304 hot/warm start issue - 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 > 304 hot/warm start issue

Stainless Steel Door Hinge PinsPoly Door Hinge BushingsSave at JeepHut on Smittybilt Soft tops

Reply
Unread 08-27-2014, 09:55 PM   #1
chosen1608
Registered User
1975 CJ5 
 
Join Date: Apr 2010
Location: Gainesville, Fl
Posts: 46
304 hot/warm start issue

I have a 75 CJ5 with a fresh 304 and MC2100 carb. When cold, she starts on first crank. However, once at operating temp, she doesnt want to start. If I give it gas and keep cranking, it will eventually start. At oone point, I had to let her cool down before she would start. Does this sound like a vapor lock issue or a carb issue. Either way, where do I start trouble shooting. I did take the gas cap off, but never heard anything and it didnt seem to make a difference. Thanks for the help!

chosen1608 is offline   Reply With Quote
Unread 08-28-2014, 01:29 AM   #2
grasmo
Registered User
1982 CJ5 
 
Join Date: May 2014
Location: tallahassee, florida
Posts: 152
if a vapor lock issue is suspected, you don't want to keep giving it gas. push pedal to wot, hold, and start. if it starts noticeably easier then you most likely have a boiling issue.
grasmo is offline   Reply With Quote
Unread 08-28-2014, 09:30 AM   #3
CJ5_Fan
Registered User
1980 CJ5 
 
Join Date: Jul 2004
Location: San Jose, Ca
Posts: 751
do you have the fiber carb spacer on the motor or are you running alluminum only? Heat transfer may be an issue. Also, verify your choke position on warm start. Your choke bi-metalic spring may need adjusting.
__________________
1980 CJ5 Renegade with 304 v8

Click HERE to check out my CJ5 restoration project page
CJ5_Fan is offline   Reply With Quote
Unread 08-28-2014, 11:37 AM   #4
certifiablejeep
Bicentennial Nickel
 
certifiablejeep's Avatar
1976 CJ5 
 
Join Date: Aug 2002
Location: Bedford, NH
Posts: 2,258
I put a mean green starter on mine and wrapped it with an "exhaust blanket" and never had an issue... I was having tons of heat from the headers and it wouldn't allow the starter to kick over.

cb
__________________

CertifiableJeep website
'76 ORANGE CJ-5
'76 MAROON CJ-5
'78 SILVER CJ-7
'82 WHITE CJ-8 Build Thread
'83 GREEN UK CJ-7 Build Thread
ORANGE JEEP CLUB #41
SILVER JEEP CLUB #41
SIENNA JEEP CLUB #62
RHD JEEP CLUB #41

NEWJO Member
Forum
certifiablejeep is offline   Reply With Quote
Unread 08-28-2014, 12:30 PM   #5
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 12,754
Does the 75 tank have a return line? AMC went with a dual output gas filter to prevent vapour lock on a hot shutdown. The filter sits level with the return line off the top of it so any vapours produced get blown off the top of the filter back to the tank.

Also the choke setting should be verified as someone mentioned. Even warmed up it needs some choke to start up fast or a few extra pumps of gas are needed.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is offline   Reply With Quote
Unread 08-28-2014, 02:51 PM   #6
bradleybrb
Member
 
bradleybrb's Avatar
1975 CJ5 
 
Join Date: Jan 2013
Location: , MS
Posts: 434
The 75 did not have a fuel return line. I ended up putting one on mine and a wood spacer. They helped it a ton. I was having the same issues that you are having.
bradleybrb is offline   Reply With Quote
Unread 08-28-2014, 08:45 PM   #7
chosen1608
Registered User
1975 CJ5 
 
Join Date: Apr 2010
Location: Gainesville, Fl
Posts: 46
thanks for the responses. My CJ has a return line. I think one of the lines was a little close to the header. I moved that last night and today had no problems starting. I guess Ill see if that solved the problem. Thanks for the help.
chosen1608 is offline   Reply With Quote




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.