Electric Fuel Pump Alternate View

[Brad Ipsen CLC #737]

The topic of electric fuel pumps has been a recent subject on the message board and in the “Self-Starter”.  Adding an auxiliary electric fuel pump has become such a given that there is not even discussion of whether it is really needed or not.  I have never installed an auxiliary pump in any of my cars in the last 30 years including a 29 Hudson with a vacuum tank.  This has included a 39 Cadillac V-16, Cadillac 40-60S, 29 Hudson, 35 Hupmobile.  The 39 V-16 has been in 105F heat climbing out of Redding, CA and the 40-60S has been in the MT mountains in Yellowstone and Glacier National Park in the heat at altitude.  The biggest problem without an electric fuel pump has been the starting up after the car has sat for a period of time.  After about 2 weeks the gas has evaporated (or leaked) out of the bowl so you have to crank the engine for an extended period of time to get the bowl filled again.  This has almost made me give up my stand on not adding an electric pump several times.  Certain British cars had this one solved by putting a hand override on the mechanical pump so you could manually stroke the pump.  Anyway by accident I finally discovered the solution to this one problem.  On the first start after sitting you crank the engine about 5 to 10 seconds and then just get out of the car and spend a couple of minutes doing something else such as checking the oil level before going on your way.  Apparently the vacuum created on the suction side of the mechanical pump needs some time to move the fuel up from the tank.  After this happens the positive side of the pump can then act quite quickly to pump gas to the bowl.  In any case it seems to work.  I think all of the elements that Cadillac designed into the fuel system at least in the late 30’s and 40’s cars that I am familiar with are important.  The suction line size to the pump is 3/8 inch.  No filters on the suction side of the pump.  The line from the fuel pump to the carburetor is insulated with a black woven insulation.  At first glance this would not seem to be needed on the plus pressure side of the pump.  The greatest problem that I have seen is the hot soak with a very hot engine.  The case was in MT, high in the mountains on a hot day at a construction road block with the 40-60S.  I just wasn't sure whether to turn the engine off or keep it running.  I decided to turn it off.  With no fresh fuel flowing, all of the engine heat then starts heating up the gasoline in the under hood lines and carburetor bowl.  Insulation on that gas line to the carb would be of help for a short period of time in this situation.  Insulation will never keep things from reaching temperature equilibrium but it will slow the process down.  In this case the road block turned out to be relatively short.  The car started right up but coughed a couple of times in getting going.  The car cleared and ran normal after a very short time period. 
There can be problems with a mechanical fuel pump that mimic the symptoms of vapor lock.  Since the cost difference between a fuel pump kit and having that same vendor rebuild the pump is small I have always been inclined to have the vendor do the whole job.  In debugging the 40-60S after restoration I was having symptoms like vapor lock in the car at all times in the cool weather here in WA.  This did not make sense.  After a lot of trouble and denial by a well-known east coast fuel pump kit supplier the problem turned out to be the wrong length rod was installed in the fuel pump and it did not have the full stroke.
Besides having all of the elements of the original Cadillac design the system has to be clean like it was when the car was new.  You can't have any crud partially blocking lines.  The fuel has to be suited for the season of the year.  The vapor pressure of gasoline/ethanol now seems to be a big question.  From what I can determine vapor pressure is highly regulated by the EPA.  In the summer low vapor pressure will minimize the amount of evaporation into the air.  In all modern cars and storage facilities this is not an issue since all have vapor recovery systems.  From what I can find on various web sites the CA summer EPA vapor pressure requirement is about 7psi.  In my 60’s vintage internal combustion engine textbox a number of 7psi for summer and 10psi for winter is listed as typical.  In other words the vapor pressure has not changed much at all.  I think the EPA winter vapor pressure requirement is relaxed so carbureted cars will still start well.  If you have winter gasoline in your car and don’t burn it off before summer this can cause vapor lock problems from the higher vapor pressure.  On the Chevron web site they state that the typical ethanol content is about 5% which results in a lean out of 2% to 3% because of its lower energy content.  I have never noticed a problem from this lean out since I suspect the old cars were set up slightly rich anyway.  If ethanol is to be added to gasoline they adjust the vapor pressure of the gasoline to account for this later addition.  As a point of interest the vapor pressure of gasoline is very complicated because it is a mixture of many compounds each with its own vapor pressure.  Ethanol is simple since it is one particular compound of carbon, hydrogen and oxygen.  Its vapor pressure is really quite low at about 2 psi. 

