1990 350 Mercruiser barely starts intermittantly

by Mike
(Oregonia, Ohio, USA)

I have a 1990 Bayliner with a 350 and a QuadraJet Carb. It runs great at times, but at other times I cant even get it off the trailer. I have learned the only way it will start when it is acting up is at WOT and feather the idle once it starts to fire. When this happens the carb floods and it runs horrible until the either the voltage climbs from 12 volts and it clears up, or it clears up and allows the voltage to increase to 13-14 volts.

I have had the carb off and completly rebuilt. The plugs on the bottom of the carb are sealed tight and the float is the newer style.

The only oddity I have found is when the boat starts great, the voltage climbs right up after cranking. When the boat barely starts, the voltage is always right at 12 volts. It runs very rich, dumps fuel out of the accelorator pump until the gauge reads 13.6 volts.

This happens cold or after running great all day. I am getting better at starting it when this happens because i used to drain the batteries. Today, I thought we was going to be stranded and eventually got it running enough to put it in gear. Once it cleared up it ran great.

Thank you for reading, and thank you in advance for your suggestions.