EVAP clicking?

[Nadine UK GTS]

My EVAP purge solenoid is 'clicking'? Can the solenoid stick on them (my '97 has been laid up for some time)? It looks like a sealed unit, serviceable? All the lines to it and canister and intake manifold are OK. It's set a trouble code, and my "service engine" light is on (I guess due to this). Anything I can do, or do I need to buy a new solenoid?

 

[Jerry Dobson]

If I had to guess, I would say that it could stick, just like a float in a carb when the gas **** up.

It is supposed to click as it works, but since you have a Service Engine light...Hmm.

Do you have access to a DRB3? There are some utilities in the tool to cycle the Evap Solenoid. Without this it is going to be tough to verify without just replacing it.

 

[Viper Wizard]

Hi Nadine,
Here's a little Info out of my Diagnostic book. You may need access to a DRBIII to pin point the problem.

Name of code: Evap Purge Solenoid Circuit

When monitored: With the ignition key on and engine running.

Set condition: After the arming conditions are satisfied: not powering down, not already in limp-in, time since the last solenoid activation > 72 micro seconds. The powertrain control module will set a trouble code if the actual state of the solenoid does not match the intened state.

Theory of operation: Its purpose is to regulate, by means of a duty cycle, the flow of vapors from the evap canister to the throttle body. The PCM controls the time the solenoid is on during a duty cycle. During off idle operations [higher flows], higher percentages of duty cycle are used. At idle [lower flow], lower percentages of duty cycle are used.

Possible Causes:
> Open or shorted control circuit
> Open fused ignition switch output circuit
> Open or shorted soienoid control coil
> Powertrain control module failure
> Connector terminals
> Connector wires

The most common problem with "Trouble Codes", I have found is the connecters or maybe in your case crushed wires?

Evap Solenoid Control > PK/BK and to cavity C20 on the Gray Connector at PCM.
Fused Ignition Switch Output > DB/GY and to the Ignition Switch.

If all looks good and without a DRB, I would try a Battery disconnect and let the PCM start over/relearn.

Let us all know how you make out.

 

[Steve-Indy]

Nadine, have you cycled your key to count the blinks on the engine light to establish a MIL code? Since most of us do not have a DRB handy, you may confirm your suspicions if you see MIL cobe 31...and/or you may find a second condition as well. Your Viper's plug should fit the generic (read that "el cheapo")scan tool...you know, the $100.00 type from the chain type auto store. On this tool you MAY find a generic code of P0443 representing "EVAP pump solenoid circuit"... "an open or shorted condition detected in the duty cycle purge solenoid circuit".

Or a P0441... "EVAP purge flow monitor failure"..."Insufficient or excessive vapor flow detected during evaporative emission system operation".

On later models, a P0442 has been added to alert one to a "small leak detected in the EVAP system".

Realizing that Wizard KNOWS about that which he speaks...and I DON"T...I still thought that a quick/cheap analysis might be in order...trying to keep DOWN the rising costs of replacing parts for diagnosis instead of for repair.

Good Luck !!!

 

[GTS Dean]

Nadine,

The evap cannister purge solenoid clicks at a regular interval. It meters in small amounts of fuel vapor to the intake manifold depending on a number of computer sensor inputs. Worry not.

 

[Nadine UK GTS]

Thanks Guys, you're a great help, this board is fab for fast response, and a reassurance to an overseas gal! Yes, trouble code was set on mil for EVAP, and that's why I went to check it out and I discovered it clicking! Now I know it's cool to click! Disconnected PCM for a few mins and all seems well / reset...check engine light out, phew!