3 problems...

[skyski_tige]

I had a 1997 2150 - I had the boat bog down and it was the fuel pump. I wasted a season messing with other fixes and nothing fixed it until I changed the pump out.

I changed the spark plugs every year and the wires every other year. I would clean the point on the distributor cap each year and usually replaced the cap about every 3 years.

Have you replaced your impeller?

[bagzzz]

I had a 1997 2150 - I had the boat bog down and it was the fuel pump. I wasted a season messing with other fixes and nothing fixed it until I changed the pump out.

I changed the spark plugs every year and the wires every other year. I would clean the point on the distributor cap each year and usually replaced the cap about every 3 years.

Have you replaced your impeller?

The previous owner replaced the impeller right before i bought it.

Good news - I found the problem. I took the whole fuel system apart and found a one-way valve on top of the fuel tank. This valve was stuck half way open. We blew it and crap came out (so to speak). I am pretty sure this stuck valve was the reason the boat was not getting enough gas. It is strange - this valve is not listed as a part in the MerCruiser manual.

I also changed the plugs and wires and that made a difference too. Next is the water pump. I thank everybody for their help!

[R&T Babich]

... found a one-way valve on top of the fuel tank. This valve was stuck half way open. We blew it and crap came out (so to speak). I am pretty sure this stuck valve was the reason the boat was not getting enough gas. It is strange - this valve is not listed as a part in the MerCruiser manual. ...

The anti-siphon valve in the tank pickup line is not a Mercruiser part.
(anti-siphon valve, 1/4” NPT x 3/8” hose barb, Tempo 260030 479ASV)
Lots of places sell them.
http://www.moellermarine.com/afterma...ystems/valves/
All tanks in our boats have these installed probably from the tank manufacturer.
It keeps fuel from siphoning thru the fuel line into the bilge if there is a leak.
I think there is a little spring loaded ball in there and it will close at very low flow rates.
The fuel pump will provide enough suction to open the valve and then at idle it will stay open.
With age the valves can get clogged or corroded.
In a pinch it could temporarily be replaced with an open fitting.
I just carry a spare.