fuel pressure specs?

If it's like the 93 ZJ....

31-32. Will bump a 8-10 psi higher if you pull the vac line off the pressure regulator.

What's more important is pressure at speed. Most of the time it's a plugged fuel filter. You can still get good pressure at idle, but the volume sucks.

If it's like the 93 ZJ....

31-32. Will bump a 8-10 psi higher if you pull the vac line off the pressure regulator.

What's more important is pressure at speed. Most of the time it's a plugged fuel filter. You can still get good pressure at idle, but the volume sucks.

Thanks. I changed the filter about 500 miles ago when this first started to act up. Put the fuel pressure gauge on it last night and taped it to the hood so I could watch the pressure on the way home. Runs about 22 psi, but when I give it gas, drops to about 19 and starts to cut out. Also, not going up when I pull the vac line to the regulator. Guess I know what I'll be doing this weekend.

22 psi, but when I give it gas, drops to about 19

You say removing the vac line does nothing? If you put a vac gauge on that hose does it give you a vac?

- just to make sure the hose isn't leaking -

If the hose has vac then you likely need a new pressure regulator since when they leak/bypass you get exactly what you are seeing.

May as well replace the two O-rings when you do. Otherwise the little bastard will leak. Rings go in the rail, apply some oil, then slide the regulator body in.

Had a leak at the reguator a couple years back.

Had to replace my fuel pump about a year ago. But when it went I didn't have jack for pressure. 3 psi!

Oh. A new regulator usually comes with rings. Just make sure.

Rings are about 4$ or so.

Regulator is a "bit" more. $76 at Napa CRB 219679

Oh. A new regulator usually comes with rings. Just make sure.

Rings are about 4$ or so.

Regulator is a "bit" more. $76 at Napa CRB 219679

Oh. A new regulator usually comes with rings. Just make sure.

Rings are about 4$ or so.

Regulator is a "bit" more. $76 at Napa CRB 219679

Yep, max pressure with the return line pinched should be close to 72psi. At lest your prices are close, the pump assembly in my ZJ ran about $200!

FWIW, It seems your pump lasted about as long as mine did. 1993-2010

And I have no idea why I brainfarted.

Another test for a bad reg is to just watch the fuel rail pressure after priming/running the pump. If it falls then the reg is leaking (little bitty leaks can also be dribbling injectors).

And that can be a slooowww drop - I can't put my eyeball on the spec right now but my somewhat frail memory says that (assuming the proper 31 PSI pressure to start with) the limit is 19 PSI after something like 10-15 minutes. My 88 I6 will hold 10+ PSI overnight!

Often dribbling injectors will give a hard start because of flooding issues.

And that can be a slooowww drop - I can't put my eyeball on the spec right now but my somewhat frail memory says that (assuming the proper 31 PSI pressure to start with) the limit is 19 PSI after something like 10-15 minutes. My 88 I6 will hold 10+ PSI overnight!

What you're seeing would be expected. With a 31psi regulator, it's not going to bypass if there's less than that available from the pump.