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  #16 (permalink)  
Old 08-13-2014, 09:05 PM
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use bigger diameter line. I use 1/2 inch. return line is good

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Old 08-13-2014, 09:12 PM
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Common problem on alot of vehicles is vapor lock usually caused by a faulty vented gas cap or blocked and/or poor functioning e-vap system. The vented gas cap is designed to vent small amounts of air into the car gas tank line. The vented gas cap has a one-way release valve that is pressure-activated. When the pressure reaches a certain point (defined by so many pounds per square inch) the valve opens by a very small amount, relieving some of the pressure. In this case, the pressure is formed on the outside of the tank, due to the vacuum formed from the displacement of fuel on the inside. After the pressure inside the line equalizes, the pressure valve closes. The valve is set to balance the pressure with the surrounding atmosphere. Air is allowed in, but no fumes are allowed out of the gas cap, because of environmental concerns.
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Old 08-13-2014, 09:28 PM
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pumpin

You can run both pumps together if you have a fuel pressure reg between the two of them.
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Old 08-13-2014, 09:44 PM
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Quote:
Originally Posted by mud.man.rj View Post
You can run both pumps together if you have a fuel pressure reg between the two of them.
what will happen if I run the electric pump to the mechanical pump? I was told the Mechanical pump will act as a regulator
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Old 08-13-2014, 10:04 PM
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pumps..

Why hope for that and put all the load of an electric pump on the mechanical, what if it starts to leak thru one of the 2 diaphrams, one leaks out and one leaks into the engine into the oil, not worth trusting the secondary pump, run a pr reg, then forget about it.
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Old 08-13-2014, 10:29 PM
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The Carter P4070 electric pump does the same job and does not need a regulator.
With it you can keep the mech pump or remove the mech pump for more consistant performance in hot weather.

On the mech pump the rubber joint connecting hose between the frame and pump, on the pump feed side is probabily collapsing/kinking under heat.

The P4070 needs no regulator and easily feeds this motor thru a 3/8" fuel line.

The Carter P4600HP pump will also feed this motor by itself, with a fuel pressure regulator at the carb.
You can remove the mech pump, either way.

If you get creative and correctly fabricate a rubber isolation mount these carter electric pumps they are pretty quiet.
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Old 08-13-2014, 11:14 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
The Carter P4070 electric pump does the same job and does not need a regulator.
With it you can keep the mech pump or remove the mech pump for more consistant performance in hot weather.

On the mech pump the rubber joint connecting hose between the frame and pump, on the pump feed side is probabily collapsing/kinking under heat.

The P4070 needs no regulator and easily feeds this motor thru a 3/8" fuel line.

The Carter P4600HP pump will also feed this motor by itself, with a fuel pressure regulator at the carb.
You can remove the mech pump, either way.

If you get creative and correctly fabricate a rubber isolation mount these carter electric pumps they are pretty quiet.
I made sure that the rubber hose has no sharp bends and is wrapped in DEI Heat Sheaths, you think this Carter P4600HP electric fuel pump will feed my BBC 439, its only a street car Carter P4600HP and redline set at 6000 RPM

the pump came with some rubber bushings and installation kit to install, I had to buy separately was a Summit Racing Fuel Pump Relays #SUM-890023
I have read some stories lately of guy's forgetting to shut there electric pumps off once the car is shut down and destroying the engine from hydro lock, will Wiring the Relay to an ignition source prevent from forgetting that the pump is left on?
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Old 08-13-2014, 11:23 PM
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fuel problem

If I was going to use an electric fuel pump I would run a 100 micron filter leaving the tank and before the pump. See attachment for diagram of fuel system.
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Old 08-14-2014, 12:04 AM
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Quote:
Originally Posted by cdminter59 View Post
If I was going to use an electric fuel pump I would run a 100 micron filter leaving the tank and before the pump. See attachment for diagram of fuel system.
so do I have to run a return line? I have a wix 10 micron filter would that work? and also a brand new sock on the pick up in the tank
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Old 08-14-2014, 12:31 AM
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Originally Posted by 1981zapper View Post
so do I have to run a return line? I have a wix 10 micron filter would that work? and also a brand new sock on the pick up in the tank
Why don't you flow test the system on the car and find out the flow volume for
yourself.
A good $10 paper element 3/8" in out common fuel filter is fine.

