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Idle trouble


Sean092

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I'm new to this forum I've been reading around to see if anyone happened to have the same issue I'm having but haven't had much luck I recently bought a 85 720 2wd and it ran ok but started having problems idling it funds fine when cold but after it warms up it will die unless I keep my foot on the gas I turned up the idle speed to keep it running but now it idles pretty high then drops down when warmed up it runs but not well I've replaced my fuel filters made sure the choke is working right and checked to make sure the fule cut off solenoid has power but its wired funny and I'm not sure exactly where it is so posed to be wired to does anyone have any ideas on what to could be going on?

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Do you have an O2 sensor in the exhaust manifold?

 

 

Turn ignition on  off  on and off (don't start). Listen near the carb you should hear a soft click from the idle cut solenoid. This would shoe that it's getting power ... at least.

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If you have a non operating O2 sensor then the mixture cannot be regulated with feedback from it when the engine is warmed up.

 

When the engine is cold it runs in open loop mode. This is a pre set mixture for warm up. When warmed up the Osensor detects the oxygen content in the exhaust and the ECU adjusts the carb to tightly control the mixture. This is called closed loop operation.

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The connector is thought to be problematic with the wires breaking internally and loosing connection. Sometime wiggling the connector makes the connection and it improves the idle. Narrows the problem down.

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