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1996 Mariner 90 HP Rough Idle

G

gwfiii

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"I've got a 1996 Mariner 9

"I've got a 1996 Mariner 90 hp 3 cyl. It idles rough, surges at idle, bogs upon acceleration, and after running wide open and returning to idle will stumble and often die. I've cleaned with Power Tune. Idle timing is set at 3 degrees BTDC, air screws are set at 1 1/4 turns out, compression is apprx 110/cyl. Still has problem. Any suggestions?
Thank you.
Webb"
 
"My son has a 60hp and was doi

"My son has a 60hp and was doing the same thing. It was the advanced timing. You have to adjust while you are ramping engine up on water, so go out on a calm day.
After I adjusted it, and almost fell off twice, it works alot better now.
Try that."
 
Thanks guys. I will try your s

Thanks guys. I will try your suggestions. Is it possible to get one of these engines to idle smoothly or are they rough by design?
Thanks.
 
"it should idle smooth, if the

"it should idle smooth, if the gas went bad in the carbs over the winter the jets might be clogged. No gas means no oil, best to remove and clean carbs."
 
"No, Powertune is sprayed dire

"No, Powertune is sprayed directly into the carb throat. It gets the cooties out of the intake, the ports, the cylinder and even helps clean up the rings, but does not flow through the fuel system.

The only sure way to get varnish out of a carb is remove it, disassemble and clean while disassembled.

Other products claiming to do that with it in place can be put in the "wishful thinking" catagory.

Products as such are great for "preventative" measures, but after the fact are very limited in their effectiveness."
 
"Hi Graham, I removed the air

"Hi Graham, I removed the air screw and sprayed power tune in the hole. Will the power tune get down into the bowl and jets this way?
Thanks,
Webb"
 
"That will get it in there, bu

"That will get it in there, but don't make the mistake of thinking that it will work as well as a "carb cleaner".

It certainly won't hurt, but it's primary purpose is to remove carbon. If you have clogs developing or varnish build-up you really need to have the product stay on the part to clean it - powertune will quickly move through the system and is significantly weaker than a real carb cleaner.

My primary use for powertune is when bringing motors out of storage - cleans out the carbon and fogging oil and other cooties really well. I use it to try prevent issues, not really fix them once they have set in.

Additionally a gas additive (2 stroke safe) for cleaning carbs or injectors may also be a preventative, but again, after the problem is there, you can't really get a solution out of a can that is going to replace a tear down..."
 
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