I'd check the fuel filter and fuel pressure.
The engine does not produce enough vacuum to be usable.
The engine is the vacuum pump. All the vacuum operated accessories are operated by the vacuum supplied from the engine.
A gasoline engine makes it's own vacuum. The diesel engine has a vacuum pump next to the power steering pump.A gasoline engine makes it's own vacuum. The diesel engine has a vacuum pump next to the power steering pump.
The engine does not produce enough vacuum to be usable
think of it as a battery. it stores a large vacuum reserve while the engine is running. then its used whenever you use the device attached to it requiring the vacuum source. without it things like your heater and ac controls would not work properly because they require a large amount of vacuum to operate that your engine alone cannot supply fast enough.
The engine itself creates Vacuum once it is running.
i think voice cannot travel through vacuum.
You must have a diesel. The vacuum pump is what gives you POWER BRAKES and on the newer engines it also makes the power steering work. Only a gas engine makes vacuum. A diesel engine does not make vacuum, so they install a vacuum pump.
It's likely this vehicle has advanced technology and no longer uses an accelerator cable. It's called ELECTRONIC THROTTLE CONTROL and cannot be tampered with. If the engine idle speed is elevated and the "check engine" light is NOT active, it's common a small vacuum leak has developed.
The engine's vacuum is mostly controlled by the cam. You can use a milder cam to increase vacuum, or purchase an inexpensive vacuum reservoir to make better use of the vacuum you have.
Space is essentially a vacuum. Sound needs a medium to travel through to be heard. Therefore the sound of a rocket engine cannot be heard in space.
There cannot be any such thing as a vacuum of wavelengths!