Fuel System: Electric Fuel Pump Selection

[JoeHall]

I plan to run a fuel return line on the 63GT, to reduce vapor lock. I have ran return lines in the past, and had problems with the inability of the electric FP to keep up with the additional flow required, under load conditions. I have always used the 35 GPH, 5-7 PSI "cube" electric FP, made by a half dozen companies. There were two versions, the 35GPH being for V8, and a lesser capacity one for smaller motors, which was also OEM on Mazdas back in the day. The cube pump is extremely reliable; I have only had two fail since the mid 1980s, but wanted a FP with more capacity this time.

The 63GT has an electric pump from SI, that was on the car when I bought it, but it does not have capacity for a return line, and bogs immediately. I'd guesstimate it at around 30 GPH.

So, I recently began looking at other FPs, and bought a Holley clone "vane" type that pumps 95 GPH, at 8-10 PSI, but later found those type pumps have a rep for being very unreliable, are not compatible with all gas, and are mostly used in race aps. Further, t is too large to fit anywhere under the Hawk frame, so I probably will have to bite the bullet on it.

I have since found that "Faucet/Purolator" now makes the cube FP in various capacities, and recently bought their largest, at 50 GPH, 12-15 PSI, and "suction draw" of 36 inches. So, with a regulator, that one should fit the bill nicely for the return line. Installation is on the to-do list for this weekend. Will let y'all know how it turns out.

[DEEPNHOCK]

You should not have 'flow' problems if it is plumbed correctly.
There should be a restrictor fitting in the return line that the pump can 'push' against.

Vane type fuel pumps will be noisy and you will hear them all the time, even if rubber isolated.

Are you installing an oil pressure switch and a safety cutoff impact switch?

[bosshoss61]

I thought the motor is what stipulates fuel GPH. I run 355 HP and only need 24 GPH(according to the math) pump. The injectors and or carburetor stipulate pressure...especially on carbureted engines. And from what I've found out vapor lock and GPH have nothing in common. But, lord knows I've been wrong before. Everyone I know tells me I learn by my mistakes----man if that were true I'm a really, really smart guy.

[sweetolbob]

Joe

Agree with Jeff. This is the by-pass fuel pressure regulator I used in the 83 Avanti to feed the 355 SBC with no issues. I bought it so I'd be able to plumb in a return line.

http://www.summitracing.com/parts/hly-12-803bp

It was fed by a Carter pump much like this. http://www.summitracing.com/parts/crt-p4594/overview/ I can get my exact part# for the pump if required.

Bob

[JoeHall]

You should not have 'flow' problems if it is plumbed correctly.
There should be a restrictor fitting in the return line that the pump can 'push' against.

Vane type fuel pumps will be noisy and you will hear them all the time, even if rubber isolated.

Are you installing an oil pressure switch and a safety cutoff impact switch?

Jeff,
I had already installed a .0625" restrictor in the return line for now, in order to keep the car on the road (would barely run without one). But am looking for max flow, in order to keep fresh, cool gas in the supply line, provide a non-restricted return path for circulating fuel during operation, and a non-restricted escape/return path for fuel vapors, to eliminate pressurized fuel-push past the carb inlet needle during heat soak. So I want 1/4" return to the tank, w/o restrictions.
Bob,
If I had not already bought the cube pump, I might try yours. But the cube is smaller, cheaper, and I have used them for years. The pressure regulator was only $31 at FLAPS. For the return provision, I use a filter that has a return nipple, just upstream of the regulator. I like running higher pressure in the lines, because that will also reduce gas vaporization.

Thanks

[SuperHawk]

Joe:

I have installed the Airtex E8012 S electric fuel pump on about 6 of my late model Studebakers. I've installed return lines on 2 or 3 of them as well. The E8012 S will put out about 9 psi pressure, so a regulator is needed. There's a port on the regulator that I buy from Summit that will accept a pressure gage. That way you'll avoid any guesswork when adjusting your pressure down to where you want it. I install the Fram G3499 (I think that's the right part number) fuel filter, that has an outlet properly sized for a return line, just before the pressure regulator under the hood. That way, I have considerable pressure pushing the fuel thru the return line.

