69 gtx 426 with a fuel leak back

[raymondsclassic]

Hey guys my names Raymond
I have a little garage and boy I’ve got one aggravating me I need some help with!
A customer picked up a 69 gtx 426 four speed car with literally 20,000 miles (I pulled the factory rear brake shoes off!)
Okay so the entire fuel system has been replaced tank,lines,fuel pump and all! I rebuilt the Carter afbs and replaced some of the rubber lines and insulated the metal lines around the engine because someone decided it didn’t need protection down the frame rail by the exhaust manifold
Anyway actual problem is its loosing prime if it sets for a few days and I’m tired of scratching my head here hope maybe some of yall might hit on some angles I haven’t thought of
If you start it every day or two it does great no problem but if it sits say 5 days you have to prime it.
So any of you have any suggestions I’d love to hear em! Thanks yall in advance

 

[moparedtn]

Nothing unusual about that at all or specific to that car, for that matter.
As long as the car otherwise performs properly once you get it started, there's nothing "wrong".
There's been several threads on here about this subject - feel free to use the "Search" feature
to find them, but in general...
it's the fuel they sell these days, simply put.

Some have gone to the extent of installing a small electric pump inline just to prime the carb
on cold starts to combat it, others have used other methods - and some of us just know it's going
to happen on a given Saturday and crank away until fuel gets pulled back up into the carb.

 

[Bighouse]

All that cranking gets the oil flowing before it kicks off- that’s how I look at it.

 

[AR67GTX]

AFB carb fuel bowls are well vented and modern gas is highly volatile. It will be half evaporated within 3 or 4 days in most circumstances. I always prime mine with a ketchup bottle through the vent tubes and dribble a little down the throat. Or you can first spin the motor without touching the gas pedal for 2 or 3, 5 second spins to fill the bowls and then pump the throttle 2 or 3 times and spin it to start.

 

[Beekeeper]

Once the fuel evaporates to a low enough level to drop the float and dropping the needle off the seat the fuel will drain back to the tank.

 

[68BabyBlue]

Ethanol free gas will help reduce the problem, but won't eliminate it completely.

 

[#41]

Sounds normal to me. Every carb'd Mopar I own requires spinning the engine to build up fuel and several pumps to prime the engine if it's been sitting for more than a couple of days. The longer they sit, the more is needed. If the choke is off, an adjustment may improve it a little. In the days of fuel injection and computerized ignition we have forgotten what it used to be like.

 

[raymondsclassic]

Once the fuel evaporates to a low enough level to drop the float and dropping the needle off the seat the fuel will drain back to the tank.

I never really thought about that that’s the kind of answer I was looking for thank you

 

[raymondsclassic]

Ethanol free gas will help reduce the problem, but won't eliminate it completely.

We’re already running 92 non-ethanol customer has a 1,000 gallon tank at his shop and adds octane boost every few fill ups

 

[68BabyBlue]

We’re already running 92 non-ethanol customer has a 1,000 gallon tank at his shop and adds octane boost every few fill ups

Your experience is consistent with what I had with my stock Hemi GTX, running comparable fuel. If it sat for more than a few days, I'd prime the rear carb, after a couple cranks to get the oil moving. With 10% ethanol, it would starve for fuel after sitting for an afternoon.

 

[raymondsclassic]

Nothing unusual about that at all or specific to that car, for that matter.
As long as the car otherwise performs properly once you get it started, there's nothing "wrong".
There's been several threads on here about this subject - feel free to use the "Search" feature
to find them, but in general...
it's the fuel they sell these days, simply put.

Some have gone to the extent of installing a small electric pump inline just to prime the carb
on cold starts to combat it, others have used other methods - and some of us just know it's going
to happen on a given Saturday and crank away until fuel gets pulled back up into the carb.

Well see it’s only this particular car out of a 12 car collection. He has 3 other mopars two 340 six-pack cars and 440 super commando superbird plus other brands of big block four speed cars I won’t mention on here lol
The superbird does do it if it sets for about two weeks but it picks back up fairly quick.
Like I said in a another reply we are running 91 or 92 octane non ethanol with an occasional bottle of octane boost but what beekeeper said makes perfect sense because I’ve got almost every car down to a one pump cold start but the two pumps this car takes after sitting overnight would be more than enough air in the line to drain it back to if not past the pump!
Sorry sir I’m have more realization of this as I am trying to respond to you lol you guys are great I appreciate your input

 

[RJRENTON]

Once the fuel evaporates to a low enough level to drop the float and dropping the needle off the seat the fuel will drain back to the tank.