[CEC #20099]

Brad, Thanx for your comprehensive comments. In Chicago, we have some of the worst reformulated gas in the country. It is all 10 percent ethanol, & govt is talking 15 percent to appease the IL/IA farmers. I have Elec pumps on virtually all my carb cars, EXCEPT the 74 Ply Slant 6. Every slant 6 I have ever had , can sit for months, & start right up. Look at the fuel filter location. It is a key point.

I also had a serious disagreement with a certain East Coast Fuel Pump Rebuilder concerning fuel pressure on my 39 Buick. He is very unreasonable to discuss complaints with. Sounds like the same guy.

5 percent ethanol. Wow, wait till you get 10 percent.

I have to run elec pumps, to start the cars, & to control vapor lock.
c chleboun #20099

[robert G. smits]

Brad, thank you for the excellent discussion.  I admire your faith in Cadillac's original fuel system.  Many of us accept the concept that our cars are not in "perfect" condition at all times.  Many are driven once or twice a year if at all.  We look to the electric fuel pump as insurance.  As I have said before my wife will tour in a non air conditioned car as long as it is MOVING.  Nothing is worse than a roadside failure on a 100 degree day with your wife in the car.
Bob Smits #2426

[robert G. smits]

I finished the electric fuel pump installation Friday evening.  THANK YOU to everyone who gave me advice.  On Saturday my wife and I took two guests on a CCCA day tour in central Texas.  The Temperature hit 101 about two in the afternoon.  The car performed flawlessly on the mechanical pump until I had to sit at a stop light for a couple of minutes and it began to vapor lock.  I turned the electric pump on for no more than 2-3 minutes and the engine smoothed out immediately.  Would it have stalled, I don't know.  I am just glad I had the insurance.  To me having an auxillary pump is no different than taking two spare tires when you haul a car across country.
Bob Smits #2426

[Steve Passmore]

Hi Brad,  I just wanted to say that I agree with you 100%.  When people talk about vapor lock and Cadillacs overheating I say to them that Cadillac could not have sold cars that couldn't cope with high  temperatures when they were new, THEY HAD TO COPE!
When doing my restorations the block is completely dismantled, waterways sand blasted out and pressure washed and a new core in the rad, as it was when it was new, invariably when I do these engines (and its not just Cadillac) the waterways are near solid at the rear cylinders, and the rads have less that 100% flow rate.   I have never had vapor lock or overheating on any car Ive restored in this way, and I have never fitted an electric pump,  admittedly I live in cooler England, but Cadillac had to design it to do the job.   having said that, Robert Smits hit the nail on the head when he said "  Our cars are not always in perfect condition " and theres the rub,  Iv Just purchased a 37 V12 that I don't intend dismantling, it was restored 30 odd years ago, it has electric pumps fitted and I strongly suspect it will need it when it gets hot.

[Jim Stamper]

     My 37 coupe has never overheated or vapor locked either, even on 90+ days. A clean block and some time for the radiator in the radiator shop is what I attribute cool running temperatures to.

                                                  Jim Stamper CLC#13470

[P W Allen CLC# 20193]

Steve, I had this happen a few times with my 53. It turned out that the carburetor float was occasionally getting stuck in the full up position. This would cause the car to literally run out of gas. It acts just like vapor lock, but it wasn't in my case. A little tap on the side of the bowl would free it up, and off it would go. I should mention that this was a newly overhauled Rochester carb. It happened about three times and eventually stopped doing it. Haven't had a problem since. 7 or 8 years now. If in your case it was vapor lock, you may want to consider installing an electric fuel pump back at the tank to supplement the mechanical pump. You can then switch it on when you need it. I purchased a Carter electric pump, model #P60430 for my car, but I have yet to install it.

