CJ5 258 sputtering 3/4+ throttle - JeepForum.com

LinkBack Thread Tools
post #1 of 13 Old 07-25-2013, 09:38 PM Thread Starter
Registered User
1978 CJ5 
Join Date: Jul 2013
Location: Clermont
Posts: 3
CJ5 258 sputtering 3/4+ throttle

Hey, I'm new to the forum and am a new owner of a 1978 CJ5 with the I6 and 4 speed transmission. My grandfather fully restored this thing (he claims $25k invested) 10 years ago and placed it in a garage of an old house of his. The roof collapsed and it has been getting rained on for I don't know how long. I pulled it out a couple of weeks ago and have been working on it. We have struck a deal and now I'm the owner. It is running and it didn't take too much to get it to run (new starter, new battery, freed up some linkages) and it ran on 10+ year old gas. I have driven it probably 200 miles since I've been working on it and it runs great. However, it has a sputter when you really get on it. I found a small pinhole in the fuel line between the fuel pump and fuel filter, fixed that and it has helped some, but it still has that sputter. It is difficult to get up to speed acting this way. I know it can be a variety of issues and I have scoured this forum looking for similar cases, but none of them are really like the issues I'm having. The jeep idles great and runs great up until you give it 3/4 throttle. From there to WOT it has a sputter. It still accelerates (slowly on level ground) but it is sputtering out the exhaust. It almost seems like it is starving for fuel, but I replaced the fuel filter yesterday. Has anyone experienced this kind of behavior before? Oh, I forgot to mention, that after I fixed the pinhole in the fuel line, it took it 30 minutes to start acting like this, the first 30 minutes were perfect, then it started sputtering. It's almost like it waited until it was nice and hot to start acting up. Anyone have experience with this problem before? Any help is appreciated!

Jdtench is offline  
Sponsored Links
post #2 of 13 Old 07-25-2013, 10:00 PM
Registered User
1986 CJ7 
Join Date: Mar 2007
Location: Jacksonville, Oregon
Posts: 2,309
First.....Welcome to the Jeep Forum!! Tons of stuff here for your CJ5. Great looking rig!!

The issue you are describing could be caused by any number of things. A distributor that is not advancing properly, old spark plugs or partially fouled, excessive exhaust system back pressure, gummed up carb, debris in the fuel tank that is covering the fuel outlet, etc.

You are going to need to continue to eliminate items one by one. The biggest issue you have is a rig that has not been operated in ten years.

Good Luck..............

'86 CJ7, 258, Carter BBD, Nutter'ed, TeamRush'ed, T-18, Twin Sticked Dana 300, D30 Frt-Pwr Lok L/S-4.10, AMC 20 Rear-Mosers-Detroit Locker-4.10, 2.5 BDS Lift, 1" Body Lift, 33" Wild Country M/Ts, Black Spoke wheels

'45 CJ2A, L134 Go Devil, T-90 Tranny, Warn O/D, T-18 T-Case, Dana 25 Frt, Dana 41 Rear, 531st CJ made

My 401 build: http://www.jeepforum.com/forum/f8/tr...build-1338277/
Trapshooter is offline  
post #3 of 13 Old 07-25-2013, 10:45 PM
Registered User
1976 CJ5 
Join Date: Sep 2010
Location: Stephens City
Posts: 147
Nice ride! Im far from an expert, but it sounds like a simple vacuum leak. Possibly as simple as the hose for your vacuum advance being cracked.
Hope its something simple and obvious. I hope mine looks that good soon.
dison001 is offline  
post #4 of 13 Old 07-26-2013, 03:07 PM Thread Starter
Registered User
1978 CJ5 
Join Date: Jul 2013
Location: Clermont
Posts: 3
Ok, the sputtering has all but stopped. I looked at the vacuum advance and the distributor and cleaned all of it really well. I don't think it was advancing enough (not enough movement from gunk being in there). Now, it has a new symptom. I will be driving along fine and all of a sudden it'll bog down. If I let off the throttle it'll return to normal for a brief second then bog down again. If I keep the throttle so it stays bogged down, it'll backfire. It almost seems like it is not getting enough fuel. I guess I need to really inspect the fuel system (carburetor and fuel tank) It runs so well otherwise.
Jdtench is offline  
post #5 of 13 Old 07-26-2013, 03:55 PM
Registered User
1972 CJ5 
Join Date: Mar 2013
Location: westtown
Posts: 104
I had a similar probably and it drove me crazy trying to figure it out and it ended up being a bad fuel pump.
Jack718 is offline  
post #6 of 13 Old 07-26-2013, 04:00 PM
Registered User
1985 CJ7 
Join Date: Jul 2010
Location: The Mojave Desert - Palmdale, Ca. U.S.A.
Posts: 6,389
Points ign?
What the rpm when it stumbles?
3/4 pedal, under load or cruise'n.
Can you 'sneak' up on it, or is it every time?
LumpyGrits is offline  
post #7 of 13 Old 07-26-2013, 04:19 PM
Registered User
1977 CJ7 
Join Date: Mar 2011
Posts: 3,865
He should have the Motorcraft Electronic Ignition if it's stock.

