fuel pressure regulator???? - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today

Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 11-29-2011, 03:00 PM   #1
Join Date: Aug 2011
Posts: 3
Cool fuel pressure regulator????

2000 Wrangler, 4.0 .... plugs,wires,intake, throttle body all good (NO ENGINE LIGHT). Hard starting; go from "start" (failed attempt) to "on" then back to start, fires right up. Once a week or so, stalls at idle and shuts down .... cold or hot. Starts right back up.
Fuel pressure at manifold: key "on" .... immediate 47-48 psi then falling off after one second to 30 psi, bleeding down to 24-20 psi. Engine running .... 47-48 psi steady. Shut down engine, immediate bleed off in pressure to 25-30 psi then slowly bleed down to 18-20 psi.
Dealership sells only pump with regulator. Advanced auto sells seperate or together pump and regulator.
Feels like a fuel pressure regulator to me ..... advice as how to narrow it down????

tooright is offline   Quote
Old 11-29-2011, 03:28 PM   #2
my98tj's Avatar
Join Date: Aug 2005
Location: Tullahoma, TN
Posts: 585
i think you have narrowed it down to the pressure regulator. rockauto.com sells them for around $60.

Can anyone tell me how the flux capacitor is used to facilitate time travel?
my98tj is offline   Quote
Old 11-30-2011, 07:18 AM   #3
Join Date: Nov 2011
Location: Richmond va
Posts: 99
When you shut down the engine, it is normal to bleed off pressure. Any type of fluid pressure system will automatically start bleeding down when the pump is stopped, so that is not a big deal. What is interesting is when you are bleeding down from start up. I don't know what the normal PSI should be after start up, but my understanding of fluid dynamics, is that you will get a sudden burst in pressure at start up, and will slowly bleed down to a stable pressure. For a fuel injection system, I would think that anything from 30 to 60 PSI depending on the type of FI system you are using is not that far off from normal.
The interesting part is that the pressure will bleed off before you start the engine. The fuel pressure should stay high (47-48) when key is on, start up should be around the same, and then drop off. That is interesting that you are dropping at the "priming" point. I don't know if I would say that is a regulator problem rather more a pump problem. It seems that as the pressure builds it is pushing back against the pump causing the pump to slow down, almost like a backflow problem.
Just my two cents.
sfhusser is offline   Quote
Old 11-30-2011, 12:57 PM   #4
Join Date: Aug 2011
Posts: 3
Normal PSI should be 47-48 +/- 2 psi ..... There is no bleed down on pressure with the engine running; just when the ignition is put to "on" position (no attempt to start) does the pressure rapidly rise to 47 psi then drop off suddenly (1 second) to 25 psi or so.
Mechanic at dealership said pump will run for 3 seconds then shut down if no rpm detected. He also stated that once the pressure is up, there should be no bleed-down.
Disturbing as to why there is engine stalls every few days ..... unknown what fuel pressure is at time of stall as I am sitting at idle at a stop light 9/10 times.
Should not the pump be suppling pressure with engine running reguardless of regulator status???
tooright is offline   Quote

fuel pressure , hard start 4.0 , tj stalling

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Trouble shooting- no spark, no fuel pressure. Curro TJ General Discussion Forum 3 05-30-2011 06:45 AM
TJ died with no warning and no codes??? Keiger TJ Tech Forum 27 01-11-2011 09:04 PM
4.2 weber carb fuel pressure? yjtoddb YJ Tech Forum 0 11-16-2010 06:38 PM
Slow to build fuel pressure pumba General Jeep Discussion 0 08-04-2010 10:26 PM
Low fuel pressure with new fuel pump & filter crbnfbr YJ Tech Forum 0 11-08-2009 06:33 PM

Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 12:33 AM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC