99 4.0 fuel pressure

[Hopper]

Pump replaced about 4 yrs ago with I think a Delphi, but knowing the shop that did it Im not a 100% on that. At the time is had a long crank and would die on the hwy. Pump and CPS was changed. Still had long crank but stopped dying on me. It has started dying everyone and a while again. Normally on the hwy and if I have less than a full tank.
Today I checked pressure
1. Hooked up gauge. 0 psi. Jeep sat overnight
2.primed pump. No crank 0 psi
3. Cranked 48 psi
4. Left cranked for a couple minutes. Psi went up a little to 49-50psi
5. Cut off jeep. Immediately went to 0 psi.
Any thoughts on what to do next?

 

[Hopper]

Forgot to mention CPS was replace again a couple months ago.

 

[macleanflood]

Couple of choices...you can replace the entire fuel pump assembly or you can just replace the pressure regulator on top of the assembly.

V

Thread 'How to replace your fuel pump without replacing the whole assembly'

Dec 21, 2021

Ok, I figured I'd post this here since I haven't seen it anywhere else. I've been chasing a hard start issue on my tj and got down to the in tank pump. I knew the sending unit was still good, but wanted the peace of mind of having a new pressure regulator and pump. I also didn't want to fork over ~$200 for a new assembly when I knew I could find a pump and regulator for much less. I didn't take pictures during the process because I'm a dumba$$ and this was the last thing I did on a Saturday so I was ready to be done. This only applies for 97-04 TJ's I believe. Assuming you've managed to...

• vrtillman
• Replies: 21
• Forum: TJ How-to Guides

• 

-Mac

 

[TJ Jim]

My pressure drops pretty quick too. But I don’t have any start issues

 

[TJ4Jim]

Your pressures are fine but it looks like your regulator is just passing back, no pressure cold is not an issue but it should not drop to zero immediately.

 

[Hopper]

Your pressures are fine but it looks like your regulator is just passing back, no pressure cold is not an issue but it should not drop to zero immediately.

Im going to test again tomorrow. But yeah it dropped to 0 as quick as turning the key off.