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  #1  
Old 07-26-2004, 08:57 AM
Dan K Dan K is offline
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Fast Idle after warm-up

Can anyone offer some insight into this problem for me?
1981 S&S 351 Powerslot electronic ignition.
I had my carb rebuilt (4160) as preventative maintenance since it has been awhile. After reinstalling the idle has been giving me problems.
It will idle low when cold and will stall when put into gear unless I give a little throtle imediately. Then after it warms up the idle is around 1100 rpm or so which is pretty high since the boat moves pretty fast at this rpm. When I try to lower it down by adjusting the idle screw it will die out. I changed my timing got 10 BTC it was at 14 but my valve cover indicates 10. I also tried to adjust the idle air mixture screws but this didn't produce any better results when I lowered the idle.
I have to say that the boat ran better before the rebuild but sucked a larger amount of fuel than it usually did. The fuel consumption is better now, but the idle isn't what I believe it should be.
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Old 07-26-2004, 10:48 AM
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lakes Rick lakes Rick is offline
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I would check my choke for proper adjustment and look for a vacuum leak...
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Old 07-26-2004, 12:46 PM
Dan K Dan K is offline
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Thanks Rick,
The only possible vacuum leak I could find is on the port that is near the electric choke coil. There is a suction on this port, but I don't know what it is for. Do you have any ideas. I wish I had a picture of it handy it would make it easier to explain.
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Old 07-26-2004, 01:48 PM
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lakes Rick lakes Rick is offline
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Hopefully Jimn will sign on here..

two things...

1. Is your choke a hot air or electric??? If its hot air I would say your are missing the tube from the intake to the choke...

2. If your choke is electric you need to plug the unused vacuum port at the choke.... If its what I think a brass cap or possibly a rubber vacuum plug would take care of it....

3. Spray some carb cleaner at the port.. IF your idle changes thats the problem.... From what you have said, sounds like a vacuum leak....
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Old 07-26-2004, 02:18 PM
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JimN JimN is offline
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Check the throttle plate to see how far open it is at idle. It should be almost closed. Remove the throttle cable when you check the idle. I have seen these stick and stretch, giving more or less throttle than it should. Talk to the place that rebuilt it and they should be able to help you out here.
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Old 07-26-2004, 02:35 PM
Dan K Dan K is offline
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Rick,
I have an electric choke, I have covered the port with my finger to see if anything changes and could not notice a difference. I will trying spraying some carb cleaner to see if there is a difference.

Jim, The entire rebuild experience was a nightmare. I took it to a performance parts place that sent it to their rebuilder and was promised delivery in 5 days. 9 days later when I needed the carb for a two week vacation they told me they still needed some parts. But the performance place did not know which parts the rebuilder needed. In 1/2 hour I located two different locations that had complete marine rebuild kits for this particular model, I notified them of this and they said that the rebuilder found the parts he need and would have it completed at the end of the day. I got this carb in the nick of time since the boat is kept at our cottage and we were on our way. This is why I usually do these things myself.
So I don't know how much help these guys are going to be, I believe they did a proper job, the only things that I may suspect are not optimal would be the powervalve and jetting, but these do not come into play with my idle problem as far as I know.
Do you have anyother thoughts ? The idle is high even when the cable is disconnected, since I always disconnect it to adjust the carb.
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Old 07-26-2004, 10:37 PM
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JimN JimN is offline
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They need to get it back and adjust it right. 1100 is way too high and is hard on things when it slams into gear. It should be closer to the right setup than it was when you got it back and they should guarantee their work and the work by their carb rebuilder.
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Old 07-27-2004, 11:02 AM
Dan K Dan K is offline
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I agree with you Jim. They should, but I do not have a lot of recourse with this and they are 2 1/2 Hours away. My best bet is to adjust it properly myself.
Do you have a suggestion on what order to tackle things ?
looking for and fixing vacuum leak
Setting timing
Lowering idle
adjusting Idle air mixture
any other items you may suggest.
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Old 07-27-2004, 02:13 PM
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JimN JimN is offline
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Why don't you have much recourse? They had it done for them, so they need to cover it not working properly. I know it's a haul to get there, but if they sent it to someone to have it done, it's as if they did the rebuild.
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Old 07-28-2004, 11:34 AM
Dan K Dan K is offline
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Jim,
I certainly can take the carb back to them and ask them to get it adjusted properly, but then I will be faced with the downtime during my peak usage. I am just trying to get this to a livable situation until September when I won't mind the downtime as much, or ideally get it adjusted properly myself with no downtime and no need to get the performance shop involved.
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