[ky_pits]

I have a 1974 25 hp evinrude that has had a complete tune-up(plugs,points,carb rebuild,fuel pump)even new coils.The problem is it will start and run fine idling and at full throttle,but after being full throttle for any period of time and you try to idle back down it will die,dead in the water..I can pull and pull but it will fire but die,I wait a while and it will start and run but cuts out unless its full throttle.It acts like it is losing a cylinder sometimes while idling....Any help would be great and yes I have a manual Thanks

[DJ]

Do you have spark, when it won't fire?If so, it could be a plugged circuit in the idle side of the carburetor.

[ky_pits]

Yes i have spark because it will try to hit.Just wont start.If its in the idle circuit then why does it idle fine when i first take it out before it has run full throttle.I dont understand it?It acts like it runs out of gas.I set the float level to specs(parallel to gasket surface)when the carb was rebuilt and all the passages were blown out with air hose.

[fireman57]

You say you have spark because it wants to hit. you may not have spark on both cylinders due to a coil heating up and breaking down. Next time it does this check for a bright blue spark on both plugs. If you have yellow or orange it is not enough. Clean your grounds and connections on them and try again.

[ky_pits]

both coils are new and grounds are clean.It seems to be fuel related,my primer bulb does not stay firm like it should.I have cleaned the carb but maybe missed something.When it does this it acts like its losing a cylinder but dount know why.

[fireman57]

Consider changing your fuel line. There are orings and check valves in it that may have gone bad. Did you check your float and make sure that you blew all the passages out with air? It only takes a small piece of crud to cause problems.

[Crappie_Fan]

I have the same motor and have had similar problems with air leaking into fuel line, where the hose clamps to the bulb. Those cheap crimp clamps that come on the hose are not good enough. This will also help with the bulb getting and staying hard. Just a place to start.