1977 Jeep CJ Carb float bowl draining.

Hey Group,
Just a nagging little problem with an old Jeep CJ that I've got laying around. This Jeep has the original 258 straight 6 with a Carter YF (I
think, but won't swear that's correct) carb.
Everything starts and runs great, but if she has been sitting for about 3 days or more, it takes quite a lot of cranking before she fires up. My best guess is that the float bowl is draining during this time and it just takes a bit to pump more fuel up into the carb. If she's only been sitting for a day or so, she fires right up seemingly on the first revolution.
I have not noticed any leaks or anything that would indicate the fuel is dripping out, so the question is... where can it be going? Or am I not even thinking of what the real problem may be?
--
Tom O

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Check the accelerator pump and choke first.
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TomO wrote:

Some carburetor castings are a little porous and so the fuel may "bleed" out all over the carb rather than in one concentrated drip. Also, 3 days is enough time for a lot of fuel evaporation to take place, so it may just be the nature of the beast.
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Clean and properly adjust the automatic choke. HTH, s
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The most usual cause for that is the gas filter being installed upside down. The filter has two outlets, the center one goes to the carb and the 'top' one goes to the return line. If this return line isn't at the top, gas will siphon back to the gas tank when it sits causing your 'dry' starts.
The second cause is a pinhole leak on the suction side of the pump. Usually these happen at the flex lines or where the clamps hold the steel line to the frame. It will just show as a stain at first because it is a suction line, but it is enough to let air in when it sits.
Third and the most unusual is a failure in the pump's back flow valve. You can check this by having it running, then shut it down and unhook the inlet to the pump to see if gas drains out.
Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id !15147590 (More Off Road album links at bottom of the view page)
TomO wrote:

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Mike Romain wrote:

Thanks Mike, You nailed it. I had two of the three problems you listed.
I'd never heard that the fuel filter needs to be installed with the return line above the carb feed. Makes perfect sense now that I think about it though. I had to rotate mine 180 degrees.
The rubber line that is the feed to the fuel pump had many cracks in it. As a matter o' fact, it appeared to be an original because the clamp on the fuel line side was one of those crimped on types. I replaced that chunk of fuel line.
A 24 hour test had her start right up, now she's sitting for a few days more to see what happens.
--
TomO

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TomO wrote:

You are welcome.
I too had the filter issue, but was reading my owners manual and there it was, the directions on the positioning.
I also believe this is one reason some folks cry that their 258 runs out of gas on a steep climb. I go up sand pit walls and have never had a gas supply stall.
Mike
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Mike Romain wrote:

I always thought that was from tipping the float bowl at a high angle. Now I'll have to go climb a hill and see if that works better as well. This old Jeep suffered from that problem for many, many years. On mine, it seemed that I'd have to be bouncing as well as climbing to get that stall.
It wouldn't actually stall, more of a severe stutter in my case anyway.
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TomO wrote:

I rebuild my carb every few years just before emissions usually and always have my float at the book spec for height.
Mike
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