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Why doesn’t my 89 15HP have and idle adjust screw?

J

JerEazy

Contributing Member
1989 E15RCEC

going through diagrams I should have a small screw to turn up the idle “cam” (think that’s the term). But there’s no screw on the arm near the roller? Engine starts great with a little throttle turn on the tiller handle. But is very low when I put the throttle back to idle.

yes, I have adjusted the “idle adjust” knob. Has minimal impact on the idle. Its that the throttle needs a bit more at idle.

will take pictures at first light.
 
Those plastic arms break off which holds the screw. Is yours broken off? Sometimes folks like to overtighten the screw and the arm breaks off. I have other tricks to get more throttle for cold starting. We have several of these motors at camps in remote NW Ontario. They have all been "adjusted". This helps them start on 1st or 2nd pull when cold. It's the TIMING advance that's limited when in neutral, that's causing the problem with these.
 
timguy said:
Those plastic arms break off which holds the screw. Is yours broken off? Sometimes folks like to overtighten the screw and the arm breaks off. I have other tricks to get more throttle for cold starting. We have several of these motors at camps in remote NW Ontario. They have all been "adjusted". This helps them start on 1st or 2nd pull when cold. It's the TIMING advance that's limited when in neutral, that's causing the problem with these.
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so if I understand you correctly, you’re saying extend the timing arm a little bit to get it to idle higher at dead idle?

or what are you referencing?
 
And no - it doesn’t look broken off - it’s like I just have part #11 and no #12 maybe? Tough to tell in the diagram.
 
Is there a hole in your existing arm for a screw?
To answer your question, no I don't extend the timing arm. I notch the plastic stopper cam on the black plastic shifter/interlock.....to allow a little bit more timing advance IN NEUTRAL.
SURE YOUR NOT SUPPOSED TO MODIFY ANYTHING BECAUSE OMC IS "PERFECT".....right?
Well.....most of the time.
 
No there is not. I’m trying to get a picture of it uploaded, but not bing much luck

also, number stamped on carb is 390049
 
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---If that is a picture of your motor then see post #4----1989 models had a plastic top on the carburetor.
 
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racerone said:
---If that is a picture of your motor then see post #4----1989 models had a plastic top on the carburetor.
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so now we’re getting somewhere! Will be curious if the throttle cam follower part will interchange. The 390049 does read as a 15hp carb. Google looks like it’s from the late 70’s?
 
Racerone is exactly right. You have an all metal carby. In late 1987 they went to a plastic top and plastic float bowl carby. Yours has been changed if it is a 1989 model 15hp. There in lies your problem and the way it engages the plastic throttle control cam under the flywheel.
 
Snapper Fisho said:
Racerone is exactly right. You have an all metal carby. In late 1987 they went to a plastic top and plastic float bowl carby. Yours has been changed if it is a 1989 model 15hp. There in lies your problem and the way it engages the plastic throttle control cam under the flywheel.
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so I would guess on the earlier models there was another way to adjust the idle throttle setting
 
Pulled up diagrams, and it looks like 323327 is the cam follower with adjusting screw for earlier models (checked 83, 79 and others)

so I’m wondering if it’s like you said, it’s just broken?

I have a new 323327 arriving tomorrow. Going to be very curious if it fits.
 
racerone said:
At idle the throttle plate should be closed.----Idle speed is controlled with timing changes !
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ok - so advance the timing a bit at idle to keep it going? Adjust the rod? Or what would you recommend?

(shipping on a service manual is 2 weeks out)
 
If the carb has been changed, who knows what else was changed. The plastic top on the newer carbs often cracks right through the low speed needle bore. I grind a little bit then epoxy them with JB Weld or Marine Tex. Perhaps that's what happened on your original carb....so it got replaced with an older, tougher aluminum/steel design. My guess is that your tiller handle idle adjustment is not doing its job. These should be completely dismantled, cleaned and greased at least once in every ten years....especially if parked outside alot. There are adjustments to these cable type throttles that are explained in a good service manual. Without a manual, they can be confusing. How much play is there when you twist the throttle, until the cable moves?
 
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timguy said:
If the carb has been changed, who knows what else was changed. The plastic top on the newer carbs often cracks right through the low speed needle bore. I grind a little bit then epoxy them with JB Weld or Marine Tex. Perhaps that's what happened on your original carb....so it got replaced with an older, tougher aluminum/steel design. My guess is that your tiller handle idle adjustment is not doing its job. These should be completely dismantled, cleaned and greased at least once in every ten years....especially if parked outside alot. There are adjustments to these cable type throttles that are explained in a good service manual. Without a manual, they can be confusing. How much play is there when you twist the throttle, until the cable moves?
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ggoottcha. Ok. I checked the tiller for adjustments and didn’t see anything. But for sure. If one part is swapped, others may have.

I’ll just have to keep the throttle a bit twisted and ride it out for a bit.

thank you everyone for the help.
 
Quick update. Shown here the white one is what I have. The black is the part number from the diagram. My throttle is a bit “sloppy” and engages after the mark on the timing plate (cam plate?). Not being adjustable means nothing I can do about it. Sadly the rollers are not interchangeable between mine and the new one. So that is now on order as well, should be next week. 76251524-417B-4123-84CB-7D987F1E0B22.jpeg
 
JerEazy said:
Yes, thank you. Probably should say that after everyone’s responses and research I now know this is not an idle adjust screw. It is more of a timing pickup sync adjustment (may have the term wrong).
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That looks Ike a 70s carb set up. The motor that came off of would have had a side knob for the idle adjustment. Look under the flywheel and see if there is a screw under there for idle adjustment.
 
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