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Posted By Discussion Topic: electric fuel pump     okydoky 11-14-2011 @ 11:59 AM reply profile send p.m. Member Posts: 11 Joined: Jul 2010 can anyone tell me how to install an electric fuel pump so that I can use the original pump & use the electric pump only when I need it. ford38v8 11-14-2011 @ 12:26 PM reply profile send p.m. Senior Posts: 2758 Joined: Oct 2009 The pump must be a "flow through" type, meaning that when turned off, the mechanical pump is able to pull fuel through the electric pump. Install as close to the tank as possible, usually atop the rear crossmember will be perfect. Install a fuel filter between the tank and the pump. Install a pressure regulator just after the pump. Some will screw directly into the pump. Set the regulator at 2 lbs. As you would need to massage your original fuel line to install the pump, and its condition being questionable due to the poor fuel we get these days, you would be well advised to install a new fuel line all the way through. Install a new fuel resistant flex hose from fuel line to mechanical pump on the engine. The best I know of is advertised in the V8 Times. In my opinion, get the one without the check valve. Do not use the spring loaded fuel line clamps as supplied in the fuel filter and fuel pump kits, as they virtually always, always leak. Instead, use the worm screw type found at all auto supply houses. Install a "normally open" toggle switch if you wish to use the pump to prime your carb. This switch will operate only when you push it wirth your finger. If you wish to use your electric pump on a continuing basis, connect a "normally closed" switch to the ignition switch. This setup will insure that the pump will not operate with the ignition off. Alan supereal 11-15-2011 @ 9:38 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 We use the Airtex electric pump sold by C&G. (800/266-0470) It is sold as either a 6 or 12 volt model as item 11A-9350-E6 or E12, as required. It is a "flow thru" type allowing the stock pump to be used, and has a check valve that fits into the tank end of the pump. It has the correct pressure, and doesn't need a regulator. It should be controlled by a separate switch so in the event of a leak, it can be shut off for safety. Mount it as close to the tank as possible, as these pumps are better at pushing fuel than pulling it. Use worm gear type hose clamps, rather than the spring clamps sold with the pump kit. There are two wires, one for ground, and the pumps come with instructions. We install the pump mount inside the driver's side frame rail for protection. Old Henry 11-15-2011 @ 9:39 PM reply profile send p.m. Senior Posts: 738 Joined: Apr 2010 Keep in mind that when you run two pumps simultaneously that are installed "in series" as described (your mechanical pump that always runs and your electric pump that can be turned on and off)it adds the pressure of both pumps to your carburator float valve when both are running. What that means is that if your mechanical pump is pumping 3.5 lbs which should be its maximum and you have a self regulated electric fuel pump that is limited to 4 lbs., you add those together and when you're running them simultaneously you have 7.5 lbs of pressure pushing on your float valve that will most likely overpower it, flood the carburetor bowl into the carburetor, and flood your engine. To solve that problem in my system, I installed the pressure regulator between the mechanical fuel pump and the carburetor so that, even if I'm running both pumps at the same time (which, for me, is only a short burst to "prime" my mechanical pump in case of vapor lock) the combined pressure will not overpower the float valve. Old Henry (The older I get, the better old looks.) okydoky 11-16-2011 @ 7:59 AM reply profile send p.m. Member Posts: 11 Joined: Jul 2010 Thanks Allen: I installed the airtex fuel pump per your instructions & it pumps very well. Thanks again. Now I have another problem. It will not cut off. checked all connections & installation. My car being positive ground, I grounded the positive wire from this pump. Could that be the problem, or might I have a defective pump? Thanks again, Nick supereal 11-16-2011 @ 9:31 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The Airtex pump slows down and eventually stops when the pressure limit is met, and occsionally pumps to maintain pressure. As long as the electric pump is pushing fuel thru the mechanical pump, the valves in the stock pump allow fuel to pass, and the diaphragm in the stock pump is moving, but with the valves held open by the electric pump flow, it is not additive. If the electric pump doesn't seem to ever stop, be sure that the float needle in the carb is actually closing when the bowl is full. As long as the engine is running, the pump will operate. Most of us use the electric pump to refill the carb after the vehicle has sat for a long time to reduce cranking time. Usually, it only needs to be run for about minute to do the job. After that, the stock pump will do its work, and the Airtex check valve will keep the stock pump primed. ford38v8 11-16-2011 @ 10:08 AM reply profile send p.m. Senior Posts: 2758 Joined: Oct 2009 Nick, a "normally open" toggle switch is spring loaded, like a doorbell. It only works as long as you keep pushing it with your finger. No way it could continue after you release it. You may have got hold of an incorrect switch. Another way the pump could continue to operate is if you have an air leak on the inlet side, or a puddle of gas under the car from a leak after the pump. A properly operating system will operate like this: You push the toggle and hold it, the pump operates fast at first, then slows down and stops. If your engine is not running, you can continue to hold the switch and the pump will not operate because the carb float needle valve prevents overfilling. In this day and age with the highly volatile fuel we get, I think all cars, classic or not, that are operated infrequently will need an electric pump. All, that is, except fuel injected or gravity fed like the Model A! Fuel evaporates so rapidly, a carburetor bowl will be dry after only a couple of weeks, putting the hurt on any mechanical pump. Alan Stroker 11-16-2011 @ 4:11 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 Okydoky: Supereal's explanation is certainly valid. If you had two centrifugal pumps in series as Ol' Henry has described, then "Ol's" analyses would be correct. As it is, the mechanical pump as provided on your motor will not "amplify" the pressure, as it will simply oscillate without actually pumping. We frequently discuss the merits of pressure regulators, but in fact all cam-actuated mechanical fuel pumps ARE pressure regulators. If the output pressure exceeds design specifications, the pump diaphragm simply "floats", and the pump push rod no longer has a load against it. So... a properly set-up stock fuel pump is all the pressure management anyone needs, IF the carburetor needle/seat is up to par. Adding an electric fuel pump as close to the tank as is practicable is a good idea, and I have done this since the 50's with a Bendix (no longer available) unit. I wired this as an "on-demand" booster, as at high altitudes, it seemed to help in avoiding fuel delivery problems caused by the fuel vaporizing in the fuel lines due to low Reid Vapor Pressure fuel. I think, given the wide-ranging RVP of our modern concoction's of available pump gas, an auxiliary pump is good insurance for getting where you want to go. It will not, however obviate the need for fuel pressure controls, if its' output pressure exceeds that of the stock fuel pump. okydoky 11-18-2011 @ 5:19 AM reply profile send p.m. Member Posts: 11 Joined: Jul 2010 Problem solved. Thanks to all you guys who are so knowledgeable & willing to share it. Thanks again. Nick

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