Air in gas tank - JeepForum.com
 2Likes
  • 1 Post By Boojo35
  • 1 Post By bhartwell59
 
LinkBack Thread Tools
post #1 of 14 Old 01-27-2020, 09:13 AM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
Air in gas tank

Hey all,

Have an '87 w/the Mopar FI kit (external fuel pump) installed.

Just replaced the fuel lines coming off the 20-gallon plastic gas tank sending unit. Also replaced the 2 vent valves on top of the tank. Hooked up the vent hoses to the T-fitting.

Went to fill my tank afterwards and had air come out (vs in) when I took the cap off. It's happened a couple of times since then.

I'm thinking there must a blockage upstream from the tank. Check the evap canister?

Thoughts?

Thanks!


4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
Sponsored Links
Advertisement
 
post #2 of 14 Old 01-27-2020, 04:06 PM
Awesome
Registered User
 
Awesome's Avatar
1995 YJ Wrangler 
 
Join Date: Mar 2010
Location: Near Whacko
Posts: 3,931
Mine was doing that. Last time I had the Jeep on a lift I realized the return line was pinched between the tank and the body. I dropped the back of the tank and pushed the line back up on top of the tank. No idea if it's fixed yet, but it's something you might want to check.

The 4th 5-seater YJ in the world.
Awesome is offline  
post #3 of 14 Old 01-27-2020, 04:20 PM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
just crawled underneath it and decided to see if the vent hoses were clear... from the rear to the evap: air going and coming. from the rear to the vent valves/hoses nothing. so i'm thinking a pinched vent hose.

i'll double-check the return line while i have the tank dropped a bit.

BTW-the air that escapes out is pretty major.

thanks!

4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
 
post #4 of 14 Old 01-27-2020, 04:52 PM
Awesome
Registered User
 
Awesome's Avatar
1995 YJ Wrangler 
 
Join Date: Mar 2010
Location: Near Whacko
Posts: 3,931
Mine was building pressure just sitting there. It was doing it all summer, but I was driving it more often then too. I don't drive it regularly.

The 4th 5-seater YJ in the world.
Awesome is offline  
post #5 of 14 Old 01-27-2020, 05:14 PM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
i would have thought the air building up would be a venting issue... how would the return line cause that?

4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
post #6 of 14 Old 01-27-2020, 07:03 PM
Awesome
Registered User
 
Awesome's Avatar
1995 YJ Wrangler 
 
Join Date: Mar 2010
Location: Near Whacko
Posts: 3,931

The 4th 5-seater YJ in the world.
Awesome is offline  
post #7 of 14 Old 01-27-2020, 08:11 PM
ayelander
Registered User
 
ayelander's Avatar
1993 YJ Wrangler 
 
Join Date: Sep 2017
Location: Oak Island
Posts: 153
Garage
I have the same thing going on. Cant figure it out. I just leave the gas cap loose. I can do that with the 350 CID.

93 CTYJ, 350 Chevy, SM465, NP 231J TC, Ford 8.8 Rear, D30 with Chromoly, 4" RE Spring lift, 5/8" Boom, 1" body lift, 35" MT's
ayelander is offline  
post #8 of 14 Old 01-28-2020, 07:38 AM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
Ugh, all this because I needed to replace a cracked/leaking fuel hose.

I'll drop the tank a bit this weekend (again) and see what wonders await me.

4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
post #9 of 14 Old 01-28-2020, 03:52 PM
Awesome
Registered User
 
Awesome's Avatar
1995 YJ Wrangler 
 
Join Date: Mar 2010
Location: Near Whacko
Posts: 3,931
Quote:
Originally Posted by bhartwell59 View Post
Ugh, all this because I needed to replace a cracked/leaking fuel hose.

I'll drop the tank a bit this weekend (again) and see what wonders await me.
Yup, same. I replaced every fuel/vent hose except the two filler hoses. Afterward I was getting the tank pressure problem.

The 4th 5-seater YJ in the world.
Awesome is offline  
post #10 of 14 Old 01-28-2020, 05:20 PM
Boojo35
Registered User
1987 YJ Wrangler 
 
Join Date: Jul 2007
Location: Beer City
Posts: 2,311
Garage
The YJ tank has two vents that vacuum hoses connect to and a tee that connects them and goes forward to the canister. The way that the vent hoses are connected and routed, it is very easy to crush them or pinch them between the crossember that the front of the tank bolts to. If the lines to these were replaced and a generous amount of hose was used for instance ( which is common, they will sit forward of their intended place).This will pinch them between the forward crossmember mounting the tank and the tank itself. It is real easy to see if you drop the tank. The second is where the tank lines are routed above that crossmember through a rubber locating grommet can be crushed by bad body mounts, etc.
timatoe likes this.

If you cannot fix it with a hammer then it has to be an electrical problem.
Boojo35 is online now  
post #11 of 14 Old 01-28-2020, 05:58 PM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
That is precisely where I see my problem to be... that 3 hose holding "sandwich" between the crossmember and the tank. The rig runs so I know the fuel line is good and the return line went into that "sandwich" with little resistance.

It never occurred to me to check the vent line... and that's why I'm dropping the tank, partially, for the third time. Geez.

4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
post #12 of 14 Old 01-28-2020, 09:05 PM
timatoe
Registered User
 
timatoe's Avatar
1990 YJ Wrangler 
 
Join Date: Aug 2006
Location: Grass Valley
Posts: 17,788
I'd put money that it's pinched exactly like Boojo describe.

Quote:
Originally Posted by George Orwell
We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm.
timatoe is online now  
post #13 of 14 Old 02-02-2020, 08:00 AM Thread Starter
bhartwell59
Registered User
1987 YJ Wrangler 
 
Join Date: Sep 2007
Location: dallas
Posts: 334
Well, that was it... a folded over vent line going towards the front just past the T-fitting. Thanks all.

Back to our regularly scheduled program!
timatoe likes this.

4.2 '87 yj, 300,000+ miles, mopar mpi, 33" bfg mud KM2, skyjacker 4", 3.73 gears, arb lockers-f and r., tom wood's 2.07 sye conversion, tom wood's hd driveshaft, magnaflow cat/custom exhaust, 4wd rear bumper/swing-out tire carrier
bhartwell59 is offline  
post #14 of 14 Old 02-02-2020, 08:33 AM
Boojo35
Registered User
1987 YJ Wrangler 
 
Join Date: Jul 2007
Location: Beer City
Posts: 2,311
Garage
Thanks for the report. Good to hear that it is fixed.

If you cannot fix it with a hammer then it has to be an electrical problem.
Boojo35 is online now  
Reply

Quick Reply
Message:
Options

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

Password:


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



Email Address:
OR

Log-in











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