25 Evinrude only allows 1/4 to 1/2 throttle?

[stephens.richard]

Just replaced the whole water pump, thermostat and gasket, and new spark plugs... motor still doing the same. Wont let me throttle more than 1/4 to 1/2. In neutral it is fine, but once in gear it sputters and pops and acts like its not getting fuel. What could be the cause of this?

 

[kfa4303]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

Have you ever had the motor at full throttle in the past? Are all of the mechanical throttle linkages working ok? There may be something impeding the rotation of the armature plate on the underside of the magneto. You may also need to rebuild or readjust the carb, if that hasn't been done in a while. This link should help.

http://forums.iboats.com/showthread.php?t=167352

Also, what is the compression on the motor? Should be over 60psi and within 10% of each other. These old motors can start and run surprisingly well on one cylinder. If the carb is ok. Make sure you're gettin good spark on each cylinder too. The spark should be able to jump a 1/4" gap wiht the points set at .020.

Sorry I know that sounds like a lot, but just trying to get as much info as possible. If you have good compression, good spark and good fuel, she'll run. Keep tinkering and let us know what you find. We'll get her runnin'. Good luck. Keep us posted.

 

[stephens.richard]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

Yes, the motor ran at full throttle not too long ago. Seemed like all this started when she started running hot and stopped peeing water; we changed the waterpump and thermostat for that issue. Now she's peeing and still bogging at full throttle. I figured on rebuilding the carb and checking compression also thought about making sure im getting spark on both cylinders...guess we got a little work to do. Time to get busy-- thanks for the help, keep ya posted.

 

[kfa4303]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

Good news is that she ran before, so hopefully she'll run again. If she really did run without water for some time, you may need to resurface and reinstall the head and gasket in case it became warped due to excess heat. Not too hard to do. Just need a flat surface and some 220 grit sandpaper. Lots of links here on how to resurface the engine head. Good luck.

 

[stephens.richard]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

Boy I sure would hate to think the heat did that much damage... i dont think so because I never ran it so hot it would cut off. But you never know! Hopefully its just the carb... here's to wishful thinking!

 

[stephens.richard]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

Up and runnin boys!! Thanks for the help! Just the wrong therm.--- check the simplest things first...what my dad always told me! ... amazing how little things like that will cause big probs. She runs like a scalded dog!! Thanks for all the help as always great information!!

 

[kfa4303]

Re: 25 Evinrude only allows 1/4 to 1/2 throttle?

sweet!