Yamaha F50 '02 w/ "dead spot"

[<joedawg>]

I have a '02 Yamaha F50 that has two problems that might be related... First problem is that it has a "dead spot" on the throttle... About halfway forward, just before enough power to plain, the motor, when agressively moving the throttle forward, has a dead spot that stalls the engine... If proceeding at a gradaul pace thru this "dead spot" then just a slight hesitation... Also, the engine does not like to start... Need to keep pumping the primer bulb to keep a good flow of gas into the engine... Any suggestions out there?

[<boats.net>]

Sounds like a carb problem. You can rebuild carbs but it takes special tools (vacumn mate or gauges)to syncronize carbs

[<joedawg>]

Using the boat the past few times, I have been able to start it with now with no problem... After priming, I must lift the idle throttle to full, turnt he key and hodl in for 5 seconds, and she starts on sometimes the first, but almost always on the second turn of the key.... I am still having the dead spot issue when I move the regular throttle forward in a manner other than slow... I have always been hauling other trailers when heading up and back from the lake so its been hard to get the boat home... I might just have to "bit the bullet" and take a quick trip to get it in to a shop but am wondering if there is anything else to try...

[<Ed McKenna>]

Today I replace the primer bulb on mine because I was having similar symptom to yours. Needed to prime before starting, as well as sometimes after a stall.

Replacing primer didn't do jack shit other than make for a nice gas mess in the bilge.

Then I did the fuel pump diagnosis. THIS REQUIRES some one to prime the bulb while you inspect the pumps. My recommendation is that you do this first while all the pumps are installed looking for gasket leaks/drips down the hoses. Feel before and after priming with your finger also. Then if no leaks take each pump off individually by removing the bolts (not the screws). Leave hoses connected. Prime the bulb while looking at the back of the pump. Some gas will weep out of the holes where the bolts are. This is normal. However if the center hole bleeds any gas, then the pump is shit. Replace it for 40 bucks.

In todays inspection of mine I had a bad gasket on one of mine. Make sure when you replace that the gasket is on and in GOOD condition.

The only exception to my problem versus your was that mine just lost power like the line was cut while running at high RPM. The cause of this I'm sure was that the line was sucking air. I replace today and mine is now running fine and dandy w/ the exception that my port and starboard sides of engine are still running at different temps...

Good Luck, Ed