Paul

[Jay Friedman]

My '49 Cad with a stock 331 motor, Carter WCD 2-barrel and mechanical fuel pump, along with an original fuel line and fuel filter, never vapor locks and starts easily on the hottest Geaorgia summer days, even with 10% ethanol fuel (87 octane regular).  I haven't installed an electric fuel pump but I do keep up the 6 volt electrical system, especially the battery cable and grounds. 

On the other hand, my other old car, a stock (not rodded) '32 Ford V8, does vapor lock if driven slowly, such as in parades in hot weather.  It's not due to ethanol, since early Ford V8s have been notorious for this since they were new, so I installed an electric fuel pump which usually helps.
 
My daily driven 79 VW Rabbit (bought new), which has an aftermarket Weber 1-barrel carburetor and an electric fuel pump, does vapor lock due to ethanol in hot summer weather.  Following the advice of several people, including John Washburn, I cure it by pouring a little Sta-Bil in the fuel tank at each fill up. 

[R Sotardi #11719]

Paul, Watch out for that Carter P60430. Of course it is for 12 volt, but if you plan to put it in line with the mechanical fuel pump, be advised, the mechanical pump will not be able to "suck" fuel through it. It is a gear driven pump and not a "free Flow". A bypass before and after the electric pump with a check valve will be needed. Nice pump, however, but it must be used as a only fuel source and probably with a pressure regulator. Tried it on my Hudson. They were used on Chevettes, Luvs etc

[Fred Zwicker #23106]

About a year ago, my '55 Pontiac Safari fuel pump failed , probably due to gunk from ethanol.  1955 Pontiacs have a 12-volt system.  As the car was going to Glenmoor the next day, we stopped at our local auto supply store for a generic fuel pump and purchased a Carter P60430 and quickly installed it in the motor compartment to get to Canton, Ohio and back (about 60 miles each way).  Later, realizing that electric fuel pumps push better than pull, we moved it to the rear of the car near the gas tank.  We disconnected the fuel line to the original mechanical pump, using the electric pump alone. I think the Carter P60430 is rated at 6 PSI.  This pump is wired through the ignition and an on-off switch under the dashboard.

I also have a 1958 Lincoln Continental and it previously had a Bendix 12-volt electric fuel pump that was installed  by the prior owner in the engine compartment, and the mechanical fuel pump was not hooked up.  This electric fuel pump was also clogged , so we installed new fuel lines and had the gas tank"renewed". We then removed the faulty electric fuel pump from the engine compartment and installed a new Carter P60430 electric pump near the gas tank.  I had the mechanical pump rebuilt and plan to  connect it to the fuel line from the electric pump in the rear and then to the carburetor.  Once hooked up, hope to use the electric fuel pump for priming only.

In view of R. Sotardi's comments about the P60430, am wondering if my mechanical pump will pull fuel through the P60430? The P60430 does not look like a gear driven pump to me (is about 2" diameter and about 4 or 5" long). See attached picture.  I thought the Carter P60430 was an "impulse pump" ??  Both of my above cars are wired through the ignition switch and also through a secondary on-off switch below the dash.  Neither use a pressure regulator and both perform flawlessly. I do not use a relay, nor do I use an oil pump pressure switch, as some recommend.  I later plan to add a similar setup to a 1947 Ford (6-volt), but will use a relay for that hookup, since 6-volts draw more amperage.

Has anyone on this forum used a Carter P60430 or Carter P60504 12-volt electric fuel pump in conjunction with a mechanical pump without any type of bypass or check valve setup?  (Both the P60430 and P60504 look about the same, although the P60504 is rated at 4 PSI)  I have such a setup on my 1939 LaSalle, using the electric fuel pump for priming purposes only, and running off the original mechanical fuel pump (no check valve or bypass).  The electric fuel pump is near the gas tank.  This is a 6-volt system.  I do not recall the name or part number of this electric fuel pump, although purchased it from Coopers in California a few years back.  I did not use a relay on the LaSalle, although plan to add one in the near future, due to it being a 6-volt system.

In any case, since my cars sit for extended periods of time, feel that an electric fuel pump is perfect for priming the car and then can be shut off and let the mechanical fuel pump be used.  (No more removing the air cleaner and pouring in gas or starting fluid into the carburetor).

