I have a fuel leak I'm trying to solve. In checking the forums the 2 most likely causes should have been the needle valves/floats in the carburetors, and or the fuel pump diaphrams.
It was 1st noticed last season when trimming the engine up at the end of the day dripping from drain holes in the lower unit area. At all times the engine ran perfect.
This year I'm trailering and have a better opportunity to flush out and examine the unit running with the fresh water adapter. I had some time and chose to rebuild the 3 carburetors. New needle valves, gaskets and removal and cleaning of the high and low speed yets and air yets. re assembled and ran again. The engine started even better and runs smooth - but still the leak.
Upon close inspection I see the fuel begins dripping from under the drive shaft after it runs for about 3 minutes or so at idle. From there it drips into the housing and thats where it finds it way to the lower unit and explains why it comes out when trimmed up.
The motor has 550hrs on it, si I chose to install 2 new fuel pumps 40 bucks ea to eliminate a chance of leaking diaphrams. Started up optomistically and sure enough - same problem.
2nd guessed my carb rebuild and took them off again to inspect the floats and needle valve set up. all needle valves free but 1 float a little crooked. Replaced that float, asembled and tried again. Same problem- 3 minutes or so and dripping fuel from under the drive shaft.
I had checked the float height to the manual, and was pretty close, but maybe a little low on all. I may take them off 1 more time and try to adjust the floats higher to spec in case the fuel pressure is unseating the needle valves. This will be the last try before bringing it to the shop.
Anyone have any suggestions for what else the cause may be?
Yes I used the yamaha rebuild kits. Reused the floats, but felt the settings were close enough. They were all below 5/8". Hoefully that turns out to be the problem.
I'll be breaking them down again and setting to .630" approx 5/8: which is the spec in my manual + - .020". I'm thinking the float level dropped over time and may be not keeping enough pressure on the needle valves at idle once the fuel pumps build pressure.