gas evaporating...spin the engine over 6-8 times, the pump the throttle several times, repeat till starts 1st time...

Same here...my understanding is that the bowls on the Weber's either drain or evap over time. I've read of a couple people giving one full throttle push to set the choke then bringing it back to low idle setting before cranking and having better luck. Never makes a difference with mine...I just keep feeding fuel and cranking until they finally fire...usually a good 20 cranks. :drink:

Mine either fires at no throttle or full throttle...nothing in-between...if she doesn't fire at idle I open her all the way n she fires every time

I have seen this problem many times and it is frustrating. As far as I know Mercruiser never had a good solution to the problem.

If it were my boat I would install an inline electric fuel pump out of a newer Mercruiser V6 or V8 (the cheap engines) that used the two barrel "Mercarb". These fuel pumps were mounted in the fuel line between the fuel/water filter and the carburetor. These cheap Mercruiser V6 and V8 engines started very easily.

Install the pump in the fuel line between your mechanical fuel pump and your Weber four barrel. This will prime the carburetor with the fuel sitting in the water/fuel filter. Connect it to an oil pressure switch and it will start to flow fuel to the carb as soon as the engines oil pressure comes up.

Do not use an EFI pump! They have too much fuel pressure! You must install an inline electric fuel pump designed for a carburetor with less than 6 PSI.

Dennis Moore