• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

AFB leak down

Stumper

Stumper

FBBO Gold Member
FBBO Gold Member
Local time
2:53 AM
Joined
Oct 28, 2010
Messages
1,538
Reaction score
343
Location
Bandana, NC
Have a Carter 3253s on my 361 bb. Noticed for some time that after the car sits for a week or so, it gets hard to start. Within a few day window it starts easily. I just pulled the carb off after the motor had not been run in a good month or more and there was no fuel in the bowel at all.
Thoughts on where the fuel is going? No sign of external leaks.
 
Evaporating, or your fuel pump check valve has something holding it open...
fuelpumpcheckvalvesm.jpg
 
It must be evaporating. I don't see how it could siphon out the needle valve as the bowl is lower than the inlet port.
You would lose the column of liquid.
 
Safest way to refill the bowls is with a squirt bottle having a rubber tube to connect to the bowl vents.
Squeeze fuel into the vents to fill the bowls and use the accelerator pump to prime the carb.
 
The AFB vent tubes help encourage evaporation in the bowl ps and todays fuels with so many volatiles in them just speeds up the process.
 
I thought about back syphoning through the filter but as noted above the inlet is above the bowl level. I use only the non ethanol 90 octane in the car but Of course it’s still going to evaporate. Its sounding like evaporation may be the problem? This is the first Carter I’ve had, don’t recall running into this with any of the Holley carbs?
 
I have 3 running Holleys and it does happen to them too, I can attest to that. I suspect it may leave a Holley a bit slower because it has sort of a convoluted vent passage through the metering block and out the main body through the single tube, but not sure it’s much different. Also Holleys sometime loose fuel for leaky bowl and accelerator pump gaskets.
 
I dont have any problem with my 850 Holley doing that. I run 92 and 93 pump. Course I also run an electric fuel pump which helps. But it fires up right away unless pretty cold out as I dont wait for the fuel pump to run long I crank it right away. Ron
 
Your heat riser valve isn't stuck shut?
A valley pan with a block off might help.
 
Last edited:
Also float bowls are small and directly above the hot intake. That combination is just asking for evaporation. Worse after a hot soak and today's puppy pee gas sure doesn't help.
 
Darter6 said:
Did that with the last several cars. Most sat for a week or two before use.Put mine on a switch to prime the fuel system,then start the car.
Click to expand...
Something like this?

fuel pump.jpg fuel priming pump.jpg
 
upload_2022-3-29_8-38-15.png

This one blocks off the heat riser port accross the intake.
When I removed the original cast iron intake off my 66 383 there was insulation under the intake.
Don't know how much that would help but it probably doesn't hurt.
 
Darter6 said:
Did that with the last several cars. Most sat for a week or two before use.Put mine on a switch to prime the fuel system,then start the car.
Click to expand...

I did that for years with a BB 66 Corvette I have but didn’t use it very much as I was afraid of its pressure possibly flooding everything. It was a Holley pump for carbs but I suspected it was putting out over 6 psi. But I eventually disconnected it after considering I didn’t have an interruption feature on it in case I was hit hard and the engine killed and the pump continued to run and flood gas out.
 
AR67GTX said:
I did that for years with a BB 66 Corvette I have but didn’t use it very much as I was afraid of its pressure possibly flooding everything. It was a Holley pump for carbs but I suspected it was putting out over 6 psi. But I eventually disconnected it after considering I didn’t have an interruption feature on it in case I was hit hard and the engine killed and the pump continued to run and flood gas out.
Click to expand...
Use a momentary switch for a priming pump. Make sure the circuit is fused.
 
Last edited:
Yes, there are mini pumps. Holley has one called the Mighty Mite $50 Jegs/Summit.
Same pump with many different names such as Mr.Gasket,K&N, ETC.Many pressures including 4-7 psi and 7-10 psi for a few bucks more.
I installed a 1.5 to 4 psi on a 360 4 bbl Cordoba and for a test ran it without the mechanical pump.
Drove it around all day and ran just fine even wide open sprints.
Used as a back up,primer and such. When not running fuel flow runs right thru it without any restriction.
 
The electric primer pump might be the best option. Even after sitting a week I have to run the starter for a good minute to get going and I sure don’t want to have to remove the air cleaner and squirt fuel in all the time.
 
You must log in or register to reply here.

Similar threads

Lamadogg
Fuel Leak Teflon Tape?
Replies
10
Views
656
dadsbee
dadsbee
Stumper
Carter BB fuel pump
Replies
14
Views
1K
RemCharger
RemCharger
C
TQ fuel leak at fuel supply line
2
Replies
24
Views
1K
moparedtn
moparedtn
JJordan1173
Fuel Line Leak
Replies
3
Views
703
WileERobby
WileERobby
Chargerjase
Disaster - Major Fuel Tank Issue
2 3
Replies
50
Views
3K
Chargerjase
Chargerjase
Auto Transport Service
Back
Top