1991 force mercury won't start in water

[Mattk219]

OK I have a 1991 force mercury motor I know there not the most popular but it's what I have my question is the motor starts and runs great out of water but as soon as I drop the motor in it dies and or won't start some times it will start for about 10 seconds then die if I squeeze the primer bulb every time the water pump is working has new plugs exhaust boot fule lines and just had lower end serviced last month

 

[HydroGeek]

OK... I'm no pro, but here is my guess. One or more of the floats in your carbs are messed up. Try putting it in the water, and running the trim all the way down/starting and then part of the way up / starting (keep the lower unit water intake in the water) and see if one works better than the other. Do the same thing when on dry ground too. Adjust the trim and see if that causes the problem on land.

Some other questions... is the vent on your tank working correctly? Does the bulb collapse when running?

 

[Jiggz]

Troubleshoot while in the water. Make sure you describe it succinctly what you did and what happens to each action you do.
1. With boat in water, remove top cover or cowling and try starting. Does it starts?
2. If it starts, do you see exhaust smoke coming out of the powerhead? If yes, you have exhaust leaks that is preventing you from starting the engine while in the water.
3. If it did not start, is there fuel getting into the carbs? If none then the carb floats might need some adjustment.
4. If there is fuel getting into the carb, is there sparks on each spark plug while you crank it over?

 

[Mattk219]

Boat will start with trim up on down out of water I have fule l going to carbs and have spark the bulb stays firm when it's running when it's in the water it will some times run for about 10nsecounds then die and won't start agine floats seem ok since it start up or down out.of the water

 

[Mattk219]

OK some better new so I took the plastic intake off that covers the 3 carbs they looked clean but I sprayed some carb leaner in each one let it sit for maybe 3 house went out and it fired right up in water put in the back on fired up fine agine put cowl back on and it has started every time now does it make any since that just spraying the carbs a little made it work I'm kinda at a loss why it's working now

 

[Jiggz]

I say it it pure magic. However, if it is working I just leave it as it is.

 

[jerryjerry05]

You evidently cleaned something that was blocking the idle circuit.
Chevron puts out a fuel system cleaner.
Comes in a black or grey bottle.
It says Techron on the label.
I mix 1 bottle of this in 1 gal of gas and add the appropriate amount of oil.
Disconnect the fuel line and run this through the carbs.
Once it's burning only the new mix I shut it down and let it set 2-3 hrs.
Then rehook the old gas and go.

 

[Mattk219]

Thanks guys I'm going to try it agine after work and see if it fires right up agine I'll let every one know than you