Carb bowl "bleedback?" (1 Viewer)

[Pete_S]

This may be an old hashed over topic, but it's getting a bit frustrating for me. 66 Cruiser w/ 74 driveline.

If my Unit sits for about a week w/o running, the carb bowl goes almost dry, then its.......crankity, crankity. I have a stock set of lines till the filter area. Then I've got NEW lines all the way back to my J**p poly tank under the backend. The return line enters at the top of the tank.

Why does this do this? Is there anything I can do to help alieve this situation. I can't believe that it's a syphon issue as the return doesn't dip "into" the gas in the bowl.

Thanks!

 

[Degnol]

Pete, you might have an internal siphoning problem in the carb. I did have a weak fuelpump and if I parked my cruiser on an uphill, gas would return to the tank. If you have an internal siphoning problem, I'll bet the bowl empties within an hour or so. The other possibility is that you are "boiling" the bowl dry with underhood heat from the exhaust manifold/header. You do have the carb insulator in place, I assume.
.02
Ed

 

[Pete_S]

I have just started to drive this thing as it's a project, near complete, therefore I can't comment on the parking on a hill issue. Typically, it gets run around on the road for an hour or so, then it's parked. The NEXT day, she'll spark right up, noting that the gas is JUST into the site glass. Let it sit for w a week, or so...........then it's crankity, crankity.

The fuel pump may be a bit weak, but don't know how to test it.

This carb insulator thing you speak about............is this a heat shield? There is nothing there, never was since I owned it. Is this something you can educate me about? Can this be fabricated?
Thanks!

 

[Degnol]

It's just a phenolic plastic spacer that goes between the intake and the base of the carb, you've probably got it on there. Your pcv hose may connect there.
PinHead would have a more definitive answer as for where to start eliminating possible causes.
Have you rebuilt the carb?
GL
Ed

 

[IDave]

Is your gas cap vented?

 

[Pin_Head]

If it is not evaporating, chances are that it is siphoning into the carb bore and intake manifold from the idle circuit. The vents in the top cover ("air correction jets") are supposed to prevent this, but will allow it to siphon if they are plugged. Rebuilding the carb is the sure-fire way to stop it. You could also try the down and dirty "Oklahoma" rebuild. Spray the entire inside of the carb with spray cleaner, wait a couple of minutes, start the engine, rev to 2000 and then hand choke it until it almost stalls. Repeat until it stops dripping.

 

[Pete_S]

Thanks for all the replies! BUT
1.) Rebuilt the carb. Acid/carb (water based stuff) dipped it. Everything should be good.

2.) Cap is off the 66. (rigged under the left rear wheel well, fer now) The tank has a fuel filter (vent) hanging off the end of a 1/4" hose,.....for now till I get some type of "system" for a breather.

This actually did this BEFORE I did the engine swap (74 eng into the 66) and the carb rebuild, and the new poly tank!

Now, would I be wasting my time to bring the "return" line up higher than the carb to form a "trap" for the return fuel?