Carburetor loses prime after 8+ hours

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Wrencher

Wrencher

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Hey,

After my car sits for more than 8 hours, i have been having to spray brakekleen in the carb to get it to start. If I work an 8 hour day, it generally starts up when i get off. Sometimes it needs to be primed. When i work a 12 hour day, it wont start. Once running, it runs perfect.

It seems to have started since ive purchased the carb from a member here. I dont think it was doing this with the 1bbl carb so im reluctant to throw a fuel pump at it. Is there something other than the fuel pump that can cause this? what am i missing here??

http://www.forabodiesonly.com/mopar/showthread.php?t=202661
this is the carb in question, and i have it installed on my /6 66 dart
 
You might want to check your fuel lines from the tank to the carb. Today's gasoline is really hard on fuel lines and if you get a crack in the line, the fuel pump might not have enough suction to get going.

My fuel line was cracked at the very top right off the gas tank, couldn't see it laying under the car. Replaced the fuel line, and the fuel pump worked great.

Rod
 
After my car sits for more than 8 hours, i have been having to spray brakekleen in the carb to get it to start

Yikes!!!! Don’t spray chlorinated brake cleaner anywhere it can combust. When burned it becomes deadly chlorine gas, you know the stuff used in WWI, and just a whiff of it will make one very sick instantly.
 
You have not been able to buy the chlorinated "stuff" for some time now. The major content of chlorinated cleaner, "tric" or trichlorethylene, and it is NOT flammable. It is true that chlorinated solvents (if that is what you have) produce poisonous phosgene gas (Can you spell Hitler?)

I guess the "new" stuff is mostly petroleum products, and it will burn.
 
fwiw my car had the same problem when I bought it. I kept a little bottle of gas with me to pour into the carb to reprime it. One day I was caught without the bottle, but I did have a little marvel mystery oil I had been using as a fuel additive. I poured a little of the oil in the carb and started it up. It smoked for a few minutes until the oil burned off, but ever since then the carb keeps its prime.
 
I was having the same problem but it only drained the line carb held gas don't do it unless I'm parked on a hill though
 
Yea the chlorinated stuff has been off the market for some time now. It doesnt take much to get it going. Once the engine hits one good time it seems to pick it right up. Which leads me to believe that the carb is empty but not the line. No black smoke or wet plugs suggests is not running into the engine while sitting.

All of the fuel hose is new. I replaced the sending unit a few month back and i replaced it with the newer fuel injection hose. Not too long ago i replaced the hose and fuel filter near the carb as well.

The choke is not hooked up and probably wont be. The pulloff bolts up perpendicular to the carb and it seems to need to be parallel. Or maybe the pulloff is made differently for the two barrel carb. I dunno. Its not a daily driver so the cold startup issues really wont bother me. I will look in a wrecking yard when i go, and hopefully there will be a slant six there and i can see how its setup.

On the electric fuel pumps, are they regulated or do you have to regulate seperatly? And are you just going with whatever the parts house has?
Thanks
 
would check all fittings and filter go under the car and change the rubber fitting from gas tank there useually wore out cracked and gass flows back down line and u get no sucktion pressure to fill line back up to carb just a thought seen it happen before or a vaccum leak
 
well i replaced the base gasket last week because the old one was causing me pcv problems and the whole cabin wreaked of blowby. i wish i had another carb to try lol.
 
Try a vented gas cap. The old unvented caps will build a small vacuum on the tank when the temp changes. A lot of people rip out the vent line or disconnect the vapor canister so theres no vacuum break. So the tank sucks the fuel out of the bowl cause theres no vacuum break.
 
hmm, that sounds interesting. The car has had the same cap on it forever, but i will go check the vent tube to make sure it isnt restricted...
 
I run about 6" of metal line off my carb and then I run rubber fuel line down to the pump.

My metal line has a 45* bend in it. What I do is position it's ever so slightly bent up in the air. That way even if the fuel does drain back down to the pump, it shouldn't be able to past that bend because it'll have to fight gravity. If you just run your line straight down, then there's no protection against it. This way even if I do have a problem, I'll still have that little bit of fuel sitting in the line up to that 45* bend.
 
ive had a few carburetors percolate before, usually when its hot out, when id shut down my big block i could pop off the air cleaner and see the fuel evaporating out of the vent stacks. a thicker base gasket instead of a thin crappy paper one and the problem disappeared all together. Ive also seen fuel pumps leak into the crankcase or vent hole on the side of the pump body as well, losing prime. so if its "making its own oil" thats a pretty good indicator. if all else fails try a fuel pump check valve, napa used to sell em but discontinued them for some stupid reason. im sure theyre available from other vendors.
 
OK so I just went out to the car and clocked my fuel line off the carb to give it some elevation. That seems like a good idea. I also took the line loose, and turned the engine over. the fuel is in the line, just not the carb.

When i pump the gas, im getting 2 squirts from the jets and then nothing. so the carb is leaking down and im pretty sure i can rule out the fuel pump and backward. Carb it is, right?

Are carters bad about this?
 
I just replaced my base gasket with a thick one. As i said earlier, i HAD been running a thin paper gasket and it was causing my pcv vacuum to bearly pull anything. So the whole cabin would smell of crankcase fumes, which is uninviting to say the least. So i bought a new gasket, which happened to be the 5/8" or so thick, and its been on there for about a week, although i havent driven the car since Tuesday. I think it did it again after the new gasket.

edit; Its doing it now lmao.....oops
 
so should i just run to autozone and pick up an electric fuel pump?
 
Slant 6 Dan has a blog/post on this forum that addresses this issue.
Do some searching and you will find it, i read it about 2 months ago.
 
Those float bowls are very prone to leaks... especially if you are repeatedly pulling it off to make carb adjustments. The tabs that mount the bowl to the carb bend and then it won't seal properly. Then the gas does the rest of the damage to the gasket... it really is silly to have the bowl positioned such that the gasket is always exposed to gas.
 
I had an identical problem on my slant. Turned out to be a weak and dying fuel pump. I replaced it and problem solved.
 
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