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16

There are several methods to detect vacuum leaks of unmetered air into the fuel delivery system One method is to use soapy water in a spray gun. The real issue here is how are you going to detect a vacuum leak and how do you know you've found it. What is a vacuum leak in this context related to a fuel delivery system? Unmetered air in a fuel system is ...


14

One tool overlooked here is an ultrasonic leak detector. They work by listening to the noise of a leak. Obviously they would be better used in a totally quiet environment, but it's a possibility. I've used them to determine automotive refrigerant leaks, and for water leaks from outside to inside the passenger compartment of a car. For vacuum, dunno ...


10

Some people have stated listening for a vacuum leak noise and if located within a vicinity disconnect and add a new line of the same diameter and get a cigar and blow smoke from the cigar in the line. After blowing smoke in the new line cork the end and look around to see if any smoke is coming through. If you don't smoke you could always look into getting ...


9

Vacuum is the opposite of atmospheric pressure. The atmosphere at sea level holds at about ~14.7psi. This is considered "1 atmosphere" or "1 bar". The engine is an air pump. It draws air in and pushes exhaust out. More accurately, it doesn't "draw" air in, but rather, creates a vacuum and the atmosphere pushes air into the space with vacuum in an attempt to ...


8

@DucatiKiller gives a very good assessment of how to look for leaks. Using these same efforts, you can also use gas from a propane torch around the same areas described. When the gas finds a vacuum leak, you'll find a definite change in engine RPM due to the fuel which is found. Mind you, you are opening the valve and using the gas itself, unlit. You don't ...


8

One other way to look at this, sort of from a different direction. As I get older I really like being able to do more with less and do so safely. I think its sometimes awesome that an old guy with barely any tools can out perform the young guys with an expensive tool box. (And yeah, I used to have many of those tools... now I'm trying to downsize a bit.) I ...


8

This is how I diagnosed a vacuum leak in my car. I removed the air filter from the intake pipe (mine was a turbocharged lancer evolution with an after market intake pipe) started the car. (Make sure your surroundings is not dirty and is very quiet). After starting the vehicle, I placed a book to block the air being sucked into the intake pipe (do not place a ...


7

Another way that has not yet been mentioned is artificially creating a vacuum or pressure in the intake. Vacuum is naturally there when the engine is working, but often the iconic hissing sound a leak makes is overwhelmed by the natural sounds of a working engine in the case of tiny leaks. If you reproduce the vacuum or create pressure with the engine off - ...


6

You can put a plug in the vacuum line or put a cap over the port at the other end of the line. Ask for Vacuum Caps. Note: The air injection system on my car is much more than just the smog pump. I think you should try to understand the operation of the system before you try to remove.


6

There are usually two parts to this diagnosis: Establish that you have a vacuum leak If confirmed, find out the source of the malaise Confirming the presence of a leak My favorite trick to establish the presence of a vacuum leak involves physically blocking the air intake(s) using your hands or something suitable. It usually helps to remove the air filter(...


6

If it's a vacuum leak, it will be sucking in air, and you'll probably be able to hear it. With the rest of the engine making noise, using something to pinpoint the sound would help: Take a piece of rubber hose and hold one end up against your ear, moving the other end around the engine listening for the hissing/sucking sound. It's kind of like using a ...


5

Engine gauge vacuum is the difference between manifold pressure and atmospheric pressure. When you snap the throttle pressure builds in the manifold. Then settles back down to whatever it was at before. If you look at a MAP pid it correlates with engine gauge vacuum. A shakey needle on a gauge would suggest a problem with the valve train. Either they need ...


5

I've used a stick of burning incense. Cheap and simple!


5

On the 97 Sonoma the controls are electronic and send a signal to a vacuum switch block which will send vacuum to various valves. This is from a corvette but is similar. While the switches on the control panel can fail more commonly the vacuum lines, check valve or vacuum reservoir will fail first. Locate the vacuum source line and measure engine vacuum. ...


