Evinrude 25 HP intermit no full throttle

[allyrunner]

My 1989 25 HP Evinrude has an intermittent problem with running
at full throttle. It will run at low speeds during the problem. If I throttle down a few times, then it can clear it and run at full throttle again. Its is a carb issue, but not sure where. I was looking for a High speed jet to clean, but it only has a low speed jet.
I suspect its a piece of dirt that is intermittently blocking something in the carb.
The bowl has been flushed, but it still occurs.
Any thoughts would be appreciated.

 

[dew2]

Re: Evinrude 25 HP intermit no full throttle

On this parts list clean part#22 http://www.crowleymarine.com/johnson-evinrude/parts/46838.cfm

 

[Taylorsville]

Re: Evinrude 25 HP intermit no full throttle

Keep us posted on this I would like to hear what the prob was.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

thanks for input....
That is the correct carb and part according to my model #
CE25 ELCEB
but on my carb that is the drain plug for the bowl.
unless the orientation of the pic is misleading.
The screw for this part number should be visble below the air intake and
at the bottom of the bowl.
Am I looking t this wrong...?
thx

p.s.
I will update thread when I find it...
I think problem was caused from my cowling insulation breaking down and turning to dust particles.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

okay, its behind the drain plug, or the nipple as illustrated on parts list.
I was able to loosen it, but I need a shorter screwdriver to remove it.
3/16th and less than 2" long.
Will update later.
thx

 

[dew2]

Re: Evinrude 25 HP intermit no full throttle

If I'm not mistaken that screwdriver is a special driver.A wide blade thats thick.A normal screwdriver may work but dont force it.Grinding a flatblade down to make it thicker is best.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

okay, I will look into getting a proper screwdriver...
i was wondering what size of hole is on this part?
Can we clean it out with a wire or paperclip?
and if the dirt wasn't in the hole, then I guess it would likely
be on the other side of the orfice plug???
It feels like a piece of dirt is intermittently blocking the flow...

 

[Cofe]

Re: Evinrude 25 HP intermit no full throttle

Just leave it in place, and use a bread tie with the plastic removed to poke in the jet. I keep several bread ties on the boat in my tool kit just in case.....

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

I ended up removing the orfice plug to be sure.
It was clean, but I was wondering if there was dirt on the far (gas line)
side that was intermittently blocking the flow.
I flushed the line and we will see how it goes....
The orfice plug appears to allow gas into the bowl.
I am trying to understand how it works.
How does it control the flow of gas, other than filling the bowl....
or is that it?
thx

 

[Cofe]

Re: Evinrude 25 HP intermit no full throttle

The float needle valve is what fills the bowl with gas in the carb.
The motor suction draws air through the carb creating a vacuum on the venturi tubes, which draw fuel from the high speed orifice. Hope this clears things up for you....

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

Thanks,
It appeared that the gas flow was directed into the bottom of the bowl or straight through to the
drain plug, which didn't make sense.
So far so good with the flushing of the line, but this weekend will be the test....
Hoping it was dirt on the gas line side that was problem....

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

Well, I still have the problem...
either the engine is starved for gas on take off or
after full throttle after a period of time.
It doesn't stall, but I have to put it into neutral and try a few times
and then it goes ok....for a bit...could go 10 mins
or a few hours over 2 days...
Is there anything else I can check beyond the orfice plug?
thx

 

[fireman57]

Re: Evinrude 25 HP intermit no full throttle

When is does this pump the primer bulb and see if it picks up. If it does you probably have a small tear in the fuel pump diaphram that allows it get enough fuel a lower speeds and not enough at higher. When it runs right it may be that the tear pulls back together for a little while to let it run. Just a thought but if it still does it then you know it is not the fuel pump. One other thing, make sure your gas tank is vented or it can't pull enough fuel.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

thanks...
I previously have tried to prime the bulb without any change...The Bulb is also hard when this problem occurs..
The tank is also vented, I even tried loosening the cap off to be sure...Tank was totally cleaned and inspected....
I previously used compressed air on the line to the carb. There was a blockage and it cleared, probably at the orfice plug. Is there a
possibility that it could have blown dirt into the venturi tubes that could be causing an intermittent problem?

 

[fireman57]

Re: Evinrude 25 HP intermit no full throttle

Could be but if you had flow there it usually pushes it on through.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

are there any other thoughts on what to check...
I could take off the carb to clean, or even take it in for service,
but this type of intermittent problem could be difficult
to chase...

 

[fireman57]

Re: Evinrude 25 HP intermit no full throttle

the only other thing that could cause this would be a weak coil that fails under a load. You might take a buddy and a timing light next time. You run the boat and he watches the light to make sure it keeps flashing so you know that you are not losing spark to either cylinder. Sometimes the coils do funny things.

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

I will give that a try.....
thanks..

 

[robert53a]

Re: Evinrude 25 HP intermit no full throttle

Hi this similar to a problem I had with a 1991 Evinrude 25. It would run good for 5 minutes and then bog down like it was running on only one cylinder. i would shut it off and fiddlle with it for a while, try to start it and it would run fine for a few minutes and do it again. What was happening was the thermostat was stuck shut and it got hot and went into limp mode. A change of the stat and water passage clean out solve the problem. Check you temp......

 

[allyrunner]

Re: Evinrude 25 HP intermit no full throttle

well, it appears it is ignition. I tested both coils and they both appeared to fail, but one was significantly worse...
Since both coils appear to be failing, could the problem be in the power pack ?
I has a problem with a 75HP Evirude power pack a few years back with intermittent failure, but I didn't think that was the problem this time. hmmm heres for not thinking....
So, do I replace both coils, or could the power pack cause this problem on this engine.
thx