7.4 mercruiser bouncing idle, poor performance

[tcooke]

Hey guys, I have a 1996 7.4l mercruiser mag, bravo one drive Webber 4 bbl carb and a thunderbolt 5 ignition. Boat was running fine back in March, took it ou last week and she was barely running. First it won't hold a low idle, when it does it bounces up then down then eventually dies. It also won't plane, I get about 2000 rpm max at full throttle. I took the carb off when I got back and noticed one of the bowls was gummed up (coagulated gas and water??) after cleaning the carb and putting it back together with a new fuel water filter and pumping out about 30L from the tank in case there was water in there I am having the same problem.

Any ideas?

 

[alldodge]

Did you flush out the lines and fuel pump between filter housing and carb?
Also have you check fuel pressure (4 to 7 psi)?

 

[NHGuy]

Agree with AD, plus verify or reset your timing and idle with the TB V module in lock mode. You lock it out by grounding the purple & white wire while setting the timing and idle.