115 running out of fuel ?

[crane]

I have a 1976 115 merc 6 stac on a 18' Reinell. I just switched from a 21" pitch prop to a 17" and saw a very good increase from 28mph to 35 with much less plane time. <br />Now I have a new problem, after a couple days the boat has now started to bog a few seconds after getting up to plane. I have recently rebuilt the fuel pump and flushed out the tank.the bulb seems to get soft and it helps when you pump it as it's starving for fuel. Also if I hold the fuel line in my hand while the motor is at an idle I can feel a strong pulsing at the line on both sides of the bulb. Any help would be appreciated.

 

[corm]

Re: 115 running out of fuel ?

Hi Crane,<br />If you can feel the bulb pulse then you may have a bad check valve in the pump. More than likely<br />you have a vacume air leak between the motor connector and the pick up tube in the tank. If you have a vac-pressure gage the fuel pump should draw 1 lb of vacume at the pump and produces about 6 lbs of pressure at the output to the carbs.

 

[crane]

Re: 115 running out of fuel ?

thanks corm i will do those checks