Carter 6V electric fuel pump

[caddy60]

I have a carter 6v electric fuel pump installed in my 38 Caddy. Can anyone tell me how I would hook up a flow regulator or pressure regulator, piping & electrical. The bellows style I had before would shut off once the carb was satisfied. The rotoray style run forever! My intention is to only use the electric pump for starting when the car has sat for long periods of time or on occasion whenit appears it is vapour locking.  The concern I have is if I forget to turn off the electric pump I take the chance of loading up the carb if I am only ideling.

Your feed back would be greatly appreciated

Bruce Watson
tralee@telus.net

[Classic]

Several Thoughts:  1.  Hopefully this is a pump of recent vintage.  Older pumps will fail due to ethanol in modern fuels.  2.  If it is a 1 wire pump, make sure it is a positive ground version.  If a 2 wire pump, ground the positive wire.  3.  Like you, I use my pump for priming and possible vapor lock.  Therefore, I use a push button switch for my pump, not a toggle switch.  That way there is never a chance of leaving it on.  4.  If only intermittently using the pump for priming and possible vapor lock, a pressure regulator is not needed.

[DWR46]

The Pressure Regulator you want is available from Summit Racing Equipment online or at 800-230-3030. It is Mr. Gasket #9710 at $26.95. It is adjustable from 1-5 psi. Set it at 2 psi and install it "downstream" from the Carter electric pump. 2 psi is enough to fill the carb, but not too much to force the needle off its seat and flood the carburetor. i have this setup on all my classics.

[John Washburn CLC 1067 Sadly deceased.]

Folks,

I have to respectfully disagree. The requirement for the 1938 Cadillac is 4 to 4 1/2 psi, so setting at 2 psi is incorrect, it might run OK, but not necessarily under load or at altitude.

Second, the cheap regulators are OK, but ponder using what the hot rod guys use. They are expensive but don't fail as some of these ones listed have done occasionally. I use a Mallory regulator and generally buy a used one on eBay (all aluminum)...

But as always, what do I know.

The Johnny

[Glen]

If this is an auxiliary pump then the 2 PSI setting is OK, the mechanical pump will provide the necessary pressure. 

My only concern with this arraignment is with the aux pump not pumping and a pressure regulator in the line they will provide a drag on the fuel and lower the pressure in the fuel line, increasing the likelihood of vapor lock. 

Glen

[Bill Ingler #7799]

I live in Phoenix, the Valley of the Sun as well as the vapor lock. Even before I moved to Phoenix I was using the pulse type pump. Then the additives started to eat away at the pulse pump. I installed a Carter vain type pump and filter near the tank. I now was getting more vapor lock with the Carter than with my old pulse pump. As Glen explained, with the aux pump off and the Carter being a vain type pump, that makes the engine fuel pump work harder to pull the fuel from the tank to the engine pump. Now throw in a regulator,fuel filter and the engine pump is working harder and harder, the pressure is getting lower to overcome the drag through the vain pump, regulator and filter. Lower pressure with increase in heat and soon you have a vapor lock. Most of the vapor locks develop in the engine driven pump.

I have never used a regulator on my cars even with a Carter. I think the rating on the Carter is max of 6.2 and the engine pump is someplace between 4-6lbs. I have never had a flooded engine because of too much pressure from using a Carter. If I am climbing out of Phoenix towards Flagstaff which is at 7,000, I leave the Carter on all the way with no problems

I use the Carter on my 47 with the following modification. This idea was from Buck Varnon in MI. Using a one way check valve which requires very little vacuum to open has solved most of my vapor locks. Picture below is how the set up looks on my 47. Several more here in Phoenix are using the same set up.    Bill Ingler

[John Washburn CLC 1067 Sadly deceased.]

Bill,

Elegant. i ran a line from the electric fuel pump to the fitting on the manual one, with a one way valve, to do the same. Your solution is lovely and so much easier.

John Washburn

[DWR46]

At the risk of beating a "dead horse", there is NO pressure on the intake side of the mechanical fuel pump, only vacuum. The mechanical pump creates a vacuum in the line to the tank, thus drawing fuel from the tank to the pump. At the pump, the fuel is pressurized and pumped to the carburetor. As long as the mechanical pump is able to create adequate vacuum, through the electric pump, one-way valve or pressure regulator, everything will be fine.
Many electric pumps are designed to have fuel drawn through them, including the Carter, Facet and Autoflux. Most pressure Regulators have very little restriction to fuel drawn through them. You can easily check by using your mouth to suck air through the regulator. There is very little restriction.
Most vapor lock conditions are not related to the vacuum created by the mechanical pump, but rather by the fuel boiling downstream between the pump and the carburetor. Usually the vapor lock is caused by excessive heat in either the mechanical pump, the fuel line itself or the carburetor float bowl.  An electric pump will move cooler fresh fuel through the line and force the vapors into the carburetor, followed by the fresh cooler fuel. Another major reason for the prevalence of vapor lock in carbureted cars today is the current fuel composition, but that is another whole subject.

