Fuel Supply cutting out - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Fuel Supply cutting out

ECGS Black Friday Sale!!6th Annual, Beat Your Wife to the Credit Card Sale!50 in light bar /A pillar mount less than 500 at JeepHut.c

Reply
Unread 08-19-2011, 09:01 PM   #1
crazy8x4o5
Registered User
1978 CJ7 
 
Join Date: Apr 2011
Location: Fort Polk, LA
Posts: 120
Fuel Supply cutting out

I know this subject is beat to death. I remember seeing a good thread a few months ago that fit my profile but I cant find it now.

the Jeep starts easy and runs great to drive around town but anytime I run for more than 30 or 45 min at a time, especially when it's hot out, it starts to kick and buck at me. the most recent I drove it about 140 miles, and the symptoms started at about 50miles from the house. It started sputtering and kicking and all the classic signs of running out of gas. I pulled into a parking lot and popped the hood, I cranked it and had no fuel flowing through the inline filter.

I pulled the inlet line to the mechanical fuel pump and blew through it to make sure it was clear and it was. When i got everything hooked back up, after a few seconds cranking I was getting fuel again. she started up and down the road we went.

Things were great for about twenty miles and then she started cutting out again. I would limp her as far as possible feathering the gas and just when I'm about to give up the problem would go away.. for a few minutes!! after that the cycle repeated every 10-15 miles.

It seamed though that if I let off the gas and then eased slowly back into it repeatedly, that problem would go away. at least that's the way it seemed.

Anyone have similar issues?

crazy8x4o5 is offline   Reply With Quote Quick reply to this message
Unread 08-19-2011, 09:03 PM   #2
BioTex
Registered User
2006 TJ Wrangler 
 
Join Date: May 2008
Location: Alpine, Tx.
Posts: 3,173
Is your cap vent plugged? Try loosening it, and see if still happens.
__________________
'85 CJ7, BDS 4" lift, 1" Body lift, 33x12.5, Shrockworks Sliders, 304 V8 with RV cam., T-176, D300, Dana 30, AMC 20.
1986 CJ10-A SD-33 Diesel/727/np208
1971 800B with 345/T-19
06' TJ Rubicon, 4" R.C. springs, BFG/AT 35s M.C. 6" fenders, rockers and surrounds, Currie front & rear adj. tracbars, tattons DC rear shaft, adj. upper - lower CA's. Bilstein 5100's
YJ Buggy Build Current project. Stroker/FI ?
1990 MJ Comanche 4.0L AX15/np231
BioTex is offline   Reply With Quote Quick reply to this message
Unread 08-19-2011, 09:03 PM   #3
crazy8x4o5
Registered User
1978 CJ7 
 
Join Date: Apr 2011
Location: Fort Polk, LA
Posts: 120
btw I'm working with a 304 with a MC 2100 series carb and motorcraft ignition
crazy8x4o5 is offline   Reply With Quote Quick reply to this message
Unread 08-19-2011, 09:04 PM   #4
crazy8x4o5
Registered User
1978 CJ7 
 
Join Date: Apr 2011
Location: Fort Polk, LA
Posts: 120
Quote:
Originally Posted by BioTex View Post
Is your cap vent plugged? Try loosening it, and see if still happens.
Thats the first thing I checked because I new I wasnt out of gas. I am getting no pressure release when I loosen the gas cap
crazy8x4o5 is offline   Reply With Quote Quick reply to this message
Unread 08-19-2011, 09:06 PM   #5
BioTex
Registered User
2006 TJ Wrangler 
 
Join Date: May 2008
Location: Alpine, Tx.
Posts: 3,173
If it is not vapor locking, then I'd have to say the pump is bad.
__________________
'85 CJ7, BDS 4" lift, 1" Body lift, 33x12.5, Shrockworks Sliders, 304 V8 with RV cam., T-176, D300, Dana 30, AMC 20.
1986 CJ10-A SD-33 Diesel/727/np208
1971 800B with 345/T-19
06' TJ Rubicon, 4" R.C. springs, BFG/AT 35s M.C. 6" fenders, rockers and surrounds, Currie front & rear adj. tracbars, tattons DC rear shaft, adj. upper - lower CA's. Bilstein 5100's
YJ Buggy Build Current project. Stroker/FI ?
1990 MJ Comanche 4.0L AX15/np231
BioTex is offline   Reply With Quote Quick reply to this message
Unread 08-19-2011, 09:12 PM   #6
crazy8x4o5
Registered User
1978 CJ7 
 
