1975 evinrude 25hp runs but needs help

[blue jon boat]

I have just purchased a 25 hp 1975 evinrude with electric start and a long shaft kit i took it out on the lake the other day and it was hard to start i tried choke no choke and any other combo finally it started it took it around the lake it ran good a full throttle and part throttle but it would not idle i have noticed the fuel tank seems to be pressurized but it is a single line system is that normal? or should it be vented for this motor
I also have a question about water flow there are two holes on the back below the cowl they seem to have exhaust with water blowing out and i don't see a tell-tale is a heavy mist or splatter normal out of these?
after i warmed it up and i killed it a few times it still seemed to be hard to get started and also i would like to know if it has a thermostat if so what temp does it open
Thanks for any help

 

[robert53a]

Re: 1975 evinrude 25hp runs but needs help

Hi, it sound like a dirty carb. Cleaning and kitting the thing will probally get you satisfaction. Also get your self a manual, the trouble shooting section will be of infinate help. The 75 doen't have a tell tale they didn't start coming out till 76. To tell if your water pump is working watch the upper two exaust holes and see if it sprays out water. If it does the pump is working....Robert

 

[catalyst-519]

Re: 1975 evinrude 25hp runs but needs help

After your decarb and kit I'd test the spark. I had trouble with my 76' 9.9 misfiring and then dying after reaching operating temp. After it would sit for 20min it would start up again and do the same thing after a while.

These older models still run on a magneto. I changed the condensers, and the exciter coil. Brought it to the mechanic to have the points set though as I'd never done it and didn't want to mess around with timing. Spark problem was fixed after this. The idea is that the older coils and condensers can fail and short out if too hot.

Hope this helps


Cheers---519

 

[blue jon boat]

Re: 1975 evinrude 25hp runs but needs help

hey thanks for the help i think i will give it a tune up and a carb kit i do have a manual but it give allot of variables i have another questoin i forgot to ask is there a kill switch or is it supposed to die when you cut the throttle to idle

Thanks for the input

 

[tashasdaddy]

Re: 1975 evinrude 25hp runs but needs help

cut throttle. kill switches did come till the 80's. although you can add one for safety.

 

[blue jon boat]

Re: 1975 evinrude 25hp runs but needs help

The fuel tank seems to build pressure when setting out in the sun and the cap doesn't seem to have a vent is this normal for a single line system it is an old metal tank but it looks to be in good shape an no rust inside

Thanks for all the help

 

[Relliott]

Re: 1975 evinrude 25hp runs but needs help

The same thing happens with my plastic tank. It is just the heat adding pressure inside the tank. I would try not to store the tank in direct sunlight.