85 Mercury 50 hp won't idle in gear.

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
I took it out on the lake and after it warmed up we idled out of the no wake area and everything was fine. Then all of a sudden after the first time I accelerated the idle speed jumped up but then it would stall out when trying to idle in gear. . The compression checked good on all four cylinders and now I am trying to check the spark. I bought a spark tester that inserts into the plug wire and the other end grounds but so far I haven't been able to see any spark. My remote start button quit on me so I checked the compression with the key switch and the kill switch pulled. I had the remote start leads hooked up to the solenoid, the red to the red and the other to the other contact. Is that right? I hate to play with the idle adjustments yet because it took so long to get it right the first time. It looks to me like something stuck when I accelerated but then maybe it won't idle in gear because one or more cylinders isn't firing properly. Does this sound right?
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: 85 Mercury 50 hp won't idle in gear.

I managed to use a piece of #12 solid copper wire in place of the remote starter and found out I'm not getting spark at the #2 plug wire. Fixing that should help take care of the problem with it the stalling in gear. After that I will work on the idle speed problem. Now the question is which is it the coil or the switch box? Is there anything else it could be?
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: 85 Mercury 50 hp won't idle in gear.

I switched coils and got spark on #2 so it looks like it will be a cheap fix. I am constantly amazed at how well this old motor has performed with all of the issues it has had and all of the things that I have fixed on it already, everything from rebuilding the carbs because of flooding to replacing the stator and trigger because the wires were corroded and bare. Still hoping to get it purring along soon.
 

gpfishingdude

Chief Petty Officer
Joined
May 1, 2012
Messages
538
Re: 85 Mercury 50 hp won't idle in gear.

After getting the new coil installed and firing on all four cylinders I realized that the carbs. needed readjusting. I started with the basic 1 1/2 turn out and tuned the top one first. Then adjusted the bottom one. The idle picked up so much that I had to adjust it down again. Should be back on the water in a couple of days to see if it will keep idling this time.
 
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