Join Date: Apr 2011
Location: Fort Polk, LA
Posts: 120
if so its the 3rd one in 6 months with less than 700 miles in that 6 months. I new the original pump was bad. the second I dont think was bad, we replaced it before we descovered that the timing chain was loose and replaced that as well as the whole ignition system in the process.
crazy8x4o5 is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 12:33 AM   #7
82JeepCJ7
Registered User
1982 CJ7 
 
Join Date: Jun 2010
Location: Marysville, WA
Posts: 4,983
What fuel are you running? If it has ethanol in it, it is the cause of your problem. Go here http://pure-gas.org/index.jsp and try running a couple of tanks of fuel with no ethanol in it through the system. It should clear up.
__________________
Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
82JeepCJ7 is online now   Reply With Quote Quick reply to this message
Unread 08-20-2011, 12:33 AM   #8
82JeepCJ7
Registered User
1982 CJ7 
 
Join Date: Jun 2010
Location: Marysville, WA
Posts: 4,983
What fuel are you running? If it has ethanol in it, it is the cause of your problem. Go here http://pure-gas.org/index.jsp and try running a couple of tanks of fuel with no ethanol in it through the system. It should clear up.

El Cheapo out in Richmond Hill has ethanol free gas.

How ya liking Ft Stewart? I spent 3 years at Hunter.
__________________
Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
82JeepCJ7 is online now   Reply With Quote Quick reply to this message
Unread 08-20-2011, 07:23 AM   #9
BioTex
Registered User
2006 TJ Wrangler 
 
Join Date: May 2008
Location: Alpine, Tx.
Posts: 3,173
Quote:
Originally Posted by crazy8x4o5 View Post
if so its the 3rd one in 6 months with less than 700 miles in that 6 months. I new the original pump was bad. the second I dont think was bad, we replaced it before we descovered that the timing chain was loose and replaced that as well as the whole ignition system in the process.
This would have been nice to know information in your first post ya think?
Good luck.
__________________
'85 CJ7, BDS 4" lift, 1" Body lift, 33x12.5, Shrockworks Sliders, 304 V8 with RV cam., T-176, D300, Dana 30, AMC 20.
1986 CJ10-A SD-33 Diesel/727/np208
1971 800B with 345/T-19
06' TJ Rubicon, 4" R.C. springs, BFG/AT 35s M.C. 6" fenders, rockers and surrounds, Currie front & rear adj. tracbars, tattons DC rear shaft, adj. upper - lower CA's. Bilstein 5100's
YJ Buggy Build Current project. Stroker/FI ?
1990 MJ Comanche 4.0L AX15/np231
BioTex is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 07:58 AM   #10
elboe805
Registered User
1986 CJ7 
 
Join Date: Mar 2011
Location: memphis, tn
Posts: 47
I was having a similar problem with my CJ7 a few months ago... It turns out the cam gear that powered the mechanical fuel pump was rounded off and it wouldn't consistently pump. Get a chevy block off plate for the mechanical mount and get yourself a holley red. 600 miles on mine so far and nothing so much as a sputter; plus much faster cold starts. Make sure you run it through your oil pressure relay for safety. Replace your gas cap and check your lines, especially the tank return line. It sounds like vapor lock-
elboe805 is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 10:05 AM   #11
littlebuddie
Registered User
1980 CJ7 
 
Join Date: Dec 2007
Location: Oregon
Posts: 674
Quote:
Originally Posted by elboe805 View Post
I was having a similar problem with my CJ7 a few months ago... It turns out the cam gear that powered the mechanical fuel pump was rounded off and it wouldn't consistently pump.
That's what I was thinking. What's the chance of that happening?
__________________
1980 CJ-7 258 Dana 300, SR-4 Trans, Basically Stock Except One Piece Rear Axles, Weber Carburetor.
*[\`\]*
O\lllll/O

[]=O=[]
littlebuddie is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 10:26 AM   #12
h2ogun
Registered User
2006 TJ Wrangler 
 
Join Date: Aug 2011
Location: Texas, Texas
Posts: 218
Having had the same problem, It can be many things.

