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Is it possible to drain a carb dry under acceleration?

As kiwi said up above, same thing happened to me and it turns out it was the fuel pump pushrod. If you have another pump, wouldn't hurt to try it out, but I'd say while you're in there, pull the pushrod and give it a look.
 
moparedtn said:
You know, you bring up a point I've wondered about myself since I installed the Carter "hemi" fuel pump that Mancini sells:
http://www.manciniracing.com/cabheen5psis.html
I always wondered why the inlet and outlet on these is only 1/4" NPT.

For example, the Edelbrock pump (that looks just like the old Carter design) has 3/8" NPT inlet and outlet, yet is rated for 10gph less than the Carter is?
http://www.manciniracing.com/edmeperpmse6.html

I do have an almost new "regular" fuel pump sitting on the shelf I could try, but its' inlet and outlet sizes aren't so great, either - and it's not rated nearly as high on flow rate.

As an aside, this thing seems to drain the fuel bowls in the carb after just sitting a day or two also. Wonder if that's from evaporation or the pumps' check valve
not holding?
Could it be related?
Click to expand...
The carb loosing fuel from sitting is typically from evaporating, had that problem too. I just bought a phenolic spacer to insulate the carb, problem solved.
I don't think to many carbs will just drain back to the tank even if there wasn't a check valve. The seat is usually bringing fuel in above the fuel level making it impossible for the fuel to just drain back.
 
moparcrazy said:
Really hard to say from all the info given BUT!, what size is your Fuel Line (if stock? TOO Small), Sending Unit, Stock ? TOO Small!! what is the GPM on the Pump???

FYI i run All 7/16 Lines, AKA -8,
Better up grade ! running Lean could Toast your Motor !!
Ill post pics
Click to expand...
Fuel line is all 3/8" - what the factory used on all 440 and hemi cars.
So is the sending unit.
Pump GPM is 120gph, considerably more than stock.

Keep in mind, this is no race car. Pretty damn stock, really.
 
HT413 said:
As kiwi said up above, same thing happened to me and it turns out it was the fuel pump pushrod. If you have another pump, wouldn't hurt to try it out, but I'd say while you're in there, pull the pushrod and give it a look.
Click to expand...
Ok, but as I just posted in #37 above, the pushrod has been replaced. Thanks.
 
747mopar said:
The carb loosing fuel from sitting is typically from evaporating, had that problem too. I just bought a phenolic spacer to insulate the carb, problem solved.
I don't think to many carbs will just drain back to the tank even if there wasn't a check valve. The seat is usually bringing fuel in above the fuel level making it impossible for the fuel to just drain back.
Click to expand...
I have a 3/4" composite spacer on there now; it was necessary for the secondary linkage to clear the factory intake.
I know these Edelbrocks are infamous for "losing" their fuel, however.
Thanks.
 
First, pull your sending unit and check your pick-up. Is the filter clogged and is if is sitting in the right place. Check sending unit operation or fill tank prior to test. Second, enlarge the openings in the pump if they go down to a 1/4 inch. Lastly, I know you have stated the fuel system is new, but pressure or vacuum test your system from Carb to Fuel tank. Easiest thing to do, pull the hose at the tank and plug it real good, remove your fuel line from the carb and apply vacuum with a gauge and let it sit, if it holds great, if not start tracing back from Pump to tank...
 
Please don't take this the wrong way, but new does not mean it is working as it should... Start from the back and work forward..
 
I Think Fuel Pump!!, a 650 carb starving for gas ? and fuel gauge dropping like that with 3/8 line ??
 
Derwud said:
Please don't take this the wrong way, but new does not mean it is working as it should... Start from the back and work forward..
Click to expand...
Oh no, no worries at all. Just giving some background.
I'll remove the pump and blow some compressed air back to the tank to make sure the new everything is still wide open.
I'll check the new pushrod at this time as well.
Finally, the only thing left is the pump itself. The brand new, expensive mofo pump that has been rock solid at 6.5 psi ....until now. :)
 
moparcrazy said:
I Think Fuel Pump!!, a 650 carb starving for gas ? and fuel gauge dropping like that with 3/8 line ??
Click to expand...
Yep. Probably. All I can make sense of, too.
I'll get into it and see what's what soon, thanks.
 
Hey y'all. Guess what the warranty is on this Carter fuel pump?
*smirk*
 
moparedtn said:
Oh no, no worries at all. Just giving some background.
I'll remove the pump and blow some compressed air back to the tank to make sure the new everything is still wide open.
I'll check the new pushrod at this time as well.
Finally, the only thing left is the pump itself. The brand new, expensive mofo pump that has been rock solid at 6.5 psi ....until now. :)
Click to expand...

The reason for vacuum testing is, guess what the fuel system is under, before the the pump.. I had a hose that had a split in on the top side of the hose out of sight. I happened to have my car on a rack trying to diag the same kind of problem and I touched the hose and it made a sucking sound, BINGO.. Vacuum would be easier.
 
moparedtn-After reading all this,Im still thinking needle&essay on the floats. It's been a long time for me but I don't remember a bigger seat assy. for them as for the holleys. I still think ur draining the bowls. Or your pickup sock is collapsing?
 
oldbee said:
moparedtn-After reading all this,Im still thinking needle&essay on the floats. It's been a long time for me but I don't remember a bigger seat assy. for them as for the holleys. I still think ur draining the bowls. Or your pickup sock is collapsing?
Click to expand...
Oh, no doubt I'm draining the bowls, since that's the final entry point for fuel before getting shot down the barrels of the carb - and the jetting seems to be ok, in the ballpark anyways.
This is actually a very good point!
Holleys have dual inlets for fuel, after all, right?
Well, there's only the one inlet for this Edelbrock AVS. It can be converted to run dual inlets, however...

but here's the thing. The factory got by fine with a single feed to the carb, right?
 
Interesting little item this morning.
I am going to work on the car this weekend, but I was in the garage for something else this morning, so I figured what the heck, start the car and see what the gauge says.
Now, keep in mind the other day when she starved out, it read like 4psi when I pulled in the garage @ idle.
Today on a cold start and warmup? 6.5psi, like it always has.
:wtf:
Ok, it ain't like gas has viscosity that changes like oil does with temperature.
I hadn't touched a dang thing since the other day, either.
'Splain that one, Lucy?
 
Just means either your sucking some air, have a restriction or the pump is giving in.
 
Well, I've been over the whole damn thing again. I couldn't find any leaks.

However, when I took the line loose from the suction side of the pump, I expected to take a bath - it had pretty much done that back when I replaced all the fuel lines earlier this year, especially in the rear parts.
This time - nothing. Not a drop.
Keep in mind, I ran it this morning.
It appears the fuel line is draining itself back to the tank after shutdown, meaning the pump has to get a fresh pull every time the car is started.

I take it this isn't normal?
 
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