Lose of Power in Fwd

[MarkW]

On the way back from Catalina while motoring for a long time I notice a hesitation in the motor as if it was losing power. I immediately suspected it was a fuel problem so I changed the fuel filter. We started the motor again after sailing for a while and the power lose started again. The RPM's did not drop off dramatically, but you feel the engine losing power. We lost about a quarter of a knot in speed. The engine temperature did not change or increase. I had the mixing elbow replaced last year. The engine runs fine out of gear and in reverse. It only loses power when it's in forward at about 2700 - 2900 RPM. Has anyone experienced something similar? Does anyone know what might be causing the lose in power?

 

[Richard Deep]

Fuel Tank??

My first thought would have been build-up in the mixing elbow, but since you changed it recently, here's my second thought.I have seen similar problems when the fuel intake in the tank becomes clogged. I don't know when the last time you checked what's on the bottom of your fuel tank, but it's likely there's some crud down there. After a 26 mile trip across to Catalina, the stuff starts to slosh around. Some of it gets sucked up against the intake line. Not small enough to get through and show up in the filter, and not big enough to completely block the line, but enough to cause a loss of power at high rpms.When you shut the engine down, it all settles back to the bottom, and things run fine until the next time you get enough motion to stir it up again.You don't notice it in reverse or neutral because you're not putting as much load on the engine (thus calling for less fuel flow).- RichardS/V DiscoverySan Francisco

 

[Mac Lindsay]

screen!

Mark; There is a small screen on the bottom of the fuel pick up tube inside the fuel tank. This screen gets clogged from any sediment in the tank and reduces the flow. I had that problem on my 1984 H31 years ago and a mechanic told me to take the screen off of the pick up tube and throw it out. It only causes problems as you are probably experiencing. You should have a fuel filter between the fuel tank and the engine which is easier to clean in a seaway if needed. Mac.

 

[MarkW]

Fuel Pump

Thanks for your suggestions. I went to the boat yesterday and tested the motor again. I noticed now that the electric fuel pump runs continuously. Normally it runs breifly to charge the system and then as needed. Now it runs all the time. I am now thinking I have a torn diaphram in the pump or the pump is bad. I also had the fuel and tank filtered and cleaned 2 years ago.