IT DOES NOT DRAW VACUUM FROM THE ATMOSPHERE, IT GET VACUUM PRESSURE FROM THE MANIFOLD OR SOMEWHERE ELSE ON THE INTAKE CREATING VACUUM PRESSURE FROM THE PISTONS PULLING AIR IN ON THE INTAKE STROKE OR IN A SUPERCHARGED ENGINE YOU NEED TO GET VACUUM FROM THE FRONT OF THE SUPERCHARGER SINCE YOU HAVE A POSITIVE PRESSURE INDUCTION SYSTEM RATHER THAN A NEGATIVE PRESSURE INDUCTION SYSTEM.
When I press the brake pedal, it is hard and difficult to start the car (on the next day)? but the brake can stop the car normally.... does anyone know the problem?
That sounds like a booster or a check valve. If you want to check the booster, start the car and let it idle for about 30 seconds to a minute until it builds brake pressure (vacume). Then apply the brakes and cut the car off. If your foot moves while the car is off, you have a bad booster and it's leaking somewhere. To test the check valve it's super easy, it's a one-way valve. Blow are in both ways. It should be blocked on one end of the valve, if not, then it's your check valve
i bought a new jegs brake booster and master cylinder, i renew all the hoses, drums, and pads with lines, and there is no any leaking, my engine is 4.3 stock with holley sniper 1. I wonder why it happened sometimes, for example i drove about 45 min without any problem, when i wanted to park my car, suddenly i lose a brake and become stiff and immediately i push it again came back to normal. I did all of your test and could not find problems, as i said sometimes it will happen.
Your intermittent brake issue could be due to a faulty brake booster or vacuum leak, so check the installation and connections. Ensure the master cylinder is properly bled and check for air bubbles or contamination in the brake fluid. Verify that the calipers aren’t sticking and that all brake lines are clear and properly connected. Also, inspect for any electrical or sensor issues if applicable. If the problem persists, consulting a professional mechanic for a thorough diagnosis might be necessary. Hope this helps. Good Luck!
Check your manifold vacuum. If you're not getting enough vac it may take a couple pumps to build. Especially after a a period of wide open throttle or heavy acceleration Hope this helps. If your not getting enough vac, check for leaks and ensure carb is dialed in.
It goes back to normal because it builds vac at idle. You can feel that when you first start a vehicle up. They take a few seconds to build vac at idle.