Fred

[P W Allen CLC# 20193]

Fred,

I was also confused by that post. I was under the impression that it WAS a flowthrough type that the mechanical could pull through when the Carter was not running. That's why I bought the P60430. NOW I'm not sure! I checked around yesterday for some information on it, but really didn't find much. I hope others chime in with more info.

Paul

[Fred Zwicker #23106]

I finished the electric fuel pump installation Friday evening.  THANK YOU to everyone who gave me advice.  On Saturday my wife and I took two guests on a CCCA day tour in central Texas.  The Temperature hit 101 about two in the afternoon.  The car performed flawlessly on the mechanical pump until I had to sit at a stop light for a couple of minutes and it began to vapor lock.  I turned the electric pump on for no more than 2-3 minutes and the engine smoothed out immediately.  Would it have stalled, I don't know.  I am just glad I had the insurance.  To me having an auxillary pump is no different than taking two spare tires when you haul a car across country.
Bob Smits #2426

Bob - What is the make, part number and voltage of your electric fuel pump and did you install a bypass fuel line with check valve?  It seems as if there are some mixed opinions on this.  On my '39 LaSalle I installed an electric fuel pump for starting purposes and turn it on until engine starts - then shut if off and the engine runs well with the mechanical pump.  It has been about 4 years, so I want to also check to see what pump I installed (6-volt system in the '39 LaSalle).  I did not install a bypass valve or check valve.

Fred

[P W Allen CLC# 20193]

I have some more information on the P60430. I purchased mine from the gentleman below. I had asked him about the ability of the mechanical fuel pump to pull through the Carter. His reply as follows.




Hello Paul;

Many of the customers who have purchased this pump have run it straight
through the pump, as you suggested, and for the same reasons.  I have
never heard from any of them that the mechanical pump would not pull
through the electric pump.  The only potential disadvantage I know of in
installing it this way is that, if you decide to run the engine on the
electric pump and the diaphragm goes bad on the mechanical pump, you could
get quite a leak externally or into the crankcase from the leaking
diaphragm.

Hope this has been helpful.

Take care.

Hal Houghton
The Classic Preservation Coalition

[Fred Zwicker #23106]

Testing Information - Carter vs. Airtex:

I bought a P-60504 Carter Fuel Pump which is about the same pump as the P-60430 except that it operates on slightly lower pressure. Cost is slightly higher than the P-60430, but in appearance they are identical.  I also bought an Airtex 8012 Fuel Pump. Both pumps were 12-volt versions.  I did not yet install either pump as yet, but here is what I found.  This is called the "Fred Zwicker" test  (Not scientific, but significant when comparing the two pumps below).

Here are the tests on the Carter P-60504:  (Carter P-60430 should be the same).

I stuck the outlet side of the pump in a small can of water and blew air through the pump from my mouth with as much force as possible.  A few tiny amount of bubbles were noticed, but not a free flow of air as I was hoping for. There was plenty of resistance - almost no air was getting through the pump.

I then removed the pump from the water, dried it out and then with all of my lung power, sucked on the outlet side of the pump to see if I could pull any air through the pump.  I am not sure how much suction I was able to furnish, but there was only a very small amount of air pulling through the pump.  I did not feel that there was enough air being pulled to properly operate a car, especially when under a load such as rapidly accelerating or driving up a hill.   My conclusion was that I did not want to install this pump and I did not do so.


Here are the tests on the Airtex 8012:

I stuck the outlet side of the pump in a small can of water and blew air through the pump from my mouth with as much force as possible. There was NO RESISTANCE - plenty of air was blowing through the pump.

I then removed the pump from the water, dried it out and then with all of my lung power, sucked on the outlet side of the pump to see if I could pull any air through the pump.  I felt NO RESISTANCE and plenty of air was pulling through the pump.  I was amazed at the difference. My conclusion is that I plan to install the Airtex Pump and if it works as expected on the first car, I will install it on others that require help.

