Fuel system - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 08-30-2013, 06:01 PM Thread Starter
Keyboard Implanted
 
thorjeep's Avatar
 
Join Date: Jan 2000
Location: In the process of finding it
Posts: 2,559
Thanks: 0
Thanked 1 Time in 1 Post
 
Fuel system

Driving me nuts.

1985 4.2L CJ7 with Hesco MPI (1994 YJ converted to fit 4.2).

Been having cut-out, etc in hot weather.
Replaced:
Elec. Fuel Pump
Fuel Filter
Lines to filter from tank
Checked tank, pickup, float, all good.

Re-positioned fuel pump lines to go on passenger side, to avoid exhaust on drivers side. Lines are good, not crimped. Pump is high, near the wheel well.

Problem: Sometimes when I start it, it seems to take a long time to get fuel pressure. There is gas in the line at the rail fine, and the pump sounds like it is pumping air for the 20sec it takes to get the fuel pressure to raise.

Question: Anything create air in the lines up to the pump intermittently? I parked it last night for an hour and it took 20 sec to get pressure. I Started it this morning and instant pressure, it jumped to 10psi when the computer ran the initial pump when the key is tuned to on.

Scott
1985 CJ7 T.H.O.R

"He brought me up out of the pit of destruction, out of the miry clay, And He set my feet upon a rock making my footsteps firm."
-Psalm 40:2
thorjeep is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 08-31-2013, 09:54 AM
Moderator
 
Jim_Lou's Avatar
 
Join Date: Dec 2001
Location: Belleville, Illinois
Posts: 11,449
Thanks: 15
Thanked 16 Times in 11 Posts
         
A tiny leak in the connections at the pump or the tank could cause that. Since it's not dripping gas, it would be at the tank or on the intake side of the pump. If air gets into the line and the gas drains back to the tank the pump has lost its prime and takes a while to get going again.

Just a guess.

EVERYTHING's easy for the guy who doesn't have to do it.
B. Dash Fabrication
Jim_Lou is offline  
post #3 of (permalink) Old 09-18-2013, 09:11 AM
I Might Just Know What I'm Talking About
 
jdoggmoney's Avatar
 
Join Date: May 2003
Location: Nebraska
Posts: 1,805
Thanks: 0
Thanked 1 Time in 1 Post
 
Has the pump always been "high"? Maybe in an effort to get it away from the heat you compromised its ability to pull fuel from the tank, or at least get primed. I would try to get it as low as possible and still be out of danger. Most electric pumps are "pushers" and although they will pull and prime to a certain extent, they aren't designed for it.

Is this the only hammer you've got?
jdoggmoney is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 09-23-2013, 04:57 PM
Addict
 
Join Date: Jun 2007
Location: Southern Maryland
Posts: 363
Thanks: 0
Thanked 1 Time in 1 Post
 
I ran the same setup on my 1986 for over 10 years and 1K mikes. Had no problems whatsoever, I would bet money if you installed the pump as close to the tank as you can it will eliminate all the problem. I just kept my pump and went to the junk yard and found a 1990 YJ with a 15 gallon tank already set up for fuel injection and modified it to work in my CJ. I'm doing a 1989 YJ with the 4.2 and that is just one of two things left to get, to do it. Anyway move the pump to where it says in the directions and that should do it. And, if your directions told you to put it there I have my original directions from Hesco and they said to install it on the crossmember just right in front of the tank cause I still have the clamp they included with the kit. Just my .02 cents.
Booger is offline  
post #5 of (permalink) Old 10-22-2013, 08:48 PM
Keyboard Implanted
 
Rio_Grande's Avatar
 
Join Date: Jun 2000
Location: Southeastern Indiana
Posts: 4,766
Thanks: 3
Thanked 2 Times in 2 Posts
 
Thor I don't claim to know or understand your setup, but a few years ago my wife's ford explorer had an anti back flow valve go out and it would allow fuel to drain back. The pump was in the tank, but that 10 inch straw would take about 15 seconds to pump up to pressure. 4.00 part took about 5 hours to put in.

Ya only go around once, best to enjoy it the first trip.
Rio_Grande is offline  
post #6 of (permalink) Old 11-08-2013, 11:20 AM Thread Starter
Keyboard Implanted
 
thorjeep's Avatar
 
Join Date: Jan 2000
Location: In the process of finding it
Posts: 2,559
Thanks: 0
Thanked 1 Time in 1 Post
 
Thanks Guys,

1. It seems to be working now after replacing the pump, though of course temperatures are cooler. In 8mos I may re-open this.

2. I have seen in my research a small, low volume pump that has high flow through rate (Won't restrict the current pump) between the tank and the current pump will solve this problem in race cars. For $35 I may try that next.

Scott
1985 CJ7 T.H.O.R

"He brought me up out of the pit of destruction, out of the miry clay, And He set my feet upon a rock making my footsteps firm."
-Psalm 40:2
thorjeep is offline  
post #7 of (permalink) Old 11-08-2013, 05:49 PM
Moderator
 
Jim_Lou's Avatar
 
Join Date: Dec 2001
Location: Belleville, Illinois
Posts: 11,449
Thanks: 15
Thanked 16 Times in 11 Posts
         
It sure doesn't seem that another pump should be necessary if the first one is installed and running properly. But . . .

EVERYTHING's easy for the guy who doesn't have to do it.
B. Dash Fabrication
Jim_Lou is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

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

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









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.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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 On
Pingbacks are On
Refbacks are On

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