vacuum-operated fast-idle actuator on an AAZ-style diesel pump

[jbturgeon]

Hi, i just bought a 95 golf 1.9td with the vacuum-operated fast-idle actuator on the pump. It's like if the vacuum thing is not working. When i plug a vacuum line directly from the main vacuum, it works and idle at 1200rpm and never goes down as nothing contro it. But when it is plugged like it should be, idle stays aroud 1000rpm all the time. The air is never sucked and fast idle never work on.

I am wondering if it could cause me some starting problem this winter (average of -20 in Québec!!). I was also wondering if the two small black boxes behind the fuel filter could be broken . They look ok but i really don't know what's going on with this kind of vacuum-operated fast-idle on this AAZ-style diesel pump.

Thx

[jbturgeon]

here is the image of my pump and i am talking about the black can in the upper left corner
http://forums.vwvortex.com/zerothread?id=4095739

[jbturgeon]

I will put more precision: my MK3 got AC and the fast idle is controlled with the vacuum. The problem is that there is no fast idle the way it is connected (by the two vacuum relay or smtg). I can't feel any suction when engine is cold/warm. I would like it to work but can't find any way. If it is not going to change anything on cold start, then i will leave it but i think it is there for something.

Thx

[gldgti]

hi mate,
there should be a vacuum solenoid over on the LHS of the engine bay under the turbo intake pipe. this solenoid should have many vacuum lines attached to it. some are supply from the vacuum pump, and the solenoid simply switches the circuits "open" or "closed" as required.

the solenoid is controlled byt the a/c switch and a coolant temperature switch... so when cold it should be switching vacuum to the idle controller, andlikewise for a/c on.

check that all the lines are good - best to replace them if they are old. you can check the solenoid valve with engine off - with ignition in on position, have someone turn the a/c on and off and check to see if the solenoid is opening and closing by blowing through the supply line.

good luck

[neimis]

It sounds like a '95 Golf (with air) is different than my '92 Passat (without air). On my car, if you follow the vacuum line from the diaphragm on the pump, it goes back to the firewall, over to the driver's side (in Canada) fender to an electrically controlled switch hidden behind the battery. The vacuum supply for the switch follows the same route, but goes directly to the check valve on top of the vacuum pump.

If you start at the diaphragm and check the hose for vacuum (while the car is cold - you have about 2 minutes from first starting the car, or, turn the air conditioning on), you can work backward to see where the vacuum stops. Make sure your electrical connections and wiring on the switch are good as well.

Just had another thought - I'm constantly correcting the vacuum lines that get screwed up whenever I take the car in to a garage for repairs, the mechanics mess up the lines all the time, they don't care how they are supposed to go. Maybe your vacuum lines are not attached correctly?