1996 johnson 90 hp idles to fast

[shadetree2]

my engine idles to fast . adjustment is backed off all the way. it has new intake manifold an carburetor gaskets an no vacuum leaks. could low engine compression be the problem. compression 86?-95?-105?-107?. ps 2 stroke.

 

[racerone]

????--Doubt that low compression is the problem.-------Are all 4 throtlle plates closed at idle ?-----Is the cable adjusted to pull arm against the stop screw ?

 

[shadetree2]

it has #2-2barrell carbs plates are closed at idle. stop screw backed off all the way.

 

[racerone]

Yes I know what is on your motor.-------But is the throttle cable pulling things back against the stop ?----Is the timer base sticky ??---Are you allowing for " quickstart " to function if so equipped ?

 

[boobie]

Got a model # ????

 

[shadetree2]

Yes I know what is on your motor.-------But is the throttle cable pulling things back against the stop ?----Is the timer base sticky ??---Are you allowing for " quickstart " to function if so equipped ?

plats are closed all the way against the stop / timing base is not sticking / no quick start.

 

[shadetree2]

Got a model # ????

1996 Johnson 90 hp model / no j90tleda.

 

[emdsapmgr]

The idle is set on that model by adjusting the idle timing. Sounds like the timer base is set incorrectly. Probably need to adjust the idle timing by adjusting the threaded idle timing rod, part # 334739. When installing new parts from another engine, it's common that some re-adjustments will need to be made. Have you though about the implications of the compression differences? When the compression numbers are that far off, it's a sign of other internal problems.

 

[shadetree2]

adjusting timing rod either way hardly makes any difference on idling.

 

[emdsapmgr]

All 4 barrels must idle with the throttle plates completely closed. You may have to pull the airbox cover off to validate this. If one carb's butterlys are slightly ajar, that will affect the idle.

 

[boobie]

Agree with EMDS on the compression.. OMC says no more than 15 psi per cylinder..

 

[emdsapmgr]

When you install a new intake manifold, it may be machined slightly different than the original. You may need to do a complete sync and link to re-establish the correct carb/ignition timing relationships.

 

[shadetree2]

could the timing base be bad.