1990 wrangler hard start (carb) - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today

Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 01-13-2010, 08:53 PM   #1
Join Date: Jan 2010
Posts: 1
1990 wrangler hard start (carb)

I have a 1990 Wrangler 4.2L (weber carb) that takes about 4 cranks to start with cold engine. I replaced the fuel pump (mechanical) and fuel filter, plugs, wires. It seems like the fuel does not reach the carb?? I pump the gas 3x before starting....still no go. Once it starts up it runs great right away. If it sits for a day, it goes back to 4 long cranks again. Any ideas??
sps is offline   Quote
Old 01-13-2010, 09:19 PM   #2

WF Supporting Member
Fweaky's Avatar
Join Date: Aug 2009
Location: Central Virginia
Posts: 2,226
Choke working?

Nothing is foolproof to a sufficiently talented fool.
Fweaky is offline   Quote
Old 01-13-2010, 09:41 PM   #3
scott howard's Avatar
Join Date: Dec 2009
Location: wichita falls texas
Posts: 1,035
Have you done the nutter bypass yet if not that is your first thing to do.
Then set the timing at 8 degree's.
Make sure your choke is working and if it is your carb is most likely a little lean
and a lean mixture will make for hard cold starts.
If you have no stumbling or rough running once warm i would say you dont have vacuum leaks.
and with the weber carb you only need 3.5 pounds of fuel pressure so i assume you have a regulator for that,

But first do the bypass , set timing , new plugs, adjust air mixture and that should do it.

give me a call if you need more help

scott howard
scott howard is offline   Quote
Old 12-10-2014, 10:51 AM   #4
Join Date: Dec 2014
Posts: 1
Just bought my daughter a 1990 Islander I6 engine. It starts fine in warm weather but anything under 35F it cranks & cranks then starts after 5 minutes.
I'm not savy with stuff like this and hoping its an easy fix. Any suggestions?
JD082570 is offline   Quote
Old 12-10-2014, 01:38 PM   #5
kik's Avatar
Join Date: Dec 2008
Posts: 7,779
What happens is when it sits the fuel drains out of the bowl and it takes a few cranks for the fuel pump to fill it. Then it will start. It's a common issue. If my 89 4.2 sits for a day it's fine. If it sits 2 or more it has to crank more and then it will start. Once it starts it goes right on a high idle and the carb functions properly. The carb worked perfect for a few years after a rebuild and then the seals slowly allowed fuel to leak. It happens with all of those carbs, some leak more and some less. The only way to fix it is to re-seal the carb./ rebuild it or you can replace it if it progressively gets worse.
kik is offline   Quote
Old 12-10-2014, 01:50 PM   #6
kik's Avatar
Join Date: Dec 2008
Posts: 7,779
Originally Posted by JD082570 View Post
Just bought my daughter a 1990 Islander I6 engine. It starts fine in warm weather but anything under 35F it cranks & cranks then starts after 5 minutes.
I'm not savy with stuff like this and hoping its an easy fix. Any suggestions?
In this case most likely your choke isn't working. Loosen, but don't remove the cap on the auto choke and see if you have a broken spring. If not try adjusting it to 1 notch rich and see if that works. If not, you could have an issue that's internal to the carb which is causing the choke not to set. Check the mechanism and see if it will manually set, meaning the carb plate closes when cold. It should close but not all the way. If it does it might only need an adjustment. If it doesn't close at all, the internal auto choke mechanism might have failed. You can always add an electronic choke. They're not expensive. Or, you can get a manual choke kit, attach it to the carb. and control it manually which you can hook up under the dash.
kik is offline   Quote
Old 12-10-2014, 05:44 PM   #7
Fabrokoner's Avatar
Join Date: Apr 2013
Location: Plymouth, CT
Posts: 384
Also the fuel filter placement can cause hard starting issues. The 4.2's fuel filter has a return line this should be on top. Above the port that goes to your carb. Also the whole filter should should be mounted above the fuel inlet on the carb. That is why the 4.2 has those hard fuel lines.

If either if these are not right, fuel from the float bowl could be returning down the return line. Then when you go to start the engine you have to fill the float bowl which you can only do by cranking the engine since it's a mechanical pump. Hence the long cranking after it sits.
Fabrokoner is offline   Quote
Old 12-10-2014, 06:44 PM   #8
Supporting Member

WF Supporting Member
::WF Moderator::
Tom95YJ's Avatar
Join Date: Sep 2013
Location: SLC, Utah
Posts: 2,539
I have no issues with mine I started it for the first time in a week. Pump the gas 1 time and she fires right up.

(Weber 38 carb/ Crt Hei ) I also have a engine block heater I plug in. And it's garage kept

1989 YJ : Lifted/ Armored Tom95YJ's The Smurf Build Thread
1999 XJ : Lifted/Locked/Armored
Tom95YJ is offline   Quote

Thread Tools

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 Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
1990 wrangler FS in Chico, CA ccpanel Classifieds Archive 1 07-11-2009 02:13 PM
1990 Wrangler - fuel pump & sending unit 93Gr YJ Tech Forum 15 05-11-2009 08:47 AM
Should I buy the 1990 Jeep Wrangler?? steveshra YJ General Discussion Forum 13 06-15-2007 07:05 AM
1990 jeep wrangler problem mbehr WF New Member Check In 14 02-21-2007 10:59 PM
1999 Jeep Wrangler cranks and no start troymach1one TJ Tech Forum 1 07-10-2006 10:02 AM

Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 02:04 PM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC