mercruiser idles and dies

[spatera]

My son and I just bought this boat. It’s a 96 Bravo 200 4.3GS with rochester 2 barrel carb. The engine starts fine, idles about 1000 rpm then acts exactly like it’s running out of fuel and dies. I can pump the throttle once and it’ll start but cannot get it to run below 1000 rpm without it dying. As long as I pump the throttle it will run.
The fuel pump has a steady 12v going to it and about 13 psi of fuel pressure. The oil pressure does not drop too much at idle.

so far we’ve installed a new/rebuilt carb, new plugs wires cap and rotor and new fuel filter. When I put the new cap on I noticed the button looks a little past tdc but I can’t find the purple/white wire to put it in timing mode so i can check it.

We we bought the carb from fly. The air mixture screw was set at 4 turns but as stated, I can’t get it to idle in order to adjust.

Any ideas

 

[alldodge]

12v going to it and about 13 psi of fuel pressure

This is your issue, fuel pressure for a carb should not be more then about 7 psi, your flooding the motor

 

[Bondo]

The fuel pump has a steady 12v going to it and about 13 psi of fuel pressure. The oil pressure does not drop too much at idle.

Ayuh,..... Welcome Aboard,..... The pump should get 12v from the starter, when the starter is crankin',....

Once the motor starts, it's powered from the ignition circuit, through an oil pressure switch,...

Is this the stock pump,..?? As AD says, it should be more like 4 to 6 psi,....

and new fuel filter.

I don't suppose ya examined the Contents of the ole one, for anything but clean fresh gasoline,..??

 

[spatera]

Thanks for the reply’s. Everything seems to be ok as far as voltage to the pump. We checked it during start and while running and all’s good there. I also thought that electric pump was too much pressure and rigged a Holly fuel pump 4-5 psi and still have the same problem. Even with stock pump I never saw fuel coming out of the overflow.

 

[alldodge]

Your either getting to much or to little fuel, since your not seeing overflow then maybe not enough. Not going to bother with fuel pressure since you checked it at the carb inlet with a Tee fitting.

Have you done a compression test?

 

[spatera]

That’s my next move if it’ll stop raining.