1998 115 hp mariner rough idle

angles4lyfe

Cadet
Joined
Sep 6, 2005
Messages
15
Hi i have a 98 inline 4 cyl 115hp mariner, it has a very rough idle and almost always turns off when put in gear. it runs perfect at WOT but struggles to stay on on idle or in idle gear. i went ahead put in new plugs rebuild the carburaters, rebuild the fuel pump put in a new primer bulb, and checked compression which is good. What do you think my problem could be?
 

jaybirdtx

Petty Officer 3rd Class
Joined
Sep 19, 2005
Messages
79
Re: 1998 115 hp mariner rough idle

Did you check your ignition system @ idle?
 

angles4lyfe

Cadet
Joined
Sep 6, 2005
Messages
15
Re: 1998 115 hp mariner rough idle

well i know i have spark on all the cylinder i checked that with a spark tester.
 

andy6374

Lieutenant Commander
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Aug 4, 2005
Messages
1,617
Re: 1998 115 hp mariner rough idle

When you rebuilt the carbs, did you check that the throttle shutters in carb throats are fully closed at idle. This will surely give you a rough idle if there are open even a bit.<br /><br />What RPM's are you running at idle.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: 1998 115 hp mariner rough idle

Did you get the carbs back in the same position they were removed from? If not, the linkages between each carb can be off marginally, creating the butterfly fully closed problem Andy mentioned. It would appear you need to do a sync operation to get the linkage set correctly.
 

angles4lyfe

Cadet
Joined
Sep 6, 2005
Messages
15
Re: 1998 115 hp mariner rough idle

i did the sync on the carbs perfect, all the throttle shutters are completely closed and yes they are put in the same position i numbered them before even taking them apart. i was thinking it could be the stator or the trigger. what do u guys think?
 

DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: 1998 115 hp mariner rough idle

Recheck the spark.A good ignition system will let the spark jump 7/16 of an inch.My guess is at least one cylinder will fail this test.Could be trigger or stator,but usually the switch box.<br /><br />DHP
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: 1998 115 hp mariner rough idle

Check the spark as DHP indicated. Loosing a cylinder on those inline 4's is a rough going.
 
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