car idleing high why

[86_olds]

why does my cutlass 86 stock 307 idle high out of no where it doesnt matter if its cold or normal running temp if i leave it idling at it idles normal for about a minute out of no where it will just idle like around 1500- 2000 rpm for no good reason i got the carburator rebuilt not that long ago maybe 3 months and havent driven it much could the reason be that it needs to be broken in or could it some kind of vacumm leak some where ? o and another thing when it idling high is i rev the engine alittle like lets say 3500rpm then let go it will idle normal again but the slowly start idling high any help?

 

[monte olrac]

Check your fast idle solenoid if you have one

 

[Bonnewagon]

Could be a vacuum leak, but there would be pinging with that. Check the choke, make sure the connection is good and not alowing the coil to cool off. Test with a light on the choke coil tab, not the wire. They rust, and the grey connector breaks easilly.

 

[mheath717]

Mine started doing that out of the blue about two weeks ago. I gave the fast idle screw 3/4 of a turn to the left and it cleared it right up.

 

[86_olds]

Mine started doing that out of the blue about two weeks ago. I gave the fast idle screw 3/4 of a turn to the left and it cleared it right up.

yeah if i go any lower it will just idle to low and turn off on me when in drive

 

[Peter]

Mine started doing that out of the blue about two weeks ago. I gave the fast idle screw 3/4 of a turn to the left and it cleared it right up.

yeah if i go any lower it will just idle to low and turn off on me when in drive

sounds like a vacumn leak or possibly an egr gasket or intake gasket perhaps.

 

[Bonnewagon]

Is the choke open or closed when hot?

 

[86_olds]

i dont know how to tell if chokes open am do what u guys told me to check with test light

 

[Bonnewagon]

With motor off, remove air cleaner, plug vacuum nipple. Start motor, check what rpm fast idle is, watch as choke butterfly slowly opens. When fully open, tapping throttle should drop fast idle down to curb idle. That is what SHOULD happen. The grey wire that goes to the round black housing on the side of the carb gets 12 volts when the ignition is ON. It heats up a coil inside and that opens the choke butterfly. If it is not getting 12 volts, or intermittently, choke stays closed, and idle stays too fast.

 

[mheath717]

Mine started doing that out of the blue about two weeks ago. I gave the fast idle screw 3/4 of a turn to the left and it cleared it right up.

yeah if i go any lower it will just idle to low and turn off on me when in drive

I wasnt talking about the idle screw... I was talking about the fast idle screw under the choke on the other side of the carb. Control the idle when you first start it up, and its stone cold.