Start here.

Fuel Filter:
Make sure you fuel filter is oriented correctly. The return line (the small one) should be directly above the larger line going to the Carb. Not having it exactly like that can cause vapor lock.

BTW, ever time I put this picture in some self-righteous JERK will criticize the photo because the filter is not level. When I took the photo, I propped up the lines for better clarity and the camera is angled.........If you dont like the photo, put your on dram photo in.

Fuel Pump:
Get a vacuum/pressure gauge, "T" it into the line between the fuel pump and carb. You should have 4-8 psi of pressure. If not, pump is bad.

Fuel line from the tank:

Remember you have a jeep that is 33-34 years old and the fuel line may be that age too. Check to see if you have any leaks in the line. Look at both the line and connections.

While involved, the best way I can think of checking the line is to temporally install an electric pump as close to the tank as possible. Pump fuel toward the engine. (when I did this, it looked like I had a drip system and a couple of squirts under my jeep) If it is dripping or squirting you have bad connections or holes in you line. Fix or replace. Remember the mechanical pump sucks the fuel from the tank. If there is a hole or a bad connection, it will suck air from that point and it will act like running out of fuel. Getting hot makes the problem worse. Less fuel more air in the line will enhance vapor lock. Work of caution, this procedure may create a fire hazard, take precautions.

Fuel line above the tank:
The ribber line may have been there from the factory. It will get old and crack. You may need to drop the tank and replace the line. If you drop the tank, search this forum, there are numerous write ups on it, not necessary to put in this post and covers other precautions you should be aware.

Vent the tank:
As noted by Biotex, crank the gas cap to relieve a vacuum. You will hear a "hiss"

I have done all the above and it solved my problem. I am running the same engine and carb.

Good Luck
Dif

Last edited by h2ogun; 08-20-2011 at 11:55 AM..
h2ogun is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 06:21 PM   #13
crazy8x4o5
Registered User
1978 CJ7 
 
Join Date: Apr 2011
Location: Fort Polk, LA
Posts: 120
the last two fuel ups were with fuel that was 10% I try to find a station close with no ethanol. as far as the fuel lines go I've checked them all. My setup doesnt have a return line from the filter
crazy8x4o5 is offline   Reply With Quote Quick reply to this message
Unread 08-20-2011, 07:40 PM   #14
elboe805
Registered User
1986 CJ7 
 
Join Date: Mar 2011
Location: memphis, tn
Posts: 47
Quote:
Originally Posted by crazy8x4o5 View Post
My setup doesnt have a return line from the filter
It should... Sounds like you're building up too much pressure in your intake line. The 2100 can only suck in so much fuel and my guess is that your fuel isn't flowing like it should, heating up while running, and eventually starting to vapor lock (assuming your ignition system is in check). Get the correct filter and mount it with the return nipple on top (yes, it matters.) Run some 1/4" fuel line from your return nipple to the steel return line directly below your master cylinder. Verify correct fuel pressure with a T and a guage. I'd buy the holley red, add a return line, and be done with it.
elboe805 is offline   Reply With Quote Quick reply to this message
Unread 08-21-2011, 12:35 AM   #15
82JeepCJ7
Registered User
1982 CJ7 
 
Join Date: Jun 2010
Location: Marysville, WA
Posts: 4,983
Quote:
Originally Posted by crazy8x4o5 View Post
the last two fuel ups were with fuel that was 10% I try to find a station close with no ethanol. as far as the fuel lines go I've checked them all. My setup doesnt have a return line from the filter
Go to this website and it will tell you where to find it.
http://pure-gas.org/index.jsp?stateprov=GA
__________________
Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
82JeepCJ7 is online now   Reply With Quote Quick reply to this message
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.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

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


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.