| Author |
Message |
    
Michael Crouse
New member
Username: chiefmc
Post Number: 1
Registered: 10-2009
| | Posted on Wednesday, October 28, 2009 - 10:12 pm: | 
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My 1988 Mariner 115 6 cylinder will start and idle all day. It will run up to 1500 rpm no problem, but as soon as you try to throttle up above 1500 it will die. Occasionally you can sneak it past that point and it then runs great up to 5400 rpm. If you throttle back but stay above 1500 you can drop the throttle and it responds every time. It has acted this way since I bought the boat/motor. I've only had it out a few times, last time after rebuilding the carbs (which were perfectly clean and measured good for float height and needle drop, but I put all new in). Any ideas? |
ian summerfield
Member
Username: budgie14
Post Number: 65
Registered: 06-2009
| | Posted on Thursday, October 29, 2009 - 01:32 am: |
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Hi Michael,does it make any difference if you squeeze the fuel bulb?idle mixtures lean? compressions ok? . |
Fastjeff
Senior Member
Username: fastjeff
Post Number: 7038
Registered: 09-2003
| | Posted on Thursday, October 29, 2009 - 06:59 am: |
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Your carbs' idle mixture might be set a bit too lean. Try opening each idle adjustment screw 1/4 of a turn and see if that helps.
Jeff |
Michael Crouse
New member
Username: chiefmc
Post Number: 2
Registered: 10-2009
| | Posted on Thursday, October 29, 2009 - 09:19 am: |
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I'll try making it rich by a 1/4 turn and hope I can get back to the lake soon. I take it from your suggestions that it is still running off the idle jets until about 1500. I haven't done comp checks yet but hope to this weekend. I initially assumed crud in the carbs, then the spark advance control box (which I read some folks think should be discarded... Do you agree?). Thanks for your help. |
Fastjeff
Senior Member
Username: fastjeff
Post Number: 7040
Registered: 09-2003
| | Posted on Thursday, October 29, 2009 - 10:23 am: |
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Try the carbs first. The transition from idle speed to 1,500 is about the time they start to open.
Be sure to let me know how you make out!
Jeff |
'Bandit
Advanced Member
Username: timebandit
Post Number: 792
Registered: 09-2007
| | Posted on Sunday, November 01, 2009 - 10:45 am: |
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The primary pickup timing is MUCHO important-O.
Get the manual and do the link and sync.
The box you refer to is the idle stablizer. That can be safely removed. You only need it when you have a big wheel prop. (20+") |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1639
Registered: 05-2001
| | Posted on Sunday, November 01, 2009 - 10:54 am: |
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Another possibility is that the high speed winding on the stator has gone bad. You can check the voltage at the switchboxes. The red or red/white stripe is the high speed winding. The blue or blue/white stripe is the low speed. |
daniel sullivan
Member
Username: sullybe
Post Number: 70
Registered: 07-2008
| | Posted on Saturday, November 07, 2009 - 07:07 pm: |
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I have an 86 Merc 115 that was having close to the same problem. I found the new gas we have was eating the seal in the two piece carb floats and it was filling the floats with gas. Easy fix get solid floats. |
jamie campbell
Advanced Member
Username: outboard_doctor
Post Number: 722
Registered: 02-2009
| | Posted on Sunday, November 08, 2009 - 02:29 am: |
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Go with Jeffs suggestion as i would suspect the carbies are set a little lean |