[DWR46]

On the subject of Pressure Regulators, my business is vintage race cars. We have used various pressure regulators in our cars, primarily, Holley, Mr. Gasket and a few Mallory. We have had failures in all three makes over a 40 year period, but nothing abnormal. The Mr. Gasket unit has the advantage of being easily adjustable without requiring a fuel pressure gauge to set the pressure. I have found this unit to be quite accurate when checked against a master gauge. I also do not want to in any way argue with Mr. Washburn, but Iwould be very careful purchasing a USED fuel pressure regulator. Fire is the most feared thing in a race car, or a special classic Cadillac. The fuel system is not where we choose to place used parts.

[markl]

I have enjoyed reading through this discussion, and also find the set-up that Bill depicted an elegant solution as to how the electric fuel pump should be incorporated.  However, before anyone installs one w/ any intention other than using it strictly as a priming device, I think we need to have a little discussion about one major drawback to having an electric fuel pump; that is, in the event of a collision, if the ignition switch is not shut off, the thing could keep pumping if a fuel line is broken.

I think this has been covered in another previous thread, but I'd like to hear what someone like Mr. Ridgley has to say about it.  I know that some sort of inertial switch is mandated on SCCA race cars, and appears on the only modern cars I happen to wrench on (Alfas).  I would think that a switch such as this (Normally Closed) would not be a problem to incorporate into a 6 volt system.  But that is only speculation on my part.  Any experience out there with installing this decidedly modern component into one of our 30's era cars?

Mark Lowery, CLC #25216

[DWR46]

Markl: You have asked a very good question. As to electric "booster" pumps for classic/antique cars. I prefer to activate them with a separate switch, and only use the pump to fill the carb prior to cold starts and if needed under high temperature conditions. On some 1950' and 1960's muscle cars, we install electric pumps that run all the time in conjuction with the mechanical pump. These are usually wired thru the ignition switch. As to race cars, the issue with pumps running after a accident is why NASCAR mandates mechanical pumps only. Many vintage race cars used electrical pumps originally, and we still use them often. No vintage sanctioning body to my knowledge requires an inertial shutoff switch. Is it potentially dangerous, yes, but one of the first things a race driver is taught, is to kill all the switches (if he can) as soon as the crash is over. That is also why all vintage race cars must have a master electrical cutoff switch easily accessible to rescue workers from outside the car.

[John Washburn CLC 1067 Sadly deceased.]

Mark,

You make an excellent point and that is why on all new manufactured electric fuel pumps the instructions shows one how to hook it to the oil pressure switch. No oil pressure no juice to the electric fuel pump. So as always is up to the individucal to decide what safety precautions to take.

This brings me to the posting by DWR46. He did not ruffle my feathers, I agree new is better than used, but the Mallory pump I use is pretty bullet proof. Costs around $100.00 new. Picture is attached, I believe you can get new parts for these and rebuild them. I just never had much luck with the Mr Gasket, Carter, or others who made the cheaper models. That may be past history since they may have fixed the problem of ethonal destroying the rubber.

John Washburn

[CEC #20099]

I always wire my electric pumps with a red or yellow pilot light that is visible to the driver when the pump switch is ON. As far as using momentary, spring loaded switches for safety, try getting a 39 Buick , overheating & vapor locking, home , holding a toggle switch, for 75 miles. That is dumb.

The Check valve idea is one I have wanted to try. It must have a very low cracking pressure. McMaster-Carr lists one.

I have a Carter 6V VANE Pump on my 53 Dodge, for priming purposes. The pump is strong, noisy, & draws a lot of current. It also should be mounted low alongside the tank, as it is NOT SELF PRIMING, & can destroy itself running dry.

For 12V vehicles, the AC DELCO MARINE pump seems to survive any fuel, is self priming, & lasts forever.

c chleboun #20099

[Glen]

Dyke,

I understand what you are saying but that discussion can go on forever.  (The “No such thing as suction” discussion)  I can tell you stories about trying to pump fluids in a vacuum.  Can’t be done. 

