Compression

[Molska]

So i have a 1980 25hp Evinrude that hasn't been running to spectacular as of late, but what does compression tell me? The compression in the cylinders are 120 psi in the top and 119 in the bottom one. If i needed to replace one of them would these #'s be off or do i need to look at something else?

 

[Whoopbass]

Re: Compression

Those #'s are spot on for your motor. Your problem is definitely something else. Start off simple like replacing the plugs or cleaning out the carb and see if that helps.

 

[levi_tsk]

Re: Compression

agreed

 

[5150abf]

Re: Compression

you have compression, check spark, if that is there it leaves fuel as the culprit so correctly cleaning the carb should help, also a good decarb will aso help it run a little better but your comp numbers are perfect.

 

[etracer68]

Re: Compression

The compression tells you that, your motor internal parts are good, and head gaskets. We would need more info on how it is running, and what its doing that you dont like, to give more info. Most times its a carb or fuel issue. And as others have said, your comp numbers look great.

 

[Molska]

Re: Compression

So my 25Hp acts like this johnson 50 http://www.youtube.com/watch?v=DKbWcw2JRY8 so this is what i've done so far to the engine:

-Changed the spark plugs i do have spark
-New fuel tank and hose mixed the gas 50:1 might go 55:1 next time
-changed both coils
-did a carb kit
-new impeller
-checked the fuel line=clean as a whistle
-like i staed before did compression check upper chamber 120psi lower 119psi
- So the one of the only things i haven't changed was the power pack and the water pump but water is pissing out fine.

So any sugestions?

 

[levi_tsk]

Re: Compression

did you replace the core plugs when you rebuilt the carb ? also did you soak it overnight in carb dip and blow all the passages out with compressed air? a simple spraydown with a can of carb cleaner isnt enough on a two stroke carb because the passages are so tiny that the smallest speck of goop will greatly affect performance

and that video shows that a high speed orifice is clogged up(in the carb) NEVER AND I DO MEAN NEVER do that to your motor it can and will cause major engine damage from fuel starvation and lack of oil(remember that the fuel carries the oil that lubes ALL your internal engine parts

 

[Molska]

Re: Compression

Yup i did all that and even brought it in and a tech looked it over even set my float is its good to go

 

[levi_tsk]

Re: Compression

does this one have fixed jets? if so did you remove those and blow them out and soak em?

have you tried pumping the primer bulb while its doing that? if that makes it pick up its a fuel pump problem and you can rebuild it for about 20 bux

how about using the choke? if that helps the problem is in the carb

if its doing what that engine is, its running lean so it almost has to be a fuel problem however make sure your spark will jump a 7/16" gap use an adjustable gap tester like you get from any auto parts house theyre about 6 bux

 

[Molska]

Re: Compression

Ya i did all of that on the lake and the problem still percists. I haven't done the gap test i will here soon. So if it doesn't jump than what does that indicate and what needs to be done?

 

[levi_tsk]

Re: Compression

depends those power pack are notorious for failing AFTER the engine warms up and once it cools down it will test just fine same with the coils so make sure the engines warmed up before you test the compenents you need some special multi meter thingy to test the power pack but if you find its not sparking goo on one cylinder you can move the coil to the other cylinder and if the bad spark follows its the coil and if it stays in the same place its the power pack failing

 

[Molska]

Re: Compression

Yeah i did move the coils around and the engine still goes on one cylinder so i should go to the power pack? But still test spark?

 

[rtek816]

Re: Compression

My opinion is it is the power pack that is failing. It's hit and miss on all cylinders. Not a coil, not starved for fuel.

 

[Whoopbass]

Re: Compression

The guy that made the video states the power pack was the problem so I would start there. You can probably get a used one pretty cheap on ebay.

 

[levi_tsk]

Re: Compression

i wouldnt
- suck it up and buy a NEW mallory from iboats if your gonna get one you get a 2 year waranty and if you wanted to splurge buy a CDI with the 3 year warranty I NEVER BUY USED ELECTRONICS
ESPECIALLY on ebay

 

[Molska]

Re: Compression

Okay so after all of this replacing parts new tank hose blah blah blah.....IT WAS THE POWER PACK!! But now it takes even more effort to start my engine and every time i need to restart i have to choke it, a problem i never had before. I went from 3-5 pulls on cold start to 15+ and from 1 pull on restart to re-choking and 3-5 pulls. What do i need to re-adjust?