1998 johnson 25hp runs only with choke

[Drewdaddy]

Ok I have a 1998 Johnson 25hp motor that only seems to idle and rev perfectly fine with the choke on. Now on my motor you pull the choke all the way out and I can hear it squirt, then it automatically pulls itself in almost all the way. I noticed there is a little red line on the choke pull where it stops on its way back in. If I leave the choke in that position the motor runs great. If I push it all the way back in, which is about a half an inch, the motor revs up for a few seconds (about 10) then dies out. I have changed the plugs, tried three gas cans and hoses, checked all lines for air leaks and taken the carb apart (it was clean) and blew out all the passages. Don't know if it matters, but the old plugs were covered in oil and kind of blackish brown. Also the psi was 120 #1 and 119 psi #2. Everything seems ok. I did notice that the carb looks like it has been hosed down with cleaner before I picked it up. Could that have caused the crud on the plugs? Like I said before, the choke sticks out maybe a half of an inch. The choke stops at that point by itself on the way back in after letting it go. Is the choke suppose to stay there??? I also forgot to mention that while it is running, if I pull the choke all the way out, the motor bogs down and shuts off like a normal motor would. So it is not like it needs the choke on full blast to stay running. I had this problem before when I can a carb that was gunked up, but again this one was clean as a whistle.

 

[Joe Reeves]

Re: 1998 johnson 25hp runs only with choke

If you didn't manually clean the high speed jet located in the center portion of the float chamber, do so.

 

[tashasdaddy]

Re: 1998 johnson 25hp runs only with choke

agree^^^ also read the TOP SECRET FILE.

part diagrams http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

 

[jbjennings]

Re: 1998 johnson 25hp runs only with choke

The red line position is for warm up only when it's cold outside. I don't even need it when it's warm outside. There is almost positively something clogged up in you carb. or not spotlessly clean, or you have a vacuum leak.
JBJ

 

[Drewdaddy]

Re: 1998 johnson 25hp runs only with choke

If you didn't manually clean the high speed jet located in the center portion of the float chamber, do so.

I am glad you mentioned this. The tube (high speed jet I assume) that was in the middle of the carb float had a needle in the middle of the tubing. Now the needle was not dead center in the middle of the jet. It almost seemed like it was bent to one side of the tube. Should it be dead center? This needle that stuck down into the carb bowl seemed like it was the needle that went all the way into the carb body behind the butterfly flap. I didn't mess with it as it seemed it had not been bent by accident, but looked as if it was to come that way. I hope I am making sense. Again it was a copper looking tube that dipped into the float bowl and was about the size of a writing pin shaft. Inside of the opening there was a needle about the same size as the lead on a number 2 pencil. The needle was not dead center in the tube but to one side. That just didn't seem right. What is the best way to manually clean the high speed jet? Can I take it out? If this is covered in the link provided I am sorry, I am about to go read it.

 

[Joe Reeves]

Re: 1998 johnson 25hp runs only with choke

You're speaking of the vertical high speed nozzle, not the high speed jet. Remove the screw from the front of the float chamber, directly behind that screw (near the center of the float chamber) in a horizontal position is the high speed jet.

 

[Drewdaddy]

Re: 1998 johnson 25hp runs only with choke

You're speaking of the vertical high speed nozzle, not the high speed jet. Remove the screw from the front of the float chamber, directly behind that screw (near the center of the float chamber) in a horizontal position is the high speed jet.

Thanks, i will try that tomorrow. Is this the screw that in "adjusting carbs" suggest to put it back in and then back out about 1 turn or so? Or do I seat this screw all the way back down after cleaning?

 

[seakingbob]

Re: 1998 johnson 25hp runs only with choke

I just did my carbs on a 40hp.When i took them apart the the need valve was bent also.When I did the other carbs it was the same way.I left it alone and when I was done cleaning and put it back together it run great.Leave the middle needle valve alone.

 

[Drewdaddy]

Re: 1998 johnson 25hp runs only with choke

Got it figured out.. Thought I would share in case some one else is in the same boat (pun intended). Turns out only one of my fuel lines was starting to rot and break up on one little section of it. The inside of the hose had turned to mush and was just oozing out of the hose. So another good carb cleaning and all fresh new fuel lines has seemed to solve the problem. Thanks for all the info.