2009 40TLR problems

[ragbul10]

I hope some of you can help me as you have in the past. I have a 2009 40TLR fourstroke. About a month ago I was coming off of WOT and it bogged down and ran rough while going slow (in no wake zone). I have since checked all fuel lines and replaced the fuel filter, the plugs do not appear fouled and the fuel pump is working. I pulled the carbs off and cleaned them with carb cleaner and compressed air and put them back on and still runs rough and vibrates even at idle. When I took it for a spin it would run fine for a minute and then like it was dying and keep happening at slow speed. The same would happen at WOT it would kick in run fine and then bog back down. The only other thing I noticed is if I start pulling plug wires while its running at idle it will die when you pull the top and second one at a time, but when you pull the bottom one it still runs. Anything I am missing or is it time for a shop trip because I am stumped.

[99yam40]

from what I have read the 4 stroke 40 has very small passages and are very hard to get clean and keep clean, plus you need special equipment to sync the carbs after reinstalling them.

I would have a good Yamaha shop tech with proper tools and equipment check it out

[boscoe99]

You have an F40TLR, not a 40TLR. It helps to state the precise model of your motor.

The carburetors on that model are particularly problematic. I am quite surprised that the motor has operated as well for as long as it apparently has.

First, the carburetors need to be fully disassembled and cleaned in an ultrasonic cleaner. Then rod out any passages that you can with a piece of soft copper wire. All other passageways need to have air blown through them for verification of operation. Without the use of an ultrasonic cleaner you may be, probably will be, wasting your time.

Yamaha has generated a procedure for a simple modification to the carburetor that will improve the chances of it being cleaned well. A permanent plug is removed prior to cleaning and then a screw and washer are used to seal the hole up after cleaning.

Take a look at the idle jet in your particular model. Compare it with the same jet used in early F40's. Yam went down a couple of jet sizes and it can be trouble. Either get the older jet and install it or maybe even go up a couple of additional jet sizes. What worked extremely well for me was to take both the idle and main jets from an F25 and install them in the F40 carburetors. A motor that could not be made to run well no matter what was done to it is suddenly and miraculously alive and well again.

I find it very important in that particular model to do a good sync and link using a vacuumate device.

[ragbul10]

thanks for your input and advice and ya I was looking into doing the ultrasonic carb cleaning on them this time after doing other research. You have any recommendations for an ultrasonic cleaner for a DIYer that's not overly expensive. And with the switch out of the idle and main jets use the same year (2009) F25 or does it matter.
Again Thanks