F40tlr

[justcallmecam]

Hi guys.
I am working on an F40tlr.
When i first looked at this engine it had a broken nipple on the fuel pump which i replaced.
Ran fine for say 20mins under load then began to misfire on number 2. I changed the plugs (they looked ok) and ran ok for another short while before doing the same.
swapped number 2 coil pack with number 1 and still number 2 is misfiring.
remove carbs and clean number 2, was very clean no signs of water or any corrosion.
engine runs again with same prob after about 5 mins.
carbies off again all given the once over and again she runs fine for about 10 mins before spitting the dummy again.
pulled the plugs again just for a look and number one looks to be burning a little lean and number 2 very lean (all white).
I have cleaned out fuel system twice when i pulled the carbs.
seems to me like something blocking a jet after running that short while but i just had carbs off again and everything seems fine.
I am really stuck as to what to look at next any help much appreciated.
BTW Im a diesel mechanic with experience on petrol engines (cars bikes) but no out boards. I dont have a manual for this engine and there wont be one available in the near future as I am located in a remote area.
thanks.

[sammplai]

F40 2011 issue with fuel

Hi having almost same problem how new is your motor is it a 4 stroke
There is a water/fuel cooler on mine it may be vapor locking
Temp of fuel is turning into a vapor.
Also there is a jet problem with these motors smaller holes then normal..
I've got mine in the shop now, first place couldn't find any thing wrong lol
The funny thing if I dump my fuel reserve inside cover and pump fuel back into it. It will run fine, but if I idle down a bayou for 15-20 min then hammer it no fuel spitting and acting stupid..

[justcallmecam]

Cheers for the reply Sammplai,
negative on the fuel cooler though, its straight from fuel fitting - secondary filter - carbies.
Im sure all fuel passages/jets are clear I found the carbs fairly simple to work on bowl off and top plate removed.
.................................................. ....................... ........... .... .. .

[HydroliftErik]

Cheers for the reply Sammplai,
negative on the fuel cooler though, its straight from fuel fitting - secondary filter - carbies.
Im sure all fuel passages/jets are clear I found the carbs fairly simple to work on bowl off and top plate removed.
.................................................. ....................... ........... .... .. .

if you have access to a ultrasonic cleaner, try one of those then.
i´ve done lots of these engines (named F40B in Sweden)
and it actually isn´t a very good engine, have replaced a number of carbs over the years.

try brotch(spelled right?) the jets, mainly the one on the top in the corner, Yamaha had a modify champaign on that couple of years ago.