Loosing primerv bulb pressure at ball and lost high speed.

I bought a 1972 65 hp johnson on ebay last week and put my 65 hp evinrude lower unit on it. The motor looked pretty clean and was running very well for about two hours . It idled great and had plenty of power. Then I noticed a slight loss in power but it was rectified by throttling. On the way in I lost all my high speed. I noticed the primer bulb was low and when i pumped it up it wouldnt stay hard and the boat stayed at max 10 knots. I'm wondering if the fuel pump may be bad or if dirty carbs could cause the ball pressure to drop. My tank is new and so is the ball and tank fitting. If I do clean the carbs up, I'm affraid to mess with the low speed needle. Everything was running so good i'm affraid the mess it up. Is it likely that the carbs are dirty if the motor ran flawlessly for the first hour? I have a spare set of rebuilt carbs from my other motor but the adjustments are all out of whack on them. They are clean though. Anyone know what the low speed needles should be set at for a 72 3 cyl Johnson. Can the low speed needles and those seats be removed for cleaning and damaging the seats or is it better to change the seats altogether. S-inc-e- -nmy problem is a fuel starving problem and not a low spped problem should <br />I just clean the float bowls and main jets. Thanks

Re: Loosing primerv bulb pressure at ball and lost high speed.

Your carbs wont cause a flat primer bulb. Check to be sure tank vent is open.<br /><br /> If your primer bulb was sucked down flat it shows your fuel pump is working its butt off tryin to suck fuel.<br /><br />Primer bulb will not stay pumped up while motor is running. Because needle and seat,s are letting fuel pass through constantly.<br /><br />If you notice an increase in RPMS while pumping bulb by hand it indicates poor fuel pump pressure.<br /><br />Dont mess with carbs just yet. work on fuel delivery to carbs first.<br /><br />Good luck!

Re: Loosing primerv bulb pressure at ball and lost high speed.

There was no increase in rpms with almost full throttle while squeezing the ball. Tank is new and vent was open but I quess I should have switched tanks anyway. Thank You. I'll put the fuel pump from my motor on and switch the tanks. Thank You. This forum is such a great help to me.

Re: Loosing primerv bulb pressure at ball and lost high speed.

It sounds too simple to say, but it looks as though you may have picked up some crud during the change over, and this has found its way to your carbs.<br /><br />As Goodoleboy says, the fuel pump seems to be working. You didn't say the primer bulb was flat - you said it was low. Bulbs aften run 'low', but not flat. If it's running flat, which I doubt, you have a fuel supply problem - which is quicker and easier to fix than the carbs. <br /><br />That needs confirming before you go any further.