1973 85hp Chrysler Engine surges after 5-10 minutes running wide open

[trulyh8ful01]

what would cause my motor to run awesome for 5-10 minutes the all of a sudden start surging and lose and gain power at full throttle after awhile of that it just shuts down. It fires right back and acts as if nothing happened but will only run decent at about 3/4 trottle. But last time it did this it would start and idle great but as soon as I put it in gear it dies, does that for 10 or so times then takes off and runs good again. the last time I pulled the boat out I noticed this and wonder wehat is causing it too. See pic did I mention this is my first boat and nobody will work on it. if the picture didnt work there is a hole jus under the fill plug in the lower unit and I have what appears to be oil coming out of it

 

[jerryjerry05]

Re: 1973 85hp Chrysler Engine surges after 5-10 minutes running wide open

The gunk on the side is probably unburned oil/gas that leaked down from the carbs.
The surging:could be the tank vent is clogged or a hose is mushy and collapsing.
The fuel pump needs rebuilding.
Dying when put in gear:idle too low.750-800 in gear.About 1100 in neutral.