Originally Posted by 85aetyamahauser
Looking for advice please. I have a Yamaha 85 aet pre mix power trim motor. I have found it has become very heavy on fuel. There is quite a bit of fuel mix ( the fuel that runs out is quite substantially oily) running out from the front of the carbs if I tilt the motor say when we get to a shallow area and switch off. The motor also runs on after switching off the ignition for around 5 to 10 seconds.
I am mixing oil fuel 50:1. shell nautilus
For example we ran around 5km or so on the weekend . Some at 4000 rpm and some around 2500rpm from spot to spot fishing. We used around 10 to 12 litres of fuel.
Any help please.
not sure what kind of boat you are running, but running at 2500 you probably get less than 2 MPG, and 4000 maybe around 4MPG but depends on the load you are pushing and how it is propped
Look at this site to see if you can find something close to what you have and see what kind of performance they got at different RPMs. 90HP will be close to your 85 is my guess
Performance Bulletins | Yamaha Outboards
When key is turned off the spark should not get to the plugs so should not keep running, that is one of your problems you need to look into
when running some fuel mix spits out of carbs and collects in the silencer on front of carbs, when the fuel evaporates it leaves a real oily residue that may be what you are seeing when you tilt motor