Top end on a 76' Evinrude 25 hp model # 25602E

[RRH31978]

Motor idles great no problems starting, seems to fall flat after running 3/4 to full throttle for like one minute or less. Thought it was the carburetor so I used some carb and choke cleaner on the outside but still has same issue. I am pretty handy and will attempt anything and I guess I am thinking of rebuilding the carb!!!!!!! The previous owner said he has already put a fuel pump on it, and seems to think it is the high end jet fouled.

How hard is it to rebuild the carb??????

How do I check the compression in the cylinders??????


What else can I do??????

 

[jimmbo]

When the engine falls flat, has the primer bulb collapsed? Try running with the cap tank cap loose so Air can get in.

As for the questions

Depends on your mechanical skill and discipline. Those carbs are simple, but some checks and possibly adjustments to the carbs sync with the spark timing is often in order upon reassembly

Use a compression gauge

Get the correct Factory Service Manual

 

[RRH31978]

Thanks for answering so quickly Jimmbo!

The tank is ventilation is good and the primer bulb is remaining stiff! I probably should have mentioned that earlier. Thanks I just don"t want to get in over my head and make it a bigger problem!

 

[F_R]

The high speed jet is deep in the hole behind the hex drain plug on the carburetor. Easy enough to remove and inspect without taking the carburetor off or apart------IF you have the proper special screwdriver. It also is easy to mess it up with makeshift screwdrivers, possibly to the point that you will never get it out.

Meanwhile, remove that hex drain plug and look at the inner end. It should be shiny bright clean. If it is coated with any varnish or shellac substance, you can expect the jet behind it is also fouled and the carb needs to be cleaned and a rebuild kit.

 

[David Young]

lots of youtube videos on how to rebuild the carbs. Here is one but many more https://youtu.be/uF3CWVfcbaw

 

[RRH31978]

Well in the process of taking the carb off the hose going to the fuel pump split i tried to trim it down and reinsert it but it split again any one know what size it is I am thinking 5/16.

Now that I have the carb off i plan on rebuilding it and I will be sure to check and see if I can remove (carefully) and clean the high end screw.

Thanks a lot for all the help I am learning as we go here! LOL!

 

[Crosbyman]

that " high end screw" is for the idle drip chamber on top...under the dime size plug


the HIGH speed jet is in the bottom of the carb behind the screw plug (bolt)

utube has lots of videos for you

 

[oldboat1]

Take the old fuel line in with you to an auto parts store, and see if you can get a match with their fuel hose (inside diameter). When an old line behaves like you describe, it's rotted away -- may be your running problem. It would be a good idea to replace the other hoses as well.

 

[RRH31978]

Well i think i did pretty good! It's running and idling very good. Didn't go full throttle in the trash can it is a little flimsy!

 

[RRH31978]

Yeah changed all the fuel lines and rebuild the carb seems ok for now. The real test will be on the lake for the top end.

 

[oldboat1]

Well done!