Donzi26ZX

I am trying to figure out what is wrong a few weeks ago I went over to LI and my 1999 330 SS with twin 7.4's ran perfect as it has in the past years. On the way home I started the boat up and idled out of the harbor, I put the boat up on plane and it took off then the starbord tach started to bounce and then it dropped to like 1000 RPM's and then i brough the throttles back down. It would stall and then I would start it again and I would get another blast out of it where the boat would plane off and then in about 10 seconds the RPM's would bounce once again and do it all over again. It seemed like a fuel problem and the other motor ran fine so I decided to switch the filter, and then neither motor would run. I then switched the filters back and after a while I finally got one started and just got the boat home. I went and bought new filters and changed them, the port motor runs fine now and the starboard motor won't start. I took off the fuel filter and there is nothing in it so I filled it with fuel and it still won't start, any suggestions please?????? I turn the key and can hear the fuel pump turn on and run for a second, priming the motor. I am thinking fuel pump or cool fuel???? If so where is the fuel pump located on the 7.4???? Thanks for any help.

FOUNTAINATLAST

Find the port for checking your fuel pressure, depress that valve a few times inbetween priming the pump. There is most likely air trapped in the fuel system and the merc pump is having a hard time getting it primed and fuel to the injection.

Donzi26ZX

Thanks, I replaced the fuel pump today, works perfect.