Vapor lock? Bad ignition part? Or . . .?

Discussion topics on Willys Overland M series vehicles
Post Reply
jbjeeps
Active Member
Active Member
Posts: 179
Joined: Sat Jun 12, 2010 6:00 pm
Location: Idaho

Vapor lock? Bad ignition part? Or . . .?

Post by jbjeeps »

I've been using the A1 to run errands lately.

Twice, on hot afternoons, 90+, it failed to start after shutting it off and going into a store for 20-30 mins.

Both times I opened the hood, let it sit for 30 minutes or so, and it started right up.

Next time I take it out during the heat of the day I'm going to leave the hood open when I shut it off and see if that makes a difference.
1953 M38A1 (His)
1963 CJ5 w/Tuxedo Park Mk III (Hers)

See you at the Old Jeep Rendezvous in Ashton, Idaho 9:00 am - Noon on the first Saturday after July 4th. All pre-1970 Jeep vehicles, military or civilian, stock or modified welcome.
User avatar
Ryan_Miller
Site Administrator
Site Administrator
Posts: 1682
Joined: Sat Apr 02, 2005 6:00 pm
Location: Kansas

Post by Ryan_Miller »

How close are your fuel lines to the exhaust manifolds - this was more of an issue with the M38 than the M38A1, but it does bear some consideration.
Ryan Miller
MVPA # 22010
User avatar
oilleaker1
Jeep Enthusiast
Jeep Enthusiast
Posts: 973
Joined: Wed May 13, 2009 6:00 pm
Location: South Dakota

Post by oilleaker1 »

It's rebelling and wants to go back into the mountains. You have to go back to the basics when it fails and check for fuel, spark etc. If the base of the carb shows wet gas residue, it's flooding due to a overfull float bowl. You may need to clean the carb out and re-assemble. Primary seat /float could be leaking by. Gas tank is venting OK, etc. Gas would be the first check, but my money is on cleaning the carb. You obviously have had a recent change in something after all the drives and videos. If it was electric, it wouldn't run well after running a while. Heat would be coil , which is the opposite here. If you don't have gas at the carb until alot of cranking, you may have a loose fuel line or air leak, or fuel pump acting up. Keep us informed on what you find. Forewarned is forearmed, especially with British. I found on my Brit cars that have sat until their turn each year that the primary inlet bango feed where the fuel enters the SU's, the needle and seat gum up and stick. A tap with the wood handled screwdriver suddenly allows fuel to enter the floats and wallah Vroom! :lol: John
jbjeeps
Active Member
Active Member
Posts: 179
Joined: Sat Jun 12, 2010 6:00 pm
Location: Idaho

Post by jbjeeps »

How close is fuel line? The line that leaves the pump and goes to carb exits at back of pump and goes between pump and engine, about 3 inches below the exhaust manifold at the closest point. It's an aftermarket pump, no vacumn chamber.

I'm guessing fuel too John. Thanks for the good checklist of possibles. I probably need to add "rebuild carb" to this winter's work list.

Wants to go back to the mountains? Roger that! We're planning a trip up into the Boise National Forest for Saturday, October 15. I'll be posting trip info on the forum tomorrow. Check it out! Join us!
1953 M38A1 (His)
1963 CJ5 w/Tuxedo Park Mk III (Hers)

See you at the Old Jeep Rendezvous in Ashton, Idaho 9:00 am - Noon on the first Saturday after July 4th. All pre-1970 Jeep vehicles, military or civilian, stock or modified welcome.
Post Reply