I have a 98 Grand Cherokee with the 6 cyl that is having hard starting problems. I checked fuel pressure while running and it is within spec (44 psi). However, as soon as the engine is shutoff the fuel pressure immediately drops to 0. When turning the key to on I can hear the pump run and the gage needle jumps slightly but it never builds pressure.

I don’t have the test rig to go between supply line and the fuel rail. I know that is part of the leakdown test to narrow down whether the injectors are leaking or if the problem is back in the tank. But a note in the leakdown procedure also says that a quick loss of pressure indicates a defective check valve in the filter/regulator. This model is a returnless system with the regulator and pump both in the tank. What are the chances that the injectors are leaking? Do both the regulator and fuel pump have check valves in them? If so, it sounds like one those check valves is the problem. Is there any way to determine if it really is the regulator and not the fuel pump? Thanks!

 

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