4

A few comments in addition to David's answer: You can be creative with how the vacuum hose is closed off Something as simple as a bulldog clip will do - the purpose is to seal off one end. Another more permanent solution would be to remove the hose and weld the nipple shut Don't forget the other holes resulting from a smog pump delete There are other ...


4

After doing some research, I think I found your part. See diagram below: You can see that the little T-junction is part of the PCV hose assembly (item 21 in the diagram). Unfortunately, this means you can't source the part separately, you'd need to buy the whole PCV hose. The part number of the PCV hose is 96474643.


3

Heck yeah! Short answer: Replace the check valve. Long answer: There is a check valve between the vacuum reservoir and the rest of the system. What that does is help the vacuum reservoir hold more vacuum. Your engine won't have enough vacuum "force" to move the heating ventilation doors without the reservoir. The check valve is that little black and ...


3

This may assist in diagnosis May not be an answer for you but you mentioned; The spark plugs are burned at the tip. The definition of burned is important to your diagnosis. If burned means the electrodes are eaten up a beat you could be suffering from a lean condition from a vacuum leak or a sensor not reporting properly to the ECU. IF you have a CEL (...


3

Hard to say with the information given. Sounds like retarted timing or not enough air or fuel (too rich / lean) . A repair manual will be infinitely useful in testing/troubleshooting. Things to test: codes, even if the CEL isn't on there might be something stored. air filter spark plugs (clean, gapped correctly) wires cap rotor coil vacuum lines (check ...


2

There are valves involved that operate when pressure is applied or removed from the brake pedal. Have a look at these simplified diagrams - http://www.agcoauto.com/content/news/p2_articleid/129


2

From your description, I doubt anything you've stated is at fault. I would bet the vacuum port you used for testing is associated with another device which is where you heard the "ticking" sound. As this alternate device is turned on/off, it is causing the wild vacuum readings you are seeing. If I were to guess, I would think you are probably reading ...


2

Did you try plugging the business end of the solenoid? I checked vacuum before and after the valve and at the main line to the heater control behind the glove box. With the valve disconnected and the line plugged I have good vacuum. With the valve in place normally I have poor vacuum at most all points. Problem is I don't have any real way to check the ...


2

Its fine if you drive it, but you might want to get it fixed as soon as possible, because it decreases the power of your vehicle and it could possibly harm your engine.


2

At the HVAC Control Switch: full vacuum measured at source hose able to manually operate all three actuators using a vacuum pump hissing sound from a vacuum leak Using a stethoscope, I narrowed the leak down to inside the switch itself, which was only just changed a couple months ago. It's being replaced under warranty. EDIT: Changed the HVAC Control ...


2

First, verify the vacuum gauge and the port you are connecting to. 5in is very low vacuum and I suspect the car would idle like crap. Vacuum is produced by the engine efficiently trying to pump air and the carburetor choking it off. Engine condition (piston, rings, heads), timing chain (advanced/retarded) affect how much vacuum it produces. Ignition ...


1

I remember that gauges were available for tuning / performance fitment : id est : boy racer / petrol head applications and the gauges came with an explanation sheet which explained the readings or fluctuations, but this was, as you point out, for carburettor applications. I have not seen any documentation that refers to the use with fuel injection setups - ...


1

I don't know if it's a very sophisticated kind of hose, but I'd just use some generic hose. You can probably reuse the one-way valve. It's there to maintain the vacuum in the servo when the manifold pressure gets high. Make sure the hose is tightened well with hose clamps, you don't want to suddenly lose your brake boost while you're not expecting it. The ...


1

Hard to say exactly what is it, but I would troubleshoot using a stethoscope. Have someone sit in the car, set the emergency brake, hold the brakes, and put it in drive. Might want to block the tires too just to be extra sure. The stethoscope will allow you to find the exact location of the sound. Look around the intake hoses, throttle body, intake ...


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