Yamaha 150's-Excessive Fuel Burn on Port Engine

[Doc of the Bay]

I have twin 1996 Yamaha 150 Saltwater Series (Carbs) on my SeaCat. My port engine is burning at least three times as much fuel at idle than my starboard engine as per my Yamaha Fuel Management Gauges. At 3500 RPM, the starborad is burning about 8 GPH and the port is burning about 12 GPH. I also noticed at fill up the port tank took at least 8 more gallons than the starboard tank to fill up. I been told it is probably my fuel pump or pumps. The port engine misses slightly at idle, but other than that, it runs fine. There is a definite sheen on the water from the port engine. The way I understand, it is pretty simple to check the fuel pumps by unbolting them and pumping the bulb and if fuel leaks out the back of the pump, the diaphragm is bad. Any more advice would greatly be appreciated. I will be trouble shooting this weekend. Thanks in advance, Doc of the Bay

[jb123]

you still didnt check them ??? get on it !

[Doc of the Bay]

First thing in the morning JB, and I will let you know the outcome. I have been preoccupied with the oil slick threat down here on the Louisiana coast, Thanks again, Doc

[Doc of the Bay]

Thanks for the Help Guys

I unbolted both fuel pumps on the port engine and pumped the bulb. The bottom pump was not leaking any fuel from the back side at all, but, the top fuel pump was pouring fuel out of the back of the pump with every pump of the bulb. I ordered the pump from boats.net and will have it changed out as soon as the part arrives. Thanks for all the help. Doc of the Bay

[Doc of the Bay]

Received the fuel pump from boats.net and changed it out in less than 30 minutes. Very simple fix. Now my Yamaha fuel management gauges show the same GPH burn on port and starboard and no more sheen on the water. Thanks again for all the help, Doc

[rnast]

question on your yamaha

Say Doc of the bay

I was looking at a boat with a 1998 200 hp saltwater series on it and under the cowling I noticed some white on the gaskets between the heads and main block, should I be concerned

Thanks if you have the time

Rnast

[Doc of the Bay]

Good question, Rnast. It could be just mildew from moisture under the cover, or may point to a possible gasket leak issue. Ask the experts here on boats.net and they can give you a better answer. Thanks for asking, Doc