help with 9.9 evinrude - not planing

[mkirby57]

I just bought a pretty old 9.9 evinrude on a 16ft john boat and the first time i took it out it would idle ok but when i opened up the throttle the rpms would jump up and back down. At full throttle it was not running consistent and not going as fast as i think it could. I really do not know alot about motors so any help at all would be very useful. thank you

 

[tashasdaddy]

Re: help with 9.9 evinrude - not planing

really need model #. http://forums.iboats.com/showthread.php?t=158086

 

[steelespike]

Re: help with 9.9 evinrude - not planing

Is it running on both cylinders.How is the compression.If it is a bare bones Jon unless your really heavy it should plane at 18 to 20 mph.Might require gas tank all the way forward.

 

[mkirby57]

Re: help with 9.9 evinrude - not planing

hey guys thanks for your help but what do you mean by the gas tank all the way forward and how do you check compression?

 

[tashasdaddy]

Re: help with 9.9 evinrude - not planing

placing the gas tank in the front of the boat. you have to balance the load. with all the wait in the tail, all it will do is stand bow up. you take a screw in compression tester, remove spark plugs, insert the tester, pull rope like starting, about 6 times, and get the reading off the guage. repeat of the other cylinder, report findings back here.

you still have not told us the model number of the motor. without full info, you do not get full accurate help.

 

[mkirby57]

Re: help with 9.9 evinrude - not planing

i dont know the year but the model # is 10524c and serial # is e0004331 and also where can I get a compression tester? thanks

 

[tashasdaddy]

Re: help with 9.9 evinrude - not planing

motor is 1975, you can get a screw in compression tester at any auto parts store. ask around a friend may have one.

 

[mkirby57]

Re: help with 9.9 evinrude - not planing

ok thanks alot, ill give it a try

 

[iwombat]

Re: help with 9.9 evinrude - not planing

If it idles good in the water compression is more than likely not your problem. That said it's a very good idea to perform the check before dumping any money or time into repairs.

Maybe you can be a little more specific about "running inconsistent". Almost sounds like dirty main jets, but pretty tough to tell from your description.