Have to pump throttle- then she takes right off??

[Bill Collector]

I have a 1987 Merc 115 running on premix. I have to pump the throttle so the fuel system gains pressure and then the boat takes right off. I ski a lot so the hole shot is way important. Here's what I've done so far-
New bulb (replaced it 3 times thinking that was it)
Rebuilt fuel pump
New water pump
New water jacket gasket/head gasket
New stator, new coils, new switch box

So the thing runs awesome but I have to pump the throttle. I've tried to pump the bulb while it's running and I don't see a change. I also pumped it yesterday and watched the carbs to see if there were any leaks and there was a bit of fuel dripping out of the throat of each carb when it was under pressure (normal I would think) The bulb will lose pressure if I shut the boat off for about 15 minutes or more. I don't know where to start. Is it from the tank to the bulb or bulb to the engine? I disconnected the bulb from the motor and pumped it up and it pressurized. WHat tests can I do to narrow this down?

 

[Barnacle_Bill]

Re: Have to pump throttle- then she takes right off??

It sound like you have some trash in your needle and seat(s) keeping them from functioning properly. You might try adding some Sea Foam to the gas and if your lucky it may clear it up. If not the carbs will have to be disassembled and cleaned. Then reassembeled using new needle and seats and new gaskets.

 

[gss036]

Re: Have to pump throttle- then she takes right off??

Do you have a water/fuel seperating filter? Maybe full of water. Try runng a portable fuel tank to see if that matters.
I think bhile is right on w/ his diagnosis. I would try SeaFoam before tearing them apart. May be try draining the float bowls.