200 ZJ fuel pressure???

Markhousen did pass the time by typing:

32psi for the 93ZJ 4.0 Yours should be similar but since they changed in 2000 can't say for sure.

The older 4.0 spec'd 40 PSI w/o engine vacuum, 32 PSI with vacuum but what ever the number I'd like to know where the 10 PSI overnight leak down value comes from. I KNOW I've seen it somewhere but the FSM I have only says no more than a 10 PSI droop sitting off for 10 minutes. Even with the older unit I have I still have 15 PSI or so after sitting for a day but I would sure like to find the source if that is a spec for overnight leakdown.

Will Honea did pass the time by typing:

I need to update that part of my site with better info.

Vac line connected: 31psi Vac line disconnected: 39psi Return line pinched*: 75psi within 2 seconds

• Don't pinch hoses for longer than 5 seconds

The bleeddown has three basic tests depending on what you clamp off and where you measure.

- leaking injectors

- bad check valve in the tank

- leaking fuel pressure regulator

For the most part they refer to a leakdown of

20psi or less within 30 min as being acceptable.

Don't see any overnight test for leakdown. Seems kind of silly since that's why the pump cycles as you turn the key past on.