Two 110" holley needle seats are the same as a .156" flow test orifice (5/32")

the Carter electric pumps do not need a return line. The P4070 does not even need a regulator.
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Old 08-14-2014, 12:36 AM
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Quote:
Originally Posted by F-BIRD'88 View Post
Why don't you flow test the system on the car and find out the flow volume for
yourself.
A good $10 paper element 3/8" in out common fuel filter is fine.

Two 110" holley needle seats are the same as a .156" flow test orifice (5/32")

the Carter electric pumps do not need a return line. The P4070 does not even need a regulator.
I appreciate all the help you guys have been giving me its frustrating figuring out this fuel issue, I have a brand new drivetrain and can't drive the car anywhere on a hot day

How can I do a flow test?

I'm running a Edelbrock 800CFM AVS carb

ok good to know about the return line
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Old 08-14-2014, 12:42 AM
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That little rubber hose does not need heat wrap. But the mech pump can use a heat shield gasket
The little hose is supposed to be a reinforcied hose that will not kink or collapse from heat.
If you want the pump to be quiet fabricate your own custom rubber mount hanger and hang it from the frame of the car. When it is hung on a good rubber isolation mount it does not transfer noise to the chassis.
Much like a good rubber Muffler hanger. Use good short rubber hose to connect the pump to the fuel line also.
(to isolate noise transfer) They are very quiet when you bother to rubber mount correctly.
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Old 08-14-2014, 12:44 AM
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The edelbrock carb is fine. But needs a regulator when using a pump with 8psi. P4600HP.
Cut the pressure to 5.5psi. The Carter P4070 does not need a regulator atr all.
The text book eddy float height setting is a good start. You can +/- it a bit to find the best.
8psi is too much pressure 5.5psi is just right.

Eddy carbs like a wood carb heat spacer under the carb. Split divided if dual plane manifold.
manifold heat riser should be blocked or restricted to reg carb plenum heat.
Wide open is too hot.
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Old 08-14-2014, 12:50 AM
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Quote:
Originally Posted by F-BIRD'88 View Post
The edelbrock carb is fine. But needs a regulator when using a pump with 8psi. P4600HP.
Cut the pressure to 5.5psi. The Carter P4070 does not need a regulator atr all.
The text book eddy float height setting is a good start. You can +/- it a bit to find the best.
8psi is too much pressure 5.5psi is just right.

Eddy carbs like a wood carb heat spacer under the carb. Split divided if dual plane manifold.
since I have already have the carter P4600HP, I will use it, I do have a holley regulator


Is it possible that since I'm going to run the electric pump close to the tank and get rid of the Mechanical pump that the pressure will drop once the fuel gets to the carb and I will not need a regulator?
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Old 08-14-2014, 01:14 AM
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flow it on the car, into a big wine bottle that you marked for 1 US quart.
time how many seconds to fill 1 US quart into the bottle. Flow thru a test orrifice that has equal
area of the combined area of the two needle seats.
AREA not diameter.

EG a .156" test orifice (5/32") is = to two .110" needle seats. same AREA.

GPH flow is .... timed secs for 1 quart ...X 4 ='s time to flow 1 gallon. (in seconds)

60/f (seconds to flow 1 gallon) ='s flow test (1 US gallon) time in minutes.

Divide 60 by this number, to get flow in GPH ( gallons per hour)


Just fill a suitable wine bottle with 1 US quart of water and mark the level with masking tape.

flow the fuel thru the system at the operating test voltage, thru the fuel filter and thru the test orrifice, into the bottle. Time with a stop watch. Average say 4 tests .

Now you know the real system flow and how much horse power it will support.
Horsepower divided by 12 ='s GPH flow required at WOT.

EG 500hp needs 41.66 GPH ( US)


No it will not drop at idle. From just he distance. And you do not want restriction to flow. Yes you need a regulator with the P4600HP pump.
If you don;t want a regulator change to the P4070 carter pump.
use the holley pressure regulator and set with a good gauge or get the Carter P4070 pump.
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