I like to use the original mechanical pumps for normal operation, but like an electric pump for priming purposes and for use in the rare instance that I should get vapor lock.  I run the power off the ignition switch through an in-line fuse to a secondary on-off switch and from that switch to the electric fuel pump near the gas tank.  Some suggest a spring-loaded on-off switch for this purpose, which is a good idea, although in the case of vapor lock or should the mechanical fuel pump fail, a simple on-off switch might be better.  I have this setup on one car and have no trouble in remembering to shut off the electrical fuel pump as soon as the car is running.

For those who want to use an electric pump instead of the original mechanical pump, suggest that the electrical pump be near the gas tank and a fused on-off switch installed as described above, but run the fuel line directly from the electrical pump to the carburetor.  The mechanical pump should either be left on the engine as an ornament, or removed and a flat plate installed to block the opening.  Some will "gut" the inside of the mechanical pump so that the original appearance is maintained, but if doing so, be sure that there is no possibility of fuel leaking into the engine.

Some users suggest installing a relay to provide power to the electric pump, but I have not had need for a relay on a 12-volt system, as the amperage is fairly low.  Due to higher amperage with a 6-volt system, I would probably add a relay, or if not, would run a 12-gauge wire to the fuel pump.  Others have suggested running the power through a switch on the oil pressure line, which isn't a bad idea, but is one more thing to fail.  In my case, since I am running the electric fuel pump for starting purposes only, do not feel the need for this.

Fred

[robert G. smits]

Fred, I just returned from Italy yesterday.  I will be going to the shop tomorrow to start getting the 41 ready for the 2011 Glidden and will post the fuel pump information.  Bob Smits #2426

[Fred Zwicker #23106]

Bob Smits Quote: "I finished the electric fuel pump installation Friday evening.  THANK YOU to everyone who gave me advice.  On Saturday my wife and I took two guests on a CCCA day tour in central Texas.  The Temperature hit 101 about two in the afternoon.  The car performed flawlessly on the mechanical pump until I had to sit at a stop light for a couple of minutes and it began to vapor lock.  I turned the electric pump on for no more than 2-3 minutes and the engine smoothed out immediately.  Would it have stalled, I don't know.  I am just glad I had the insurance."  To me having an auxillary pump is no different than taking two spare tires when you haul a car across country.  Bob Smits #2426

Second Quote:  ""Fred, I will be going to the shop tomorrow to start getting the 41 ready for the 2011 Glidden and will post the fuel pump information.  Bob Smits #2426"

Thanks Bob - need to know the voltage, name and part number of your electric fuel pump which is used in conjunction with (not instead of) your mechanical pump. I have prepared a detailed notebook on the subject, listing every 6-volt and 12-volt electric fuel pump that I have found and hope to determine the following on each pump.  Any input that you can provide will be helpful, as there are many things to consider prior to installing an electric fuel pump.  Here are most of the factors to consider and there are probably more.  I feel that figuring this out in advance as much as possible is better than the expensive and time-consuming "trial and error" method.  Unfortunately, most vendors who sell electric fuel pumps provide skimpy specs, and few are knowledgeable when it comes to knowing too much about what they are selling.

Source (Vendor name or names, addresses, etc.)
Pump Mfg (Airtex, Bendix, Carter, Delco that I have found):
Part Number or Numbers (some sellers have their own part numbers)
Voltage and Amperage:

Type when in the off position (Flow-Thru or Non-Flow-Thru) - this is very important:
Working Pressure Range - some pumps require a pressure regulator - also important:
  ^ Note that different vehicles and carburetors require different pump pressuresPicture if possible (or description):

Is a filter included with pump?  (If not, recommend this)
Cost:
Mounting information (most recommend mounting in rear near tank):
Wiring recommendations (switch or switches, relays, wire gauge, etc.):
Is a bypass required? (A non-flow through pump would require this).
Other:

Installing an  electric fuel pump is not an easy decision.  Some want the pump to be the only source of fuel (This requires bypassing, eliminating, gutting or blocking the mechanical pump).  Others want the electric fuel pump to be used for priming purposes only and if so, a "flow-through" pump is necessary, or the mechanical pump will be unable to supply adequate fuel to the carburetor when electric fuel pump is in the off position.

