Fuel pressure drop

[Oldguy]

2000 wrangler 2.5 SE I have a pressure gauge. key on engine off, jumps right up to over 40 then over a few seconds drops to zero. Should it hold and would this cause running issues. To start i have to prime once then start. Smell no leaking fuel, pump maybe?

 

[Steel City 06]

I'm pretty sure it should hold pressure regardless of whether the key is in the ignition. When you turn the key you should hear the pump kick on and off. But even once it's back off the pressure should hold for a while.

I would imagine there's a bad check valve or a leak somewhere. Since you don't smell fuel I would imagine it's somewhere in the sending unit

 

[Jerry Bransford]

2000 wrangler 2.5 SE I have a pressure gauge. key on engine off, jumps right up to over 40 then over a few seconds drops to zero. Should it hold and would this cause running issues. To start i have to prime once then start. Smell no leaking fuel, pump maybe?

At a minimum it should hold fuel pressure at least overnight if not weeks like mine does. The fuel pump has a check valve in it that when it leaks causes that problem.

You can buy a replacement Bosch fuel pump for $75 from Amazon that will replace the OE Bosch inside the fuel pump assembly. https://www.amazon.com/dp/B000BZL922/?tag=wranglerorg-20

Or for a little less at https://www.rockauto.com/en/catalog/jeep,2000,wrangler,2.5l+l4,1363430,fuel+&+air,fuel+pump,6256 in the Daily Driver section lower down the page.

Make darned sure to avoid the cheap brands like Spectre, Airtex, etc. which don't hold up for long. I had a Spectre fail at about 13 months. I'd go only with Bosch or perhaps Delphi.

The spec fuel pressure is 49 psi while the engine is running.

 

[Oldguy]

Ordered a Bosch pump and a fuel regulator. May as well replace both