Idle Air Control - 1985 Bronco II
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Cross-Country
Joined: Jun 2003
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From: Charlotte, NC
Idle Air Control - 1985 Bronco II
Carbureted 2.8L V6 does not want to idle. It will start right up but only stays running if continuously feathering the throttle at around 2,000 RPM.
Is there a way to test the idle air control valve (harness and solenoid itself) using a Power Probe, multimeter, etc.?
Is there a way to test the idle air control valve (harness and solenoid itself) using a Power Probe, multimeter, etc.?
So the engine will not run at all unless you keep your foot on the throttle? When was the last time the carburetor was rebuilt?
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Cross-Country
Joined: Jun 2003
Posts: 84
Likes: 4
From: Charlotte, NC
Yes, an IAC on a carburetor. Early to mid-80's was the transitional period when the throttle body fuel injection was being introduced and they also gave the carburetor one last gasp to try and meet emission requirements. GM was also smoking the same stuff and had a similar carburetor of their own.
I will probably perform a Duraspark conversion in the long run but was hoping to pin-point the current problem in the meantime.
A carb rebuild is where I started, and this was just done. Had the same symptoms before and after the rebuild.
I will probably perform a Duraspark conversion in the long run but was hoping to pin-point the current problem in the meantime.
A carb rebuild is where I started, and this was just done. Had the same symptoms before and after the rebuild.
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Cross-Country
Joined: Jun 2003
Posts: 84
Likes: 4
From: Charlotte, NC
Sorry for the delay. Vehicle is located out of state so access is sporadic.
I removed the IAC and cycled the key to the run position several times. The plunger moved in and out. I'm assuming the plunger is either fully open or fully closed and does not have a variable position based on engine conditions. Is this true?
I disconnected and plugged each of the many vacuum lines one-by-one at their source to see the effect. There was no effect at all. Each time the engine would start easily but would require pumping the throttle slightly at around 2,000 RPM to keep it running.
I hooked up a smoke machine and could see no smoke escaping except from the normal locations.
Removed the top of the carb and the float was properly set per specifications for wet height. The injector nozzles are squirting fuel into the venturi's when the throttle is pumped. I removed the idle screws and spayed carb cleaner into them. Cleaner squirted into the venturi's with no clogging.
Cap and rotor were replaced initially due to corrosion so they are good.
Any chance there is an electrical problem with the ignition module, etc.?
I removed the IAC and cycled the key to the run position several times. The plunger moved in and out. I'm assuming the plunger is either fully open or fully closed and does not have a variable position based on engine conditions. Is this true?
I disconnected and plugged each of the many vacuum lines one-by-one at their source to see the effect. There was no effect at all. Each time the engine would start easily but would require pumping the throttle slightly at around 2,000 RPM to keep it running.
I hooked up a smoke machine and could see no smoke escaping except from the normal locations.
Removed the top of the carb and the float was properly set per specifications for wet height. The injector nozzles are squirting fuel into the venturi's when the throttle is pumped. I removed the idle screws and spayed carb cleaner into them. Cleaner squirted into the venturi's with no clogging.
Cap and rotor were replaced initially due to corrosion so they are good.
Any chance there is an electrical problem with the ignition module, etc.?
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