Larry

[JoeHall]

Joe:

I have installed the Airtex E8012 S electric fuel pump on about 6 of my late model Studebakers. I've installed return lines on 2 or 3 of them as well. The E8012 S will put out about 9 psi pressure, so a regulator is needed. There's a port on the regulator that I buy from Summit that will accept a pressure gage. That way you'll avoid any guesswork when adjusting your pressure down to where you want it. I install the Fram G3499 (I think that's the right part number) fuel filter, that has an outlet properly sized for a return line, just before the pressure regulator under the hood. That way, I have considerable pressure pushing the fuel thru the return line.

Larry

Hi Larry,
We are definitely on the same sheet. Did you have to run an inline restrictor with that pump?

As mentioned, I am trying for max circulation, in order to transfer as much heat out of the lines and back to the tank as possible. Plus, cooler gas reaching to within 6" from the carb inlet, should cool the carb bowl a little quicker. That's why I was looking for a pump with more capacity. I understand some RVs and trucks used this setup in the 1970s-80s, till EFI came along. My experience when living in the California Desert was that a return line did not cure vapor lock; restart after heat soak still required a bit of cranking, but the engine smoothed out much quicker after restart (vapors cleared from the lines quicker).

I am sure, living in Nevada, you are very familiar with vapor lock
Thanks,
Joe

[SuperHawk]

Joe:

No inline restrictor.

However, a couple of other "tricks" I do use.

1) Depending upon underhood vertical clearance, I'll use either one or two half inch thick phenolic/wood spacers to get the carb up off it's heat source (the intake manifold).

2) Get rid of the factory fuel pump to carb metal line, and go to the FLAPS and get some 5/16 brake line and make yourself a new line. Make your bends in the appropriate places that will result in the new line going almost all the way out to the inner fender apron, then up, then back up and over, attempting to keep it away as much as practical from engine heat sources.

These two things, as well as the return line and healthy electric fuel pump have stopped my vapor lock problems. I might also add that I have had electric pumps fail. Thus, I also retain the stock type mechanical fuel pump on my cars. We'll say it's just for "insurance." I put a switch under the dash for the electric. The Airtex E8012S is what is loosely described as a "blow thru" pump. You can take it in your hand and blow through the fuel inlet and your air will come out the outlet. This is the type of electric pump recommended if you want to retain your mechanical pump. If the electric pump quits working for some reason, the mechanical pump will still be able to draw fuel from the tank right thru the disabled electric pump and thus the mechanical pump will still function as needed.

Larry

[JoeHall]

Joe:

No inline restrictor.

However, a couple of other "tricks" I do use.

1) Depending upon underhood vertical clearance, I'll use either one or two half inch thick phenolic/wood spacers to get the carb up off it's heat source (the intake manifold).

2) Get rid of the factory fuel pump to carb metal line, and go to the FLAPS and get some 5/16 brake line and make yourself a new line. Make your bends in the appropriate places that will result in the new line going almost all the way out to the inner fender apron, then up, then back up and over, attempting to keep it away as much as practical from engine heat sources.

These two things, as well as the return line and healthy electric fuel pump have stopped my vapor lock problems. I might also add that I have had electric pumps fail. Thus, I also retain the stock type mechanical fuel pump on my cars. We'll say it's just for "insurance." I put a switch under the dash for the electric. The Airtex E8012S is what is loosely described as a "blow thru" pump. You can take it in your hand and blow through the fuel inlet and your air will come out the outlet. This is the type of electric pump recommended if you want to retain your mechanical pump. If the electric pump quits working for some reason, the mechanical pump will still be able to draw fuel from the tank right thru the disabled electric pump and thus the mechanical pump will still function as needed.

