# please help with idle issue



## grover (May 31, 2012)

It is a 1989 Evinrude 8hp. It will not idle without pulling out on the choke just slightly. If you push the choke in it just runs out of gas and dies. I found a crack in the fuel pump and replaced that. Still would not idle. sprayed a little carb cleaner around the side of the carb and it picks up like it should so I think the gaskets on the carb are leaking so I put a new carb kit in. Still will not idle without the choke and spraying the side of the carb helps it idle. Put new fuel lines on. Still no help. Can't figure out where it's leaking. 
When we put the carb kit in I had two pieces left. A very small rubber tube about 1 1/2 to 2 inches long and a small dish shaped piece about 1/2 inch in diam. The only place I see that could go would be on the side of the carb where there is a mesh screen.
Any ideas?


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## Pappy (May 31, 2012)

The carb kit you used may fit other carbs than your model. The tube is used in a few engines up to around 15hp in your year vintage. You should have an idle mixture adjustment and am wondering if you have tried to richen it using this as it was not mentioned in your post.


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## grover (May 31, 2012)

The only adjustment screw I see on my carb and in the schematic is called the slow speed needle. I started with it all the way in and then backed it out 1 1/2 turns. Do you richen the mixture by screwing in or out? I've tried it in several positions and it doesn't help. The only thing that helps is pulling the choke out a little. Or spraying some carb cleaner on the side of the carb. When this happens I thought it meant you had an air leak somewhere.
Thanks


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## nomowork (May 31, 2012)

If it runs better with choke pulled out, it may be getting too much air, such as a vacuum leak somewhere. Try starting motor and spraying carb cleaner around suspected areas to see if it changes the idle or running. WD40 or similar can be used also and sometimes if you find that leak, it'll kill the motor instantly.

Good luck.


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## shawnfish (Jun 1, 2012)

grover said:


> The only adjustment screw I see on my carb and in the schematic is called the slow speed needle. I started with it all the way in and then backed it out 1 1/2 turns. Do you richen the mixture by screwing in or out? I've tried it in several positions and it doesn't help. The only thing that helps is pulling the choke out a little. Or spraying some carb cleaner on the side of the carb. When this happens I thought it meant you had an air leak somewhere.
> Thanks



when you adjust your slow speed needle. back it out 1 1/4 turns, going out richens it i beleive. either way, make very small adjustments(bareley turn it either way) and wait for 15-30 seconds for the fuel and carb to catch up to the adjustment before making another. check your linkage from your choke knob to carb also to make sure when its all the way in it is 100% closed on the carb. do you have fresh gas? give that a try and see what happens...oh is the motor used or have you had it since it was new?


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## shawnfish (Jun 1, 2012)

did you check your fuel filter? (screen on your fuel pump)?


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## wasilvers (Jun 1, 2012)

If you have an external tank maybe the bulb needs to be replaced - not letting fuel through?

I would richen the mixture to 1 1/2, find the idle screw and turn it up so it idles at 1000 rpm, and go fishing.


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## Pappy (Jun 1, 2012)

Your "initial" setting is 1 1/2 turns. This is just a general starting point. Since your engine is lean go ahead and turn the adjustment screw out or counter clockwise until the engine smooths out and runs on it's own. This should be done with the boat in the water, not on a hose for final adjustment but you can get it in the ballpark on the hose. You may want to start at 2 1/2 turns just so you dont have to fool around with choke to keep it running. If you start at 2 1/2 turns then let the engine warm up and go back in or lean by 1/8 turn increments until you reach the highest rpm or the engine "sneezes" lean and then back it back out 1/8 to 1/4 turn. Either way this should take care of your issue. Once you get the engine running smoothly you may want to check the relationship between the throttle blade opening and the spark advance.


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## grover (Jun 1, 2012)

How about the issue of the idle leveling out when I spray around the carb? Wouldn't this mean it is sucking air somewhere. I think so, I just can't find where it is sucking air.


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## nomowork (Jun 1, 2012)

grover said:


> How about the issue of the idle leveling out when I spray around the carb? Wouldn't this mean it is sucking air somewhere. I think so, I just can't find where it is sucking air.



I had an issue with a four barrel carb before that was sucking air through the butterfly shaft. There are repair kits for the shaft bushing, but the cost was too much IMO so I just bought a new carb.

Good luck finding that pesky gremlin.


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## Pappy (Jun 1, 2012)

The engine will pull air around the openings for the throttle shaft. When you spray around this area the engine will change...they all will. You can start almost any carbureted two stroke and see the same thing you "found" with yours. Try the mixture screw first.


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## grover (Jun 8, 2012)

Still not having any luck. We can get it to run some by really throttling up and back quickly but can't keep an even rpm without it slowing down and dying. The best thing to do to keep it going is pull out the choke a little. It has a new fuel pump and new carb kit. I can't tell if the idle mixture screw has any effect at all in how it runs.
I can't see how this would be fuel filter, bad gas, bad primer bulb because it will rev up and run pretty good untill you try to keep an even rpm or let it rev down to idle. I think it would run all day if we kept the choke out just a little.
Not sure what the throttle blade is. 
Not sure what the throttle blade is. I'm trying to get enough posts to get a pdf manual. Maybe I'll find out then.

I think it has to be some issue in the carb but I'm far from an expert.


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## grover (Jun 8, 2012)

I think it is fixed. I took the carb apart again. Didn't find anything wrong really. Just cleaned...again...and put back together. I backed out the slow speed idle screw about 1 and 1/2 turns, tried to get it to idle, no go. Kept backing it out 1/2 turn at a time and I think it was 3 of 3 1/2 turns out it started to idle without the choke. Fine tuned a little bit from there but so far it seems fixed. I think the main issue when we bought it is it didn't have the flex tube installed in the carb. Found that out when it wouldn't idle and we put a new carb kit in. Since it didn't have the flex tube in it when I took it apart then I didn't put it back in. Yeah, laugh at me...it was my first carb rebuild and I wasn't sure at the time where it went and even if it was used in my application.

Positive side of things is I'm getting good at taking off the carb and putting it back on!


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## Gramps50 (Jun 8, 2012)

I had an idle issue on my 20 HP Merc and it turned out to be the quick disconnect on the motor. The clue to the problem was the primer bulb would not get hard and stay that way. Yet the fitting really didn't show any signs of leaking, at least not fuel, but it was sucking air.


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