There are two ways to measure pressure PSIG (gauge) and PSI Absolute.  A standard pressure gauge measures pressure in relation to the ambient pressure.  Absolute pressure is measured in relation to a perfect vacuum.  So in one sense there is always pressure in a fuel line, even with the engine off the pressure in the line will be ambient (atmospheric).  The boiling point of gas will be dependent on absolute pressure.  The information I find on the internet says the lighter elements in gas boil out at 100 F degrees at sea level. If you are on Trail Ridge Road (11,000 ft + above sea level) or even in Denver (5,000 ft +) the boiling point is much lower than that.  Now add in the pulse of lower pressure caused by the intake stroke of the mechanical pump and the pressure goes even lower along with the boiling point. 
   
While I can’t say that vapor lock never happens on the output side of the mechanical pump it is less likely than on the intake side.  If vapor does occur in the output side I would think the pump would just push it through the carb and there would be little disruption in the flow, unless the boiling is continuous. If the vapor occurs in the intake line it expands as the pump tries to pull it in or if it does get into the pump the vapor just expands and compresses as the pump works resulting in no liquid being transferred. 

The addition of an auxiliary pump only needs to increase the absolute pressure a couple of PSI to raise the boiling pressure significantly. 

Unfortunately I can not find a pressure to boiling point chart for gasoline to be more specific. 

[caddy60]

I would like to thank everyone for their replys. I feel with the information I have I can resolve my problem. Thanks very much.

Bruce Watson

[Fred Zwicker #23106]

I am looking at all of this information and am wondering if several electric fuel pumps that I have installed are OK, or will they result in later problems?

I have installed an electric fuel pump in the main fuel line on several of my cars.  These were installed near the gas tank, as heard that electric fuel pumps push better than pull.  I also installed a fuel line filter between the gas tank and the electric pump.  I did NOT install a pressure regulator in any of my installations, as my pumps were rated at low PSI and always seemed to work well without any problems.

Several of my cars use this setup without the original (non-electric) fuel pump and all are working well.

Several other of my cars use this setup with the standard original (non-electric) fuel pump.  Since these cars have a working non-electric fuel pump, I use the electric pump only for priming the carburetor after car sits for some time.  Once primed and engine has started, I shut off the electric fuel pump and the original (non-electric) fuel pump does its job.

In both of the above examples, the electric fuel pump is wired through the ignition switch to an in-line fuse, and then to an auxiliary under the dash lighted switch, which feeds current to the electric fuel pump near the gas tank.  None have a relay, although I always use heavy wire to the fuel pump.  I have used this setup in both 6 volt and 12 volt cars.

None have an oil pressure shutoff switch, which I agree should be added for safety, but every time something else is added, there is more chance for a malfunction.

I have always wondered if the non-electric fuel pump is able to easily pump fuel through the electric fuel pump when the electric fuel pump is turned off?  It seems as if there would be some resistance that might cause vapor lock or other issues? The neat installation (using a check valve) shown by Bill Ingler in his earlier post seems to be a logical solution to any resistance within the fuel line when an electric fuel pump is installed in the line.

Fred

[CEC #20099]

Fred Zwicker: CEC here. I have Terry`s Oxblood Maroon 39-61 Conv Cpe.
I have done some pressure drop tests using a 39 Buick 248 engine and various fuel pumps. I started this because I got into a disagreement with the owner of Antique A C, about his fuel pumps. He insisted that me attempting to pull fuel thru a non-running elec fuel pump was a cardinal sin, & I must use a bypass. The car was a bone stock, orig 32000 mile Buick. I did a bunch of pressure & vacuum tests, and found less than 1/2 psi pressure drop, at the carb. His mechanical pump was still 2 psi short of spec. I am running 4 or 5 cars , same way as you, with no problems.

The real problem is today`s fuels. 2.5 psi is NOT ENOUGH to keep them from boiling, regardless of the original published specs.
If you want to email me, we can go into details.
Oxblood Maroon is beautiful !!!   CEC #20099

[caddy60]

Fred,

That is a very interesting test in reference to the pressure drop, I will be testing the mechanical pump pressure with the electric fuel pump in line. Could you comment on the by pass system shown on one of the replies.

Thank you

Bruce

[Fred Zwicker #23106]

The reference for the voltage drop on the fuel pumps was from CEC#20099, not from Fred

[caddy60]

To C chleboun

Sorry, I was in error & should have replied to you & not Fred, I do thank you for your reply & If you read the note that I sent to Fred in error, I would appreciate your comments,

Bruce Watson