in older cars like a model a Ford,
the carborator was gravity fed so perhaps .5 psi or zero uphill with a low tank
carborators and a fuel pump 5 psi is plenty to lift the gasoline 10 ' or so
with fuel injection about 100 psi is common
diesel can be about 1000psi fuel injected at TDC
The fuel pump pressure may vary by vehicle. However, on average the fuel pump pressure with the engine running should be between 4-6 psig.
While engine is running remove the fuel pump fuse. Engine will run out of fuel when pressure drops.
In most vehicles you can remove the fuel pump fuse or fuel pump relay as the engine is running, the engine will stall when the pressure is gone.
If the engine is not running the pressure should be 35 to 40 psi. If the engine is running the pressure should be 30 to 45 psi.
Fuel pressure (ignition key turned to on, engine not running): 50 to 60 psi
If engine is running then the answer is yes. And pressure will stay in the fuel line for some time after you shut the engine.
Remove the fuel pump fuse or relay while the engine is running. It will relieve most of the pressure once the engine has stalled.
With the engine running, remove the fuse or the relay for the fuel pump. The engine will stall soon and the fuel line won't have any pressure left.
Approximately 30
you need at least 50 psi to run and 55 or so to keep it running thats with cpi engine the others use less pressure and a different fuel pump....
50 to 85 psi engine not running. 25 to 35 psi engine running.
key on engine not running 58-64 psi engine running at idle pressure should drop by 3-10 psi