Once the engine stops, how does the fuel rail lose pressure? Does the fuel have to backtrack through the feed line, filter and pump? If so, what determines the rate at which the pressure is returned to zero? Mine drops to 30 when the engine stops then SLOWLY (over two hours) goes down to 20 then a day to get to zero. Seems to me that injectors would be less prone to leak if the pressure was relieved quicker.
How does the fuel rail lose pressure?
- Thread starter JoelGN
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I could mostly going back through the pump checkvalve. If you pinch the return line tight though, it means your injectors are dripping fuel into your motor slowly over time dropping the pressure, this is how you do a leakdown test.
If the check valves are working, and the injectors don't leak, the fuel rail won't lose pressure. If it loses pressure too quickly, then something is wrong, and you should fix it. (or think about fixing it 
)There is a check valve in the pump, that prevents fuel from going back through the pump. If it leaks, then the rail will lose pressure. If an injector leaks, the rail will lose pressure, and some fuel will end up in the cylinder with leaky injector. The third possibility is that the fuel pressure regulator doesn't shut off. The regulator should shut off low when the pressure reaches the regulator set point, but they don't always seal completely. You can find the leak by squeezing the rubber hoses. Squish the return hose, and pressure holds, means the regulator is leaking. Squish the supply hose, and the pressure holds, means the pump check valve is leaking. Squish both hoses, and pressure still drops off, means one or more injectors is leaking.
)There is a check valve in the pump, that prevents fuel from going back through the pump. If it leaks, then the rail will lose pressure. If an injector leaks, the rail will lose pressure, and some fuel will end up in the cylinder with leaky injector. The third possibility is that the fuel pressure regulator doesn't shut off. The regulator should shut off low when the pressure reaches the regulator set point, but they don't always seal completely. You can find the leak by squeezing the rubber hoses. Squish the return hose, and pressure holds, means the regulator is leaking. Squish the supply hose, and the pressure holds, means the pump check valve is leaking. Squish both hoses, and pressure still drops off, means one or more injectors is leaking.28 hours after shutting the engine off and there is 15#. This indicates something is SLOWLY bleeding off pressure. If its the regulator or pump check valve, no problem. If its one or more injectors, problem. I'll try the squeezing the supply and feed lines. Removed the three easiest plugs (1, 2 and 4) and all looked/smelled fine. The problem is that my oil developes a gasolinish odor after around 200 miles so bearings may be jeopardized. Thanks for your replies.
a tool such as this
fuel pincher
fuel pincher
