Cadillac Repair/vacuum pump

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fixit wrote at 2012-12-29 19:24:27
I have 85 fleetwood gas type same type vacuum system. There are a number of vacuum circuits off the carb. The one you are talking about has vacuum off carb in series with vacuum pump. This supplies vacuum to the interior programmer to supply vacuum actuated controls for air, also emergency brake release. Also off same circuit vacuum is supplied to power brake booster as well as vacuum regulator to the EGR valve, and on to the Evap control valve. Leaky Evap will cause vacuum leaks as well.

The vacuum pump only assists the carb vacuum when low vacuum or off. It will not supply any additional boost vacuum. If open throttle or engine stall the vacuum will be supplied by the pump. Note if you have vacuum leaks it will affect the manifold vacuum level and the MAP sensor will see this a more fuel required and your fuel consumption will go up. Make sure you have absolutely no vacuum leaks or you will have a fuel pig car. Check hoses and worn out vacuum control diagrams as they age they leak. Air management is a good place for leaks.

This pump should turn on as soon as key is in RUN position. If not fuse is gone or pump has seized.


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Rob Painter

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Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

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Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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