Fuel Pressure - JeepForum.com
LinkBack Thread Tools
post #1 of 3 Old 08-11-2013, 12:08 PM Thread Starter
Registered User
1989 YJ Wrangler 
Join Date: Apr 2013
Location: Layton
Posts: 16
Fuel Pressure

First---89 YJ with 93 HO 4.0---Jeep runs great once started.

I've had this problem since I bought my jeep and thought it was time to fix. I have to prime the pump 2 cycles and then shortly turn the motor once and back off then it will start. The pump will only cycle approx .5 seconds before stopping. I checked the fuel pressure and all was good while running but as soon as the key goes to off, it drops immediately to zero. Changed the fuel press regulator but no fix. Thought the check valve in the fuel pump was probably bad. Dropped the tank and changed the pump. Still drops to zero immediately and the prime cycle is still about a half a second.
Ive read on hear that a pressure drain over a couple minutes is a leaking injector but mine is instant.

Why is the prime cycle so short and why does my fuel pressure drop so fast? There are no leaks between the pump and the fuel rail.

Hilblee is offline  
Sponsored Links
post #2 of 3 Old 08-12-2013, 03:02 PM Thread Starter
Registered User
1989 YJ Wrangler 
Join Date: Apr 2013
Location: Layton
Posts: 16

Ive owned 74, 75, 76 and 79 CJ-5s. 76 J10 (prob the best jeep ever) 89 YJ (current) and a 98 TJ. I consider all of them "Money Pits" Always throwin money at em whether they need it or not!
Hilblee is offline  
post #3 of 3 Old 08-12-2013, 04:11 PM
Registered User
1992 YJ Wrangler 
Join Date: Mar 2009
Location: Neosho
Posts: 956
We have very different equipment ('92 2.5L MPFI here), but mine also has a very short prime (like yours). As for the immediate pressure drop ...it sounds like you've already addressed any suggestions that I would've made.

“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values
GrantYJ is offline  

fuel pressure , fuel pump , pressure regulator

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may 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 On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome