Ok, another fuel pump question. I have read, read, and read, but... My 56 customline is getting an electric fuel pump, always had mech. Couple of questions to keep it simple. Should I go inline pump, or not? With a carb setup, do I NEED a return line? Please explain recommended way of doing this. Do I need to start from scratch, or can I use the previous mechanical fuel line for some of this install? (need to check current line size) This will all be for a fairly hot 302/347 engine, 750 holley carb. thx
Tehcnically, all pumps are "in-line." There are pumps external to the fuel tank or in-tank pumps. Some set-ups use both. With a carb you will (obviously) use a fuel pressure regulator. Return line is a great question that I don't know the answer to. F.I. cars almost always have a return but they use much higher pressure pumps. I would guess that having a low pressure electric pump go through a pressure regulator to a carb without a return might be OK as long as the pump had an internal relief or recirc feature.
On a o/t '69 Camaro, I'm running an electric pump. I believe that car has a 3/8" fuel line from the factory and I have no problem with the amount of fuel needed for a warmed over smallblock chevy with a duel feed Holley 650. I 'm using a Holley "blue" pump that comes with a regulator. about $130. Also, not running a return line. You want to mount an electric pump back by the tank, as they are designed to push fuel, not pull it. the regulator goes under the hood and comes w/a mounting bracket. Hope this helps.
In order: Tank. Ball valve - so you can shut the fuel off to service the filter and/or pump. Filter. Regulator. Carb. Holley dead-head (the commonly seen one) is a good regulator for street use and doesn't require a return line. You definitely want a regulator so you can get the fuel pressure down to 5#. The correct pressure takes care of a lot of potential problems in the carb/problems/tuning depts. Your fuel line is probably 5/16" and should be ok. I ran an about 275-300 HP Olds Rocket on 5/16" line in my 50 Ford coupe. Turned 100 mph @13.9 in the quarter, the car weighed perhaps 200# less than your 56. Ran six 2 bbl, three 2 bbl and single 4 bbl at different times on the built Olds. Going up to 3/8" (or #6 in stainless) is good insurance for your good breathing SBF, but I think you'll be ok as is. Be sure and run a relay to the pump. 10 gage wire to feed the relay, 14 gage wire to control the relay, 14 gage wire from relay to pump. Read voltage at the pump after the relay is in. It will probably be at battery voltage or .1 volt lower. (IE: 12.2 volts at the battery with engine off, 12.2 - 12.1 volts at the pump.) A lot of fuel pumps get burned up by running a long 16 gage wire to them. Voltage here may end up in the low 11 volt range which is a big percentage voltage drop. Install a fuel pressure gauge so you can monitor fuel pressure all the way through the gears. Use a mechanical gauge and for sure use an isolater for safety. AutoMeter makes a good combo setup for $$ reasonable. Don't use an inline screw together filter. Some of these are a fire hazard. You can buy a remote oil filter adapter that takes the commonly available (Ford size) Fram PH8a filter. (Although Fram's ain't much of an oil filter and have had bad reviews most places.) Go to a parts house that handles Wix filters and get their fuel filter that's the same size as the Fram PH8a. These filters have a 3/4-16 threaded nipple and there is a smaller Wix filter available that takes (if I remember right) a 5/8-NF nipple. You'll have to have somebody make one of these 3/4-16 to 5/8-NF nipples for you. Another way out is the Fram frame mount filter. Lotta guys run these, they work well and no hassle with obtaining replacement components etc. Clean fuel, good flowing filter, proper pressure, good voltage at the pump should do it....
I prefer a 3/8 to 1/2 inch line. Your ford will probably be either 1/4 or 5/16 stock. A 1/2 inch line would be overkill with the single holley. A return line is cool if you set it up with a monster pump. If you stay under 110 GPH you should be ok without the return line. It all depends on what you use for a regulater, if you are using a regulater with a return port then you want to use a return line. it will need to be the same size as your sulpply line. I do not like in tank pumps, just don't dig running electricity into my tank. But that is entirely up to you. External pumps are easier to set up.
Don't be cheap! Get a good pump I was cheap and learned a lesson in a hurry. Also use a pressure gauge to regulate flow as far as placement I located the pump about 2 feet infront of tank with no return line either.I'm running dual carbs on an inline six with 2.5 # pressure hope this helps you out!
Not that it matters, we are using an S10 blazer tank in my son's 54 Chevy truck with the stock electric TBI pump. We ran a Holley regulator up under the front floor area (access with the battery box lid) and a gauge up at the carb. Run 5# pressure and a return line from the regulator. Works great so far but only about an hour run/drive time.
Thanks for the response. I am thinking about going with the holley blue pump, with regulator. Heard they are a little nosier than others, but when she is purring, I doubt I will hear it when cranked. The holley blue I assume is setup for use with a return line. So, if I dont run a return for my setup, do I just leave the holley pump return feed connection alone, or do i need to cap it off or anything? I see what you mean by technically all being inline. What I was thinking of, is I have heard about some certain pumps being made specifically for use without a return line. So, currently I have the stock fuel line from front to back, when ends right below the engine, and had a rubber hose connected to the mech. pump. When I install the elec. pump in the back near the tank, if I use the existing line, do I just cut the line and tie the pump in, or do I need to just run new line front to back? Also, if I do use the current mech. fuel line, should it be OK to just run steel braided line from the mech. line location, up to the carb, would be about a 2 ft. run or less. For electrical connections, I just bought the rebel wire 20 circuit kit, and got it laid out in the car last night. I "think" its setup to wire in the elec fuel pump with a relay, but will verify that for sure.
Unless you use a positive displacement pump, you won't need a return line with a carb. On most gear type pumps there is enough internal slippage keeping the need for a return line out of the equation.
The high-pressure type external rotary pumps (cylinder-shaped) are meant to feed into a fuel rail, so what the injectors don't use goes back to your tank. If you use one of these you MUST have a pressure regulator in the circuit. But this is like trying to shoot a flea with an elephant gun. The block (or "electronic" ) pumps will run fine (as long as it has enough capacity), and most of the units I have put in struggle to get 6 PSI (they're designed like that). A safety switch of some kind should also be installed so the power to the pump is interrupted if the engine stalls(dead engine+pump running=possible leakage=Kaboom!) I used the ignition sensor relay as fitted to LP gas (Propane in the U.S. I think) setups. It senses ignition pulses , so no pulses=no output (to pump). This is normally wired to the shut-off solenoid on the Propane tank.
It's always good engineering practice to cap off ports that are not being used. Good place for dirt to get in or something to leak out.
My blue pump has no return line port, however, on the regulator, there is one port 'in' and two ports 'out.' You just need to put a cap on one of the out ports of the reg. The instructions with the pump are pretty good, and back up everything being said on here. Also, rubber line with clamps are fine (when 'splicing into your existing hard line), but if you want to do steel braided, check out a company called XRP. They make the standard blue/red fittings, they are nice quality, and cheaper than Earls, Aeroquip or Russell. You can tie up a bunch of $$ in those fittings...believe me!
Why don't you just use a better mechanical fuel pump ? Isn't that the easiest solution ? Why do you want to change to electrical ? If you use a electrical fuel pump I would have a regulator install in it someplace so you don't end up with too much fuel going into the carb and no place to go . I would also use a return line for safety ! FIRE IS BAD !
Run a return line. Todays gasoline is too volatile for the old systems. Without a return line the fuel gets hot in the pump and line, and may cause vapor lock. I know vapor lock does not exist, except it does. In the last few years I have had problems on three cars that I have been running since the 80s without a return line. In all three cases a return line fixed it, when new pumps didn't. I use a tee before the regulator for the return line, solder the fitting shut, and drill it .060. That will maintain plenty of volume.
If you mount the tee with the .060 fitting pointed UP any vapor that may be created will be returned to the tank. Remember you can't push vapor down hill. Vapor only goes up. That is why fuel lines should ALWAYS run slightly up hill.
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