Some users have reported repeated problems with electric fuel pumps, while others have had them last for years.  In my opinion, the condition of the fuel tank and fuel lines is a contributing factor of premature fuel pump failure (mechanical or electric pumps).  Older cars often sit for years and the fuel tanks are full of gunk, lines are partially or fully clogged, filters are clogged, etc.  Prior to installing a new or rebuilt fuel pump, all of this must be carefully considered.   While it is a lot of work, I have been removing gas tanks for cleaning (I use Gas Tank Renu) and replacing the fuel lines and fuel line hoses - and never regretted it.   With the Ethanol now used in fuels, the problem is compounded.

Fred

[robert G. smits]

Fred, It was good to get back to working on an old Cadillac although I missed my Italian food and wine for lunch.  The pump I installed on the 41 is an Airtex, Carquest# E8016s.  This is a 12 volt unit as my 41 was converted to by the PO.  I mounted it on a special bracket  just in front of the outlet to the 41's gas tank.  I did not use a bypass, check valve or regulator.  This pump produces 2-4.5 psi.  They also have a similar pump, E8012s which is a 5-9psi pump.  Prior to instillation I hooked the pump up to my Miti-vac and could detect no significant restriction.   I use the mechanical pump as the primary pump and pull through the electrical pump.  The pump has a off-on switch and is wired through the ignition using #12 wire. The 6 volt is E8011 which is a 5-8 psi pump.  All three pumps have a filter attached and retail around $60 at Carquest. 

[Fred Zwicker #23106]

Thank you Bob - From info in your earlier post, I assumed that you had an Airtex pump, as they seem to be the best choice if using an electric fuel pump for priming the carburetor (or as a standby), since the fuel can be easily pulled through the Airtex by the mechanical pump.  The Carter P60430 and similar pumps do not allow fuel to pump through when using the mechanical pump, although some (restricted) flow is possible.  Howeveer if using an electric pump only and not using a mechanical pump, the Carter P60430 and similar pumps are always a good choice as they are excellent pumps.

I will add your information to my notebook, which is nearing completion.  In the meantime, looked through some catalogs that I have and the information  given is very brief - most just stating it is a 6-volt or 12-volt pump and none mention anything about whether the pump can be used in conjunction with a mechanical pump.  Imagine the time spent to hook up an electric pump and find that it will not work with the mechanical pump.  Too often we jump into what starts off as a simple project and find out later that it wasn't as simple as planned.

Fred

[Fred Zwicker #23106]

Here is a nice chart on Airtex Electric Fuel Pumps, showing 6-volt and 12-volt applications.  I like the specs of the E8016S that Bob Smits used for his 12-volt car for starting purposes only.  It is my understanding that the Airtex Solenoid pumps are "free flow" and fuel can be pumped through them with the mechanical pump while the solenoid electrical pump is in the "off" position.

I wish I could locate a 6-volt solenoid pump at the same low pressure range as the E8016S (2.5 - 4.5 psi), but Airtex does not list such a pump on the chart at link shown below.  Airtex shows a model E8011 in a 6-volt version, but operating pressure is 5-8 psi - probably too high for most older cars with a carburetor. If I go that route, would need a fuel line regulator and am wondering if such a regulator is available for the lower pressure ranges.  Also not all fuel line regulators have a port for a gauge, so might be hard to fine-tune.

http://www.airtexproducts.com/TSB/TSB-0108-01_ATX.pdf

* Update:  In addition to the Airtex Fuel Pumps listed at the above link, Airtex also makes a 6-volt pump that produces 2.5 - 4 PSI.  Part No. E8902. I just ordered two from Summit Racing in Akron @ $48.95 each.  Sales person told me that they were being shipped from Airtex and that I could expect delivery within 5-7 days.

Fred

[robert G. smits]

Fred, thank you for all the work you have put into this thread.  I am taking the 23 on next years Glidden Tour which is out of Brenhan, Tx.  I plan to convert it to an "electric only" set up this winter and also add an electric emergency pump to the 32 which my daughter will drive.  It is great to know there is a 2.5 to 4.5 psi 6 volt Airtex available.  I would agree with Brad's original thesis that Cadillacs shouldn't need an auxillary pump if restored back to factory specs however my 41 and 32 have never been touched since new and I plan on keeping them that way.  Bob Smits #2426