Mercury 150HP losing power at WOT

C

capevt

Cadet
Joined
Aug 10, 2011
Messages
6
:facepalm: Hello,

I have a 2001 Merc 150, carb'd engine. Last year it received a new power head which included a fuel pump rebuild and carb clean out.

Just a few weeks ago it started to have issues. When running >4k rpm it will lose power, like it is starved for fuel. I have replaced fuel lines, plugs and the Racor. Yesterday I pulled the fuel pick up - no cracks and the screen looked new. The barb off the pick up was a regular brass barb and had no anti siphon check ball.

I ran it with an external tank (by myself so a little tricky) going direct to the engine, not thru the Racor. It seemed as though I couldn't pump the bulb quick enough at WOT and it would die out. I can idle for a few minutes, pump the bulb up and it will go to 5500 for about 15 secs then lose power.

Next step is the fuel pump?? It probably only has 50 hours on it so I'm not confident that it will be my solution.

Thanks for any help!!
 
U

ufm82

Master Chief Petty Officer
Joined
Jul 29, 2003
Messages
827
Re: Mercury 150HP losing power at WOT

Did you do the fp rebuild? Maybe you didn't get something right. Not pointing any fingers of course but since it runs the same on the boat's tank and on your test tank that eliminates the external fuel system. So you are left with the fuel delivery system to the carbs and that would be the pump. Check the lines from the external fitting on the engine to the pump and make sure they aren't pinched/collapsed. Ditto on lines from pump to carbs.

Are you certain all parts were installed properly. I don't know the 150 pump off the top of my head but I've seen diaphragms in backwards, missing gaskets, etc. At WOT your engine is using the most fuel at any other time. Anything that limits the flow is bad obviously.

Sure sounds like a pump issue to me.
 
C

capevt

Cadet
Joined
Aug 10, 2011
Messages
6
Re: Mercury 150HP losing power at WOT

The engine work has all been performed by a Mercury mechanic. He told me that he did not believe it was the fp which is why I pulled the pick up. I'll prob rebuild it myself and see what happens - it's very accessible.

Thank you for the reply.
 
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