Carb Rebuilt now engine troubles 150hp

[Dave_T]

1988 Evinrude 150hp with 3 carburetors

I just rebuilt my carburetors for the first time.
Now it only seems to be running on 3 cylinders when idling.
The 3 cylinders on the starboard side (sitting in the boat facing foward, on the right) don't seem to be firing when I am idling. I can pull the plug wires off when idling and the rpm doesn't change at all. When I pull any of the spark plug wires off the other side, the rpm's drop and the engine dies. Is there something I could have done wrong when rebuilding the carburetors? I used a spark tester to check that all of the plugs were firing. It was my first time ever rebuilding carburetors and tried to follow the instructions in the manual I have, but the directions were pretty much a joke. I installed the new floats at the correct level and I cleaned out all the passages but everything looked brand new when I took it apart.
Thanks,
Dave

 

[petryshyn]

Re: Carb Rebuilt now engine troubles 150hp

How the compression?
Are the plug wires reversed?
Did you swap the plugs from bank to bank to see if the missfires follows the plug?

 

[Dave_T]

Re: Carb Rebuilt now engine troubles 150hp

I swapped the plug wires and it is still misfiring on the same cylinders.
I have not checked the compression but I know that those cylinders were firing before I rebuilt the carb.

 

[petryshyn]

Re: Carb Rebuilt now engine troubles 150hp

Did you swap and clean the plugs?

 

[Dave_T]

Re: Carb Rebuilt now engine troubles 150hp

The plugs are brand new.
Is there something in the carburetor that would allow the fuel to go to one cylinder and not the other or some type of synchronization adjustments between the two sides?

 

[petryshyn]

Re: Carb Rebuilt now engine troubles 150hp

While it is always possible you built in a problem into a carb when cleaning it, I have seen new plugs fowled or shorted by debree after some engine work was performed. Please remove, clean and swap plugs, then check if the missfire follows.

You must be certain of ignition before chasing another possiblity.

 

[Dave_T]

Re: Carb Rebuilt now engine troubles 150hp

Swapped plugs and wires and the engine is still not firing on those cylinders.

 

[seahorse5]

Re: Carb Rebuilt now engine troubles 150hp

One possibility is the shift interrupter switch on the engine's shift lever. If it is shorted, or there is stiffness in the linkage, the switch will trigger and cut out 3 cylinders.

The other possibilites are the pack and/or the stator under the flywheel.

Only testing with the correct tools and service manual will tell you the problem.

 

[Dave_T]

Re: Carb Rebuilt now engine troubles 150hp

I used an inline spark tester that goes between the plug wire and the spark plug to check spark. All of the cylinders are getting spark. Is there someway to adjust the fuel to certain cylinders? Or could something else be the problem?

 

[Dave_T]

Re: Carb Rebuilt now engine troubles 150hp

There is a fuel leak coming out from below the powerhead (boxed in yellow in attached picture). Could this be from a blown head gasket and the fuel is leaking out and that is why the cylinders are not running? It leaks even when the motor is down and running.

 

[ezeke]

Re: Carb Rebuilt now engine troubles 150hp

Start by taking the air silencer cover off the carburetors so that you can observe the throttle plates. They need to be perfectly synchronized to work properly so look to be sure that they are fully closed at idle position and that they move together perfectly as they advance to the WOT or horizontal position. If they do not, adjust the linkage between the carburetors so that they do.

The leak is probably from the drain hose between the intake manifold and the air silencer being left disconnected after the carburetor rebuild.

 

[petryshyn]

Re: Carb Rebuilt now engine troubles 150hp

Also, when you have the silencer cover off, squeeze the primer ball hard and see if any of the carbs are leaking fuel. Debree in the needle and seat would allow the carb to flood giving poor idle and a bad leak out the bottom....

 

[henrye718]

Re: Carb Rebuilt now engine troubles 150hp

Thats a big leak, did you replace the gaskets inbetween the manifold and the carbs with new ones. Maybe you got a wire or something caught inbetween that area as you were putting the carbs back on. You should be able to look from many angles and see if thats the case.

 

[petryshyn]

Re: Carb Rebuilt now engine troubles 150hp

One other thing.....is it possible you flipped the primer solenoid lever?