2000 Merc 115ELPTO 2+2 problem

[Crankypistol]

I thought I had a fuel starvation issue but I believe it is in the 2+2 system. I need help.
Fires right up. Put in gear, hammer down and bogs badly. Will come on plane and run 4100 rpm. When you first hammer the throttle you can feel for a split second the power of all four cyl but then it’s gone.

Running on a hose. I can idle in gear or out up around 2500-3000 rpm. All four coils have spark but at this rpm I can unplug the bottom two coils and there is no difference in sound or rpm of the engine. Is this power pack related or what?

 

[racerone]

No, no-----At idle the motor only runs on the top 2 cylinders !----It will have spark on all 4 cylinders all the time.----The bottom 2 carburetors kick in at 1800 RPM or more.

 

[faztbullet]

Check the accelerator pump and clean the injectors under ignition mounting plate.

 

[bobbyc]

The absence of idle mixture screws on the bottom two carbs confirms the 2 plus 2 designation. If it is a 2+2 the bottom 2 cylinders will "kick in" around 1800 RPM. You state that at 2500-3000 RPM you can unplug the bottom coils without any difference. That is not normal. There is an important "syncing" procedure for the carburetors which is described in the Mercury service manual. I would start with that procedure. It is also essential when removing and installing the engine cover that you do not accidentally disconnect the coil wires. There isn't much clearance and the cover is quite heavy.

 

[bobbyc]

Forgot to mention...be sure the carburetor linkage to the bottom two carbs was not accidentally disconnected.

 

[faztbullet]

You state that at 2500-3000 RPM you can unplug the bottom coils without any difference. That is not normal.

On a hose it is normal...there is not enough load to bring the carbs in