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Old 08-15-2017, 11:49 AM   #1
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Default Engine won't idle

You guys are the best. So far you've helped me replace the impellers of two completely different water pumps, replace exhaust pipes, replace rotor, distributor cap and spark plugs, replace serpentine belt. Both engines running, moving water, and staying cool. However, (there is always a however), the port engine will only run at 1000 rpms or more. Soon as I back down the throttle it stalls. It also back fires sometimes when starting. Oh, it's a mercruiser 4.3 with bravo 2 sterns.
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Old 08-15-2017, 01:31 PM   #2
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Is the a carbureted model? If so, when was the last time the carb was rebuilt?
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Old 08-15-2017, 03:00 PM   #3
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More info needed on the engine...
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Old 08-15-2017, 04:08 PM   #4
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Quote:
Originally Posted by bobgaudette View Post
You guys are the best. So far you've helped me replace the impellers of two completely different water pumps, replace exhaust pipes, replace rotor, distributor cap and spark plugs, replace serpentine belt. Both engines running, moving water, and staying cool. However, (there is always a however), the port engine will only run at 1000 rpms or more. Soon as I back down the throttle it stalls. It also back fires sometimes when starting. Oh, it's a mercruiser 4.3 with bravo 2 sterns.
Well after all that you owe us a beer.

What year are the engines? ThunderBolt IV or V ignition? Have you checked the timing as to advanced can cause the backfire and may not let her idle. A vacuum leak or worn carb can cause the same but if EFI the IAC is a common issue.
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Old 08-15-2017, 08:07 PM   #5
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The engine is 2007. Not sure about the rest of the stuff. I was wondering if it could be the idler air control. I ran some carb cleaner stuff through it and it almost runs at an idle now. I'm sure a carb rebuild would help, but is that something I can do, or leave that for a mechanic?

Is the iac something that can be cleaned or does it just get replaced? I'm sure I see it attached to side of carb with a plug attached.

And yes Mike, I owe you guys a six pack.
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Old 08-15-2017, 09:46 PM   #6
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Please post a picture of you engine close up. You just mixed a card engine and a EFI in you last post. However it sounds like it has a carb so no IAC.
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Old 08-16-2017, 03:21 PM   #7
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The engine is 2007. Not sure about the rest of the stuff. I was wondering if it could be the idler air control. I ran some carb cleaner stuff through it and it almost runs at an idle now. I'm sure a carb rebuild would help, but is that something I can do, or leave that for a mechanic?

Is the iac something that can be cleaned or does it just get replaced? I'm sure I see it attached to side of carb with a plug attached.

And yes Mike, I owe you guys a six pack.
No offense intended but given your mechanical knowledge I'd take it to a mechanic.
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Old 08-17-2017, 01:17 PM   #8
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I would suggest having a mechanic rebuild it. They'll re-install and get it 'tuned' up and running right when the process is done.

I would also suggest starting with a small single-cylinder carb from a small engine like a small outboard. I learned on dirtbikes, for example.
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