Fuel Injection Problem? - 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 05-15-2011, 04:43 PM
Thread Starter
Join Date: May 2011
Posts: 1
lnm510 is on a distinguished road
Fuel Injection Problem?

I have a 2002 4.0L TJ X. Problem is . . . I have to pump the gas to start the jeep. If I pump it before the first crank, it won't start. So, I crank it, pump the gas, then crank it again and it usually starts. I always thought that if a vehicle is fuel injected, you shouldn't have to pump the gas. Anyone got any thoughts?
lnm510 is offline   Quote
Old 05-15-2011, 05:13 PM   #2
Join Date: Aug 2008
Posts: 2,473
rrich is on a distinguished road
Pumping the pedal doesn't do anything. You don't have an accelerator pump like a carburetor to force gas in.

Try just turning the key on, wait 5 seconds, turn it off, then on again. Should start right up without touching the pedal. You may have to cycle the key one or 2 more times. The worse it gets, the more times you'll have to cycle it.

It's the check valve in the fuel pressure regulator on top of the tank that's going bad. It allows the fuel to drain back down the fuel line back to the tank.

When you first turn the key on, the pump only runs for 3-5 seconds, then stops. When the regulator is going bad, it doesn't get fuel all the way back up. Then when you crank it the pump runs again, eventually getting fuel up.

When you pump the pedal you are only letting in more air to the cylinders, making it too lean when the fuel finally does get up there, making it even harder to start.
The computer knows how much air and fuel it needs to start, let it do the thinking by keeping off the pedal.

It's no wonder the country is falling apart - stupidity abounds!
rrich is offline   Quote
Old 05-15-2011, 05:15 PM   #3
eugenesonrisa's Avatar
Join Date: Jul 2010
Posts: 169
eugenesonrisa is on a distinguished road
Try new spark plugs. Worked wonders for me.
eugenesonrisa is offline   Quote
Old 05-15-2011, 11:56 PM   #4
scot68's Avatar
Join Date: Apr 2011
Location: Mesa, AZ
Posts: 481
scot68 is on a distinguished road
Could also be 1 or more fuel injectors bleeding down. My 99 TJ 4.0L was having an issue with an "extended crank time" I had to cycle the key several times like rrich said to get it to start. I droped the tank and replaced the regulator first however that did not cure the problem in my case. Then I picked up a set of reman injectors (Bosch 4 hole) off Ebay and that fixed the problem. If you have a hand held fuel pressure gauge that's really the best way to diagnose.
scot68 is offline   Quote

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
Fuel Pump problem - help! dmw319 TJ Tech Forum 23 12-02-2014 10:14 PM
Injector cleaner castorj29 JK General Discussion Forum 71 03-07-2012 07:55 AM
Help with Fuel system problem! steamboattj TJ Tech Forum 6 02-18-2011 09:15 PM
AMC 401 fuel injection jeepers creepers CJ Tech Forum 4 08-13-2006 01:40 PM
TJ Error codes khenderson TJ Tech Forum 3 08-19-2005 12:36 AM

All times are GMT -5. The time now is 01:52 AM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 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
« Back

Enter your email address:

Delivered by FeedBurner