Hi, I have a 2006 Mercury EFI 150 2 stroke engine that is getting excess fuel in number 2 cylinder. I have changed over coils, leads and plugs but the problem stays with that cylinder.
The spark plug will stop firing after about 10 minutes of running due to the excess fuel. There are no error codes on the DDT. The plug comes out cleaned with fuel (definately not water)

Could this be caused by a leaking fuel injector? I have also been advised to check the low pressure fuel pump but I would have thought all cylinders would have been affected if this failed. All other cylinders are perfect.
Compression is all even as well.

Thanks in advance
Jake

check fuel pumps

other than that a sticking injector would do it

Its could be a injector or ECU, send them all to Tony Brucato @ Brucatosvs.com and have clean and balanced flowed, you can have all 6 cleaned and repaire for cost of 1 replacement and he can test ECU

Thank you for the above advice. I had one last go at fixing it before pulling injectors out, I did this by putting the boat in the water, warming the motor up and spraying 3/4 of a can of powertune down the intake until it stalled. Let it sit for 15 minutes then put the rest of the can in (while idleing) then took the boat for a run at various RPM. It seemed to run perfect for the 2hrs I drove it around.
Hopefully it cleared whetever the problem was. Could have been carbon build up on the tip of the injector or lodged in the reeds

Anyway all is good at the moment,

cheers
Jake.

The injectors are in front reeds so carbon build up highly unlikely, I would guess that you had a bad connection around the ECU harness and it was jarred during decarbon process. If it happens again check all the connection at ECU..

You are correct Faztbullet. I hit a wave going out and the prop caught a bit of air and when it all settled I had lost cylinder 2. I assume the jarring unsettled the faulty connection. I have since disconnected and replugged all harnesses going into the ECU and have had a perfect running EFI.

Thanks for your valuable input.

The only thing concerning me is it didnt record any faults in the smartcraft log.

The reason you did not get a error is everything was within the parameters of the ECU, it sent the signal to injector/coil but does not moniter the injector/coil itself.

Thanks Faztbullet, that puts my mind at rest.

Could you also tell me what temperature a 2006 Mercury EFI 150hp should be on when planing at 3500rpm. At present it warms up to 62 degrees Celcius while idling and then drops to 37 degrees Celcius once on the plane. these temps are taken from SmartCraft.
Are the temps controlled by the thermostats once the boat is above 1500 rpm or does the poppet take over?

cheers.

The cylinder head/block temps are maintained by the t-stats. When internal water pressure gets to around 10psi(increased rpm) the poppet valve is forced open, when poppet is open t-stats are bypassed in cooling system. I would rather have a water pressure guage than a temp sender as you can monitor the wear on pump impeller as pressure will drop as impeller wears.

Is it possible for the port cylinders to be runnning richer than the starboard cylinders? The motor seems to be running ok now but when I check the spark plugs the 3 port cylinder plugs look slightly wetter than the starboard ones, and so do the tops of the pistons when I shine a torch in there.
My fuel economy is still not back to where it was by about .3 of a kilometre per litre. It was 2 kilometres per litre it is now 1.7 to 1.8.

I was thinking of swapping over the digital temp sensors....but if the port side was reading colder would it run richer to just the port side?

I think I almost have this motor sorted thanks to you guys.

cheers.