No....it won't.... because of the discharge check valve in the fuel pump prevents reverse flow....UNLESS the vehicle has the vapor separator system, then residual pressure drops to zero when the engine shuts down.
BOB RENTON

 

[dadsbee]

Ya because every old fuel pump is "crap free" with nothing holding the check valve diaphrams open Bob...

 

[not so famous bob]

Hey guys my names Raymond
I have a little garage and boy I’ve got one aggravating me I need some help with!
A customer picked up a 69 gtx 426 four speed car with literally 20,000 miles (I pulled the factory rear brake shoes off!)
Okay so the entire fuel system has been replaced tank,lines,fuel pump and all! I rebuilt the Carter afbs and replaced some of the rubber lines and insulated the metal lines around the engine because someone decided it didn’t need protection down the frame rail by the exhaust manifold
Anyway actual problem is its loosing prime if it sets for a few days and I’m tired of scratching my head here hope maybe some of yall might hit on some angles I haven’t thought of
If you start it every day or two it does great no problem but if it sits say 5 days you have to prime it.
So any of you have any suggestions I’d love to hear em! Thanks yall in advance

I didn't read any of the posts , but /
electric fuel pump , or a one way check valve ...

 

[Sixpactogo]

I believe your fuel pump is the culprit here. My 60 Dart with a 318 4bbl would lose it's prime after a day of rest where I had to crank and pump the throttle for maybe 20-30 seconds before it would fire. I replaced the fuel pump and now it starts immediately even after sitting a couple days. If a week or longer, it will crank longer before firing but much sooner than before.

 

[RJRENTON]

Ya because every old fuel pump is "crap free" with nothing holding the check valve diaphrams open Bob...

The fuel pumps check valves are metallic valve dics; the flexible pumping diagram is the pumping member. Perhaps you could benefit of a review of fuel pump construction is in order....don't know what crap free means....
BOB RENTON

 

[toolmanmike]

Hey guys my names Raymond
I have a little garage and boy I’ve got one aggravating me I need some help with!
A customer picked up a 69 gtx 426 four speed car with literally 20,000 miles (I pulled the factory rear brake shoes off!)
Okay so the entire fuel system has been replaced tank,lines,fuel pump and all! I rebuilt the Carter afbs and replaced some of the rubber lines and insulated the metal lines around the engine because someone decided it didn’t need protection down the frame rail by the exhaust manifold
Anyway actual problem is its loosing prime if it sets for a few days and I’m tired of scratching my head here hope maybe some of yall might hit on some angles I haven’t thought of
If you start it every day or two it does great no problem but if it sits say 5 days you have to prime it.
So any of you have any suggestions I’d love to hear em! Thanks yall in advance

If all is well with the fuel system and carbs, it could be normal with today's puppy pee gas we have now days. Regular gas with no alcohol helps but it can still occur. Th fuel evaporates out of thee float bowls in a few days tim. Many fellas have installed a small electric priming pump to fill the carbs before starting. A momentary pushbutton switch powers th pump. Here's a thread about it. Electric priming pump for fuel evaporation issues.

 

[dadsbee]

The fuel pumps check valves are metallic valve dics; the flexible pumping diagram is the pumping member. Perhaps you could benefit of a review of fuel pump construction is in order....don't know what crap free means....
BOB RENTON

LOL Bob, I'd show you pictures of mine stuck open with a piece of **** stuck in the check valve, but it's not worth my time for you.

 

[1962MAX]

Hey guys my names Raymond
I have a little garage and boy I’ve got one aggravating me I need some help with!
A customer picked up a 69 gtx 426 four speed car with literally 20,000 miles (I pulled the factory rear brake shoes off!)
Okay so the entire fuel system has been replaced tank,lines,fuel pump and all! I rebuilt the Carter afbs and replaced some of the rubber lines and insulated the metal lines around the engine because someone decided it didn’t need protection down the frame rail by the exhaust manifold
Anyway actual problem is its loosing prime if it sets for a few days and I’m tired of scratching my head here hope maybe some of yall might hit on some angles I haven’t thought of
If you start it every day or two it does great no problem but if it sits say 5 days you have to prime it.
So any of you have any suggestions I’d love to hear em! Thanks yall in advance

 

[1962MAX]

I have a 67' GTX HEMI and it did that since day one. And when I say Day One that was since November 1966. Life's too short...Don't worry about it.