Wont Power Under Load

[BigSteve1967]

1989 Mercruiser 5.0 GM based 305 with a Alpha One Outdrive

The engine will run perfect on the hose it idles great and even when revving it up it will rev up no problem it does the same when in the water it will idle great and rev up in neutral perfect BUT when I put it in gear it wont go above 2500-2800 RPMs and wont plane, once in awhile it will actually get up to 3000 rpm and get up on plane then it seems to run ok not perfect but ok and to get it to get up on plane takes it awhile it will sort of creep up to about 3000 rpm and sometimes it wont, I have also noticed that after I have run it awhile either if it gets on plane or doesnt and I get to where I am going I will shut it off and anchor awile to swim or whatever but when I go to start it up it is hard starting and I have to give it a few pumps then hold it full throttle to get it to start.

any help would be great.

thanks

Steve

 

[jerryjerry05]

Re: Wont Power Under Load

First thing to do is a compression test. Then a spark test.
It's possible that you have water in the fuel. Check filter.
When was the last tune-up? All the wires on? Is the flame arrester blocked?
Check air vent line for mud daubers,kinks any obstructions. Do these and get back.Jerry