Larry

Larry,
This is good food for thought. I already had rerouted the line, but used rubber hose, and plan to go to better rubber (FI hose) with the higher PSI pump. I have never ran electric & mechanical FPs together, but it sounds like a good idea. Howeer, I recall one reason for converting to electric years ago was because I could not find a mechanical pump that would hold up for more than six months. My bro-in-law is about to give up, and convert to electric on his 57GH for the same reason nowdays, so I wonder if anything has changed. I hear rumor now and then that there are better mechanical pumps out there, i.e. the 318 Mopar pump, modified for Stude. Which mechanical pump are you using?
Thanks,
Joe

[Corley]

My experience when living in the California Desert was that a return line did not cure vapor lock; restart after heat soak still required a bit of cranking, but the engine smoothed out much quicker after restart (vapors cleared from the lines quicker).

I don't think what you just described ("restart after heat soak still required a bit of cranking...") qualifies as vapor lock. That is just a matter of the fuel in the carb getting too hot upon soak, and a) dumping it'self into the intake, and b) vaporizing / emptying the float bowl. Sure, you may also get a bit of extra fuel bypassing the float valve due to fuel turning to vapor in the line leading from the fuel pump to the carb, but that is not the real problem with that description.

Vapor lock is when the engine can't get fuel to the carb while running, or attempting to start, due to vapor in the fuel lines. (Basically, vapor, or air, will compress, meaning the pump just pushes agaist the air, then relaxes back from it without actually injecting new fuel into the line.) The electric pump and return line both address that problem, getting fuel up to the carb. However, if you don't have at least a tiny bit of restriction in the return line, the fuel will take the path of least resisence and head back to the tank, not through the small float valve and into the carb. It doesn't take much restriction to make a huge difference there, and won't affect your return lines flow much at all.

For the hot soak start problem, (a completely different problem) the insulator block under the carb is about the only help you can give it, but don't expect miracles there, today's fuels vaporize really easily, with not too much temp/soak. SOO you might still see a bit of cranking on a hot start. EFI solves both problems nicely.

JMHO

[SuperHawk]

Hi Again Joe:

I have used the mopar pump. Without modification, I had the actuator arm break off while driving. On another mopar pump, the actuator arm has not broken off. I've not done the arm-bending modification, although I have been tempted. I guess I am reluctant to want to heat the arm and bend it because I am afraid of weakening the metal.

As for Studebaker style mechanical pumps, a Carter boxed pump is now available through normal Studebaker parts vendors. It has a metal tag on it denoting manufacturer's P/N 4227, just as the old and unworthy Airtex pumps did. However, the newer one now available is greatly improved. The actuator arm pivot shaft is no longer just driven into the pump body, free to move back and forth, and create oil leaks. The new pivot pin is peened on one end and has a captive washer on the other end. They seem to work far better than the old Airtex pumps.

Larry

[jnormanh]

I plan to run a fuel return line on the 63GT, to reduce vapor lock. I have ran return lines in the past, and had problems with the inability of the electric FP to keep up with the additional flow required, under load conditions. I have always used the 35 GPH, 5-7 PSI "cube" electric FP, made by a half dozen companies. There were two versions, the 35GPH being for V8, and a lesser capacity one for smaller motors, which was also OEM on Mazdas back in the day. The cube pump is extremely reliable; I have only had two fail since the mid 1980s, but wanted a FP with more capacity this time.

The 63GT has an electric pump from SI, that was on the car when I bought it, but it does not have capacity for a return line, and bogs immediately. I'd guesstimate it at around 30 GPH.

So, I recently began looking at other FPs, and bought a Holley clone "vane" type that pumps 95 GPH, at 8-10 PSI, but later found those type pumps have a rep for being very unreliable, are not compatible with all gas, and are mostly used in race aps. Further, t is too large to fit anywhere under the Hawk frame, so I probably will have to bite the bullet on it.

I have since found that "Faucet/Purolator" now makes the cube FP in various capacities, and recently bought their largest, at 50 GPH, 12-15 PSI, and "suction draw" of 36 inches. So, with a regulator, that one should fit the bill nicely for the return line. Installation is on the to-do list for this weekend. Will let y'all know how it turns out.

