bad idle after warm up early 80s Merc 90 Tower Power

stevehendo34

Petty Officer 3rd Class
Joined
Aug 7, 2010
Messages
92
Won't idle after warm up--dies.
I have to keep it running by pulling up fast idle lever.
Starts fine
Idles fine when cold.
Has 2 carbs
Any ideas?

Shop tuned it up said they fixed it but it did not help.
They wanted more $$ to work on it.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: bad idle after warm up early 80s Merc 90 Tower Power

Get a refund and then check the spark to see if some spark fails when warm. i use a timing light to do this quickly, putting the lead on each wire in turn however you could ground a spark before the engine cooled
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,033
Re: bad idle after warm up early 80s Merc 90 Tower Power

Gee, an early 80s 90HP motor would be a IL6, with three carbs. You have a serial number?

So it starts cold fine, and then warms up and won't run? Carbs could be out of adjustment.
 
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