Yamaha Fuel Pump Question

Pull the 2 bolts that hold the fuel pump to the block, only those 2 (leave all the other lines hooked up and screws alone)

With the 2 bolts out prime your primer bulb and see if gas squirts out of the back of the fuel pump. There is a little hole in the back of the pump gas should not come out of it.

If it does then R&R the fuel pump and go fishing, if it doesn't then you have a different problem.

Let me know
Standing by

 

Exactly what Creek runner said, but let me add a small amount more...
On the fuel pump, theres a small tip of the diaphram that sticks out on top. Is it white or black?
White is bad in this case.
Also, you said you replaced the primer bulb. Did you use an oem yamaha, mercury etc brand or attwood, moeller?
Aftermarket bulbs suck

 

Yours stick out the side because your pump is mounted sideways.

The white tabs could indicate a problem with the diaphragm, Yamaha switched from the plastic white diaphragms to black rubber style due to issues with the white ones; but I have never seen a fuel pump with the white tabs that didn't test bad (You tested yours with my previous post) and was intermitting. Which your issue seems to be.

1st) Pull a fuel sample disconnect the primer bulb from the engine side and pump some fuel into a clear glass jar. Check and make sure there is no water or thrash.

2nd)  When you replaced the primer bulb did you use a Yamaha one or after market. If after market switch to an OEM one, I like Mercury's best but any OEM will do.

3rd) The next step would be to run the boat on a portable tank with different fuel line and primer bulb.  This will tell you if you have a boat problem or motor issue.

4th) ) R&R the fuel pump,

Intermitting problems are always the hardest to diag!

 

Lol they are a bit "out of the loop"..
Yamaha upgraded to the black neoprene diagphram a couple years ago.
They might just be trying to get rid of old stock
Dont buy a white one

 

I went back and pulled the bulletin and it did not affect your engine.

Also like I said in my previous post, I have never had a fuel pump that was bad test good. You did the test I told you so it's probably not your fuel pump.

Pull a fuel sample, check you filters, you already replaced the primer bulb. Has the engine acted up again?

 

I experienced a similar problem on my '02 90 and did all the things you have done because I didn't want to clean carbs like G at CFM told me to do. I finally broke down and cleaned the carbs to find a bunch of crud in the float bowls. Haven't had a problem since.