I'd rather be lost on the trails than found at home!

Phoenix Rising- A Flame Off Restoration? http://www.jeepforum.com/forum/f8/ph...ation-1807257/
WindKnot is offline  
post #8 of 13 Old 07-26-2013, 04:37 PM
Registered User
2006 LJ Wrangler 
Join Date: Jan 2004
Posts: 625
I'd rebuild a carb thats been sitting that long. Odds are the pump diaphragm is bad. If you can accelerate but only if you do it very slowly and gradually (as opposed to mashing the pedal half way down, etc.) that is your must likely culprit of the poor acceleration.

'94 YJ - SBC/AX15/231, SOA, 8.8, 34" swampers
'06 LJ Rubicon - 31" ATs, OME 2.5", belly-up skid, other junk
'75 CJ5 - 232/T14/D20, 'glass tub w/ 2" BL, otherwise stock
jdarg is offline  
post #9 of 13 Old 07-26-2013, 07:14 PM
Registered User
1985 CJ7 
Join Date: Jul 2010
Location: The Mojave Desert - Palmdale, Ca. U.S.A.
Posts: 6,389
SWAG+ gummed up gas mixed with water.
Replace fuel and fuel filter.
LumpyGrits is offline  
post #10 of 13 Old 07-26-2013, 07:29 PM
Web Wheeler
86cj74.2L's Avatar
2004 WJ 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,279
The more you flogged it the more dirt got sucked into the main jets possibly.

Do you have a two barrel or a 1 barrel carb?

Like mentioned earlier sitting that long its a good idea to take everything apart, making sure nothing is growing in the fuel bowl.
86cj74.2L is offline  
post #11 of 13 Old 07-26-2013, 09:38 PM Thread Starter
Registered User
1978 CJ5 
Join Date: Jul 2013
Location: Clermont
Posts: 3
Ok, I had patched a pinhole in the fuel line going from the fuel pump to the fuel filter, but never could quite get it to quit leaking. So, I ordered a replacement and got it in the mail today. Installed it and it solved the problem! I do plan on going through the whole system soon, but glad to know that that issue has been resolved. Thank you guys for your help, this place is great! I should probably mention for future reference that I did pull the distributor cap and rotated the center just a little and heard a pop. Sounded like something got dislodged and then allowed it to advance further. This got rid of the sputtering.
Jdtench is offline  
post #12 of 13 Old 07-26-2013, 10:14 PM
Registered User
1981 CJ7 
Join Date: Jul 2009
Location: Bali
Posts: 5,389
You may be sucking air as the hoses above the fuel tank rot and split. They start allowing air in which gets worse over time and you will hear the engine spluttering flat out or going uphill, the pump is sucking air in and the level in the float bowl in the carb starts to fall.

If you let the engine idle for a minute and then it is fine for 20-30 seconds before it starts splutterring it is almost certainly the level in the float bowl sinking.

As it has been sitting you may find some benefit in dropping the tank, cleaning it out and checking all the hoses at the back. The fuel pump diaphragm could also have rotted but the pumps are cheap.

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
BagusJeep is offline  
post #13 of 13 Old 07-27-2013, 12:29 AM
Registered User
1984 CJ7 
Join Date: Sep 2010
Location: Hazleton
Posts: 199
That's a pretty little jeep. It's great that you got it (mostly) running good.
Just a thought. Now might be the time to go through the fuel, ignition, vacuum, brake line and lube systems (all soft and fluid systems) and check, clean, replace as needed, or as a precaution. Then you can monitor all systems, including the hard mechanicals. Like has been said before in this thread, 10 years is a long time to sit, and petrochemicals, their hoses, seals and filters don't all really sit around to well (once they're out of the box and out of environmentally-controlled warehouses.) Some of the old electricals could be getting up in corrosion as well. BTW - as other(s) have mentioned - there's improvements (i.e. - Nutter) here on the forum that usually work a lot better than the old systems that the OEM installed (and are a LOT more "KISS" than the OEM systems as well - important when PM'ing).

Good luck
Jeep-N-0311 is offline  

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