15hp high idle

[rodneym1965]

i have a 15hp evinrude that idles way to high. i recently removed the carb and cleaned it. the problem started after a few times out it would stall when idling and you would have to choke it to get it to stay running. it would run good wot but would have an intermittent idle problem so i replaced the lines and connectors that didn't help different tank still no difference so i took the carb off and cleaned it throughly now with the idle mixture screw set at 2 turns it runs great just idles to high when i turn the screw in (to about 1 1/2) it acts like its running out of gas. the only way i see to adjust idle is with the cam follower is this correct? and if this doesn't cure it what else could cause this? TIA

 

[crxess]

Re: 15hp high idle

Cam follower has a mark. At the mark, the throttle should just start to open. Below the mark Butterfly should be fully closed and idle normal. If the plate is sticking<not fully returning> it will high idle.

 

[Rick.]

Re: 15hp high idle

You never stated the year of your motor so this may or may not apply. Some have an idle speed knob on the port side for trolling purposes. If yours does, make sure it is turned back so it doesn't prevent the linkage from moving towards slow idle. You can really cause damage to the gears if your shifting with the motor revving too fast. Rick.

 

[rodneym1965]

Re: 15hp high idle

the model yr of this motor is 1988 i dont think it has the knob your talking about but i'll double check. as for the mark im assuming it is on the cam and not the cam follower? the plate that may be sticking is that the metal plate hooked to the cam? thanks for the reply's hope to figure this thing out

 

[crxess]

Re: 15hp high idle

Yes and yes

 

[rodneym1965]

Re: 15hp high idle

well tried it out after work last night still reving to high. i had the cam follower so it wasnt even touching the cam so that wasnt the problem.could i have an air leak around the intake gasket? took the carb off for a reclean will they act like this if i missed a small fragment or is there something i should be paying more attention too? the only other thing i can think of is a problem with the needle do they go bad somehow? TIA

 

[crxess]

Re: 15hp high idle

When you had the carb off, did you notice if the throttle butterfly goes fully closed? If anything is holding it a little open the idle will be up.

Yes, a worn or broken low speed adjuster can increase idle from to much air flow. However, if turned all the way in gently to stop, it should lower or stall.

 

[rodneym1965]

Re: 15hp high idle

it stalls at about 1 turn in. i noticed it isn't as sharp as other needles Ive seen in other small carb's. butterfly in carb seems to be closing but it isn't completely vertical

 

[crxess]

Re: 15hp high idle

Ok, at 1-1/4 turn is it running high or stumbling?

From 1-1/2 turns very gradually turn in. As the motor stumbles, stop and wait for it to clear up. Find the lowest smooth point. then back out 1/8 and see how the idle is.

Also make sure your needle isn't dragging on the lower housing or anything.
On my 6hp the needle barrel drags the upper edge of the opening and stops over 1 full turn from stop. I discovered this by accident and carefully worked past it. Can now idle under 300 rpm before shaking to much.

 

[rodneym1965]

Re: 15hp high idle

at 1 1/4 turn it would act like its running out of gas at about 11/2 turns it starts bogging like its running out of fuel

 

[crxess]

Re: 15hp high idle

Ok time for a few unconventional test.

Fill a spray bottle with water. Set the spray to stream. With the engine idling spray heavily around the carb to motor gasket(avoid the open throat) Also Spray around the Reed plate gasket.
If you have a gasket leak, the water will be sucked to the opening and momentarily bog the motor down.

If nothing is found there, while still idling, take a piece of cardboard and block 1/3 of the throttle opening.

What is the result?

 

[rodneym1965]

Re: 15hp high idle

thanks i'll try that tonight and let you know what i find out

 

[rodneym1965]

Re: 15hp high idle

well got the carb recleaned and back on last night and it seems to idle alot better must have missed something first time when i was cleaning it. the needle seems a little touchy though if you move it just a slight move makes a huge difference. trying to get this thing slow enough to troll. i bought it last year used and it would troll along at 1.5 all day as well as the first part of this year. now it will troll at 1.5 for about 5 min then dies out if i turn the needle out i touch it purrs along but between 2.4 and 2.8. guess i might have to just get a small drift sock or something. it couldnt just be plugs not letting it keep running at the lower speed could it? havent changed them since i got the motor just baffled why it doesnt run as slow.

 

[crxess]

Re: 15hp high idle

After all this work, I'd throw in a new set of plugs(properly gapped) and try tweaking it a bit more.
Sounds like your getting close.

 

[rodneym1965]

Re: 15hp high idle

hey just want to thank you for all your help!

 

[Rick.]

Re: 15hp high idle

Sounds like your happy and that is great, but I just have to say you should be able to troll all day at 1.4 with that motor. There has to be a reason it won't get down there. I don't see the idle adjustment knob on your motor that I referred to. but I'm confident it will have something just like it in a different place. Have you done the linc and sync? Rick.