. I will double check about the carb and CDI. Just got that CDI or ECU swap.

I am currently in Palau, I have been dealing with this issue since months. Had several Yamaha tech in Malaysia, Here in Palau... They did had that issue before my time also.
No one so far can put the finger on it.
Please keep these info coming. I look forward to solve this one.

Thank you.

[99yam40]

can you take a picture of the so called carb on the motor and post it on here?

Need to make sure the fuel cooler and water lines are clear and flowing water cooling off the fuel

[UnderwayMakingway]

I apologize, I did mistaken the Carb and wrongly named ECU.

However, I did clean the fuel line, open and clean the top part of the throttle body.

Something I notice though is near the piss hole, where the water come out, There is an other hole above the oil drain screw and have no water coming out.
Should be not water come out when High rev or at all time ??

[99yam40]

I am not sure about the others but I have no clue as what hole you are speaking of. A picture may help.

Can you locate the fuel cooler?
And disconnect the water lines to it to check for a blockage/restrictions

[UnderwayMakingway]

Here is the Picture.

The middle hole (above the drain screw) should be not have water flowing out at high rev or at all time ?

I seem to remember that I have seen water coming from that hole. It was at high rev.