I'd stick with the Purolator cube type. They're reliable and not very expensive. I got 20 years out of my first one, and the second is now 15 years old. They're cheap enough that I carry a spare. Restrict the return line to keep the pressure up. 1/16" should be fine, in fact with a 50 GPH pump you can go up to 3/32", even 1/8". If hot start due to vaporization is a problem, remember that you've got an electric pump, so switch ign on, and wait a few seconds for it to deliver cooler fuel. 50 GPH is way more than your car can use, so you'll be returning plenty of fuel. Plumb the return line in close to the carb.

As for the Holleys - I recently met a friend for breakfast, and his year old Holley failed just as he pulled in. I loaned him my spare Purolator, and he ran it until our next meeting. He'd trashed the Holley for a Purolator of his own.

[JoeHall]

Jeff,
I agree on the cube type FP. My experience has been same as yours. I was glad to discover they now make them with larger capacity. I am gonna try the larger cube on the GT and see how it works. If needed, I can later add a Mopar 318 pump, as Larry has successfully. Larry lives in Nevada, so his experiences with vapor lock weigh in heavily

Corley,
Over the years, I have came to use the term, "vapor lock" to refer to anything having to do with heat vaporizing fuel to the point that it causes problems with running the motor. That includes lines, fuel pump, carb, etc.. Usually those problems are tethered together; they often accompany each other; help one, and you often help the others. Just incorrect terminology on my part, due mainly to laziness and ignorance

Sounds like we both share similar experiences with EFI; it is the only CURE I have found to date for vapor lock on a Stude. All other remedies simply alleviate, to some extent. Even cumulatively, the other remedies do not come close to curing the problem, as EFI does.

Joe

[SScopelli]

I went with a precision electric fuel pump. It is a solenoid type pump that you can mount 24" above the tank, but I placed it in front of the right front spring mount so it is in line with the fuel line.. Mounted on a ruber shock mount there is no real noise unless the tank is empty.. With fuel running through it, it is fairly quite. If you are standing by the right rear wheel, you will hear it.

This pump puts out 9psi at 24 GPH..

OK.. I know all of your calculations and all, but at 80 MPH I'm getting 20 MPG, I used up only 4 gallons in that hour! So what happen to the other 20 gallons this fuel pump, pumped?



On the engine side I used a pressure regulator and the fuel filter with a return line port for the "R" engine..



I attached a fuel pressure gauge to the return line by the tank, and with the engine running, I set it to set the pressure to 5.5 psi since I'm running the Carter AFB. Any more than that and you WILL flood your Carter..



Here is the wire diagram I used to hook it up. I use ground as the trigger for the relay because that is what is coming from the oil pressure switch. If you hook 12v to the OPS, the idiot light will not work..

So when there is OP, the switch is ground, but while you crank the engine you want the pump to run. So use the Start pin on your ignition switch to energize another relay that will switch the ground to the fuel pump relay..



It uses two relays, an inertia switch in the trunk and a Oil pressure switch that has the oil light @ 0 psi fuel switch at 3 psi





As for lack of fuel to the Carb, I found that as a limit to the capacity of my tank!

[JoeHall]

You should not have 'flow' problems if it is plumbed correctly.
There should be a restrictor fitting in the return line that the pump can 'push' against.

Vane type fuel pumps will be noisy and you will hear them all the time, even if rubber isolated.

Are you installing an oil pressure switch and a safety cutoff impact switch?

"Correctly" is subjective. For me, correct is when my stated goals are reached. Said goals are now reached with the install of the above pump, which now returns about 10 GPH back to the tank via the 1/4" return line. There is no restrictor, that would limit flow to less than 1 GPH. Now, within 5 seconds of turning the key on, the fuel supply line is completely purged with fresh, cool gas, all the way to the filter, within 6" of the carb. Any vapor problems remaining will be limited to the last 6" of line, and the carb bowl. Even those will clear up quicker with fresh, cool gas coming in almost instantly.

I drove the car over 20 miles this AM, and no problems with fuel starvation, or with excess pressure at the carb inlet valve. Hot restarts will be evaluated when opportunities present.