Rough idle and dies when put in gear

J

Jamz33

Petty Officer 3rd Class
Joined
Jun 14, 2018
Messages
89
I have a 1998 mercruiser 305 and the engine was removed to repair some power steering issues and now occasionally it idles rough and dies when going into gear. Any ideas at what I should be looking for? Thank you.
 
ESGWheel

ESGWheel

Chief Petty Officer
Joined
Aug 29, 2015
Messages
588
From the limited info it sounds like you are occasionally running on less than 8 cylinders which could easily be ign. related (example: spark wire shorting out). So need more info like:
  • Conditions under which is runs rough like cold or warmed up
  • What RPM are you seeing when idling rough
  • What RPM are you seeing when idling smooth
  • Under load does it run just fine or does it seem underpowered sometimes
  • Last time a full tune up that included all things ign wise (points, capacitor, plugs, cap, rotor, wires)
 
J

Jamz33

Petty Officer 3rd Class
Joined
Jun 14, 2018
Messages
89
It idles bad both warm and cold intermittently. Always runs strong otherwise down the lake. Problem always is idle and trying to get it in gear and then it dies. Doesn’t do it all the time though.
 
J

Jamz33

Petty Officer 3rd Class
Joined
Jun 14, 2018
Messages
89
Im and hour from the boat so it will be a bit before I can get the RPM. It’s been atleast a couple years with the tune up. It is carbureted. It may be just a coincidence that it started acting up after they reinstalled the motor but I believe the 2 are related I’m just not sure where to start.
 
ESGWheel

ESGWheel

Chief Petty Officer
Joined
Aug 29, 2015
Messages
588
Agree tough to believe in coincidences. One possibility is the dist cap got smacked and has a crack causing it to intermittently short out so not running on all 8, or an ign wire got damaged. When at the boat and idling, run your hand around the dist and along the plug wires. Get a tingle or shock > there is the issue. If none, suggest replacing all anyway incl. plugs. And take note of condition of plugs and which hole. Post pics.
 
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