6 Pack losing prime overnight

[lyndondb]

My 440 six pack loses fuel prime overnight. Takes 30 to 40 seconds grinding the starter to pick the fuel back up. Starts all day fine afterward. But overnite same thing again.
Anyone got any ideas.

 

[HEMI-ITIS]

Next time before you start,check the accelerator pump squirt,does some fuel out when you move the throttle ??

 

[69 GTX]

Also check your rubber connector hose between the hard lines at the tank. Had a car once that drove me crazy just like yours. The fuel pump could pull hard enough with the air leak till it fired.

 

[HEMI-ITIS]

Even if the fuel line was leaking down,it would not empty the fuel bowls......

 

[Yatzee]

My 440 six pack loses fuel prime overnight. Takes 30 to 40 seconds grinding the starter to pick the fuel back up. Starts all day fine afterward. But overnite same thing again.
Anyone got any ideas.

You're probably losing fuel at the carbs from evaporation or leakage due to deteriation of a rubber part like an o-ring etc. Carbs don't usually "back siphon" thru the fuel line as the float drops because the inlet is usually high on the body. The only way to confirm if the bodies are leaking down would be to remove one carb top. Don't know what fuel grade you're using but ethanol based gas is a bitch on rubber parts in carbs. Don't discount any component before the carbs like fuel pump, partially blocked lines or a dirty filter sock in the tank. The easiest (possibly) fix would be a small quiet primer pump (like a Carter) if the type of fuel is the issue. Good luck!

 

[Daves69]

Smell your oil if you suspect it is leaking down. Also check that you are not running the float too shallow in the bowl.

Additionally, make sure your choke is set properly.

 

[68 HEMI GTS]

Center carb could have a small leak into the pv chamber and be draining if that's whats going empty. might need some new gaskets. not exactly sure what loosing prime means, could relate to a lot of different issues.

 

[PurpleBeeper]

Next time before you start,check the accelerator pump squirt,does some fuel out when you move the throttle ??

I'm going to try this one myself.

Someone on the other identical post said it could be "heat soak" boiling the fuel out of the center carb... another possibility for sure IMO.

 

[idrivemopar]

That was me that mentioned heat soak on the other post, because my 340 with thermoquad does the same thing if it sits a day or more, all the fuel is gone out of the floats, and its not a leak, I have checked that, but it does get quite hot under the hood, even with a plastic spacer, I think just the ambient air temp is enough to evaporate that fuel since the thermoquad has a vent tube open to the atmosphere and the purge line to the charcoal canister.

 

[lewtot184]

my bet is evaporation. also, if the carbs are getting really hot, I've seen fuel boil over and out the boosters. this can create two issues; fuel level will be very low in the bowls on start-up and fuel can pond on the intakes valves (if closed) and create a flooding condition on start-up. this modern gas can be a pain in the fanny for carbed engines. the alcohol makes matters worse.

 

[beanhead]

I had this problem due to shot accel. pump diaphragms, gas would dribble out overnight but would be evaporated every time I looked for signs of leaks. I finally stuck some paper towel under the carb ends and the next day, even though they were dry they smelled like gas. after I rebuilt the carb problem was gone

 

[MoparHonda]

I had the gas line at the tank problem years ago with a '70 Dodge.

 

[lyndondb]

Thanks to everyone for the advice.

Also check your rubber connector hose between the hard lines at the tank. Had a car once that drove me crazy just like yours. The fuel pump could pull hard enough with the air leak till it fired.

Don't understand what you are saying. The fuel pump could pull hard enough? Check the line for leaks in fuel air>?

 

[PurpleBeeper]

Thanks to everyone for the advice.

Don't understand what you are saying. The fuel pump could pull hard enough? Check the line for leaks in fuel air>?

I think what 69GTX is saying is this...... IF you have a small leak, cracked hose, pinhole in the metal fuel sender nipple, loose hose clamp, etc back by the tank.....THEN the car might run just fine. The fuel pump (especially a high performance one) might just be sucking in a little air from that pinhole leak, but still get plenty of fuel up to the engine while you're driving. It won't even smell like gas or anything. BUT, when you shut the engine off, the fuel can dribble out that little pinhole and/or just allow the fuel in the lines to flow back into the tank....so the fuel line is empty when you fire it up in the morning.

Now that I think about it, IF you had a pinhole leak in your fuel system somewhere, it could NOT empty the carburetor....just the fuel line. If you had a fuel pressure gage, you would see it reading low for a few seconds when you fired the engine up.

 

[HEMI-ITIS]

In order to pressure test the fuel system,The fuel line would need to be removed from the tank and carb feed before the split.
Then pressurize the line with not more than 10 lbs.You would have plug and secure one side so the air pressure does blow the plug off.On the tank side,,if it is rubber,a small bolt that would fit inside the hose with a hose clamp would insure it would not blow out,then pressurize the carb side.Might have to fill the line with liquid if you don't hear an air leak under pressure.

 

[PP1RT]

Even if the line drains back into the tank wouldn't there be enough fuel in the center carb to at least fire up when he first hits the key? Sounds like a gas boiling problem at shutdown maybe? Leaving the bowl empty?

 

[440beep]

Look at the intake manifold, driver side, under the center carb. There's a deep cavity in the intake manifold, is it full of fuel? If so, feel under the accel pump and is it damp with fuel? Mine used to leak there. Damn accel pump gaskets.

 

[miller]

Question. Have the carbs floats, needles, and seats been looked at?

 

[lyndondb]

Thanks for all the advice. I am still working on this. I will post results.