| fenbach | -- 04-16-2013 @ 5:45 PM |
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i just installed a 6V carter electric fuel pump in my '36 [macs part no. EFP-9350-6C] with a momentary switch, mostly to prime the carb. i thought the mech. pump would draw gas thru the elec. pump. it does at idle but not on the road. am i expecting too much of the mechanical pump? i'll just connect the elec pump to the ignition switch. but i've read about elec pumps dumping gas into the crankcase. is that enough of a risk that i should bypass the mech. pump altogether? thanks.
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| supereal | -- 04-16-2013 @ 5:59 PM |
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Most inline electric pumps allow fuel to be pulled through. Either your Carter pump isn't designed that way, or there is a check valve preventing the fuel flow. The inline pumps we use from C&G allow full flow when off. Some others don't. I 'd try contacting the manufacturer to get an answer. It is also possible your mechanical pump is weak. If it is old, alcohol gas may have damaged it. Your description also fits a fuel line plugged with rust and dirt. Run a test by disconnecting the fuel line at the carb, then with the end in a container, run the starter to see if a good fuel stream is present. Also be sure the flex hose at the firewall hasn't collapsed. An electric pump pushes fuel, while the mechanical pump pulls. Any restriction will reduce delivery by the stock pump. This message was edited by supereal on 4-16-13 @ 6:20 PM
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| Model B | -- 04-17-2013 @ 7:03 AM |
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I am using the Airtex E8902 6 volt pump for priming etc. along with stock mechanical pump. The E8902 is rated at around 2-5 lbs pressure, which is all you want for the old flatheads. Most of the electric pumps will develop 5-8 lbs of pressure so be careful. You might need a pressure regulator.
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| Old Henry | -- 04-17-2013 @ 8:27 AM |
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Unfortunately, the Carter pumps do not allow flow through. The Airtex that Model B mentioned is the one to use. But, even the Airtex rated at 2-5 psi often exceeds the 3.5 psi limit for the carburetor float and overran my carburetor float valve so I also had to put a pressure regulator in line to limit that pressure. The Holly is a good one and the one I use. http://macsautoparts.com/early-v8-ford-mercury-fuel-pump-pressure-regulator-holley-1-4-psi-3-8quot-npt-ford-9500-reg/camid/F30/cp/JS0R3CHL1140518/ Old Henry (The older I get, the better old looks.) This message was edited by Old Henry on 4-17-13 @ 8:28 AM
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| pfrancis | -- 06-07-2013 @ 8:51 PM |
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I wonder if someone would weigh in on fenbach's last question--what about the danger of having an electric fuel pump in line with the mechanical? This is because of the potential danger of a leaking diaphram allowing gas into the crankcase. Is there any way to allow the electric fuel pump to bypass the mechanical pump?
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| supereal | -- 06-07-2013 @ 9:07 PM |
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If the car runs well on the mechanical pump, it is likely OK. If the engine falters, but,picks up with the electric pump, a new mechanical pump is in order. If you have access to a gauge, the maximum fuel pressure should about three pounds. Usually, if a pump leaks, it is easy to smell gas at the breather.
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| 35ford | -- 06-08-2013 @ 4:38 AM |
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I think that some of the Carter pumps are Gear pumps which will not allow gas to flow through.m2csw.
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| TomO | -- 06-08-2013 @ 7:11 AM |
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" but i've read about elec pumps dumping gas into the crankcase. is that enough of a risk that i should bypass the mech. pump altogether? " The mechanical fuel pumps used on the flatheads have drain holes in the bottom section to allow the fuel to drain onto the engine if the diaphragm ruptures and you have an electric fuel pump pushing gas through it. This is a fire hazard, so if you smell gas, turn off the electric pump and get out of the car. Open the hood and use your fire extinguisher to flush the spilled gas. As long as the diaphragm is intact there should be no leakage into the oil pan or the engine compartment when an electric pump is in series with a mechanical pump. Gas can enter the oil pan through the carburetor if the float is overcome by the electric fuel pump. The electric fuel pump should be activated with a spring loaded momentary contact switch and through an oil pressure switch to stop the pump when the engine is not running. Tom
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| sturgis 39 | -- 06-09-2013 @ 12:52 AM |
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I do not like electric fuel pumps on old v/8s. I think they are more problems than they are worth. Buy a good pump and battery and you will do fine. Mine sit all winter long and will always start in the spring without priming.Checking and cleaning the fuel line is a good suggestion.I do not have a inline filter but the fuel pump has a sediment bowl which is easily cleaned. I have not experienced a vapor lock but I suppose I will some day. IF IT CAN NOT BE FIXED WITH BLASTING WIRE, DUCT TAPE OR JB WELD - IT CAN NOT BE FIXED This message was edited by sturgis 39 on 6-9-13 @ 12:59 AM
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| joe b | -- 06-09-2013 @ 6:59 AM |
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I replaced an electric fuel pump with a Carter EFP93506C I used the same switch and wiring as the other one. Had problems and after checking lines etc. I found it was running backwards. When turned on fuel was squirting toward the tank.I double checked the installation and the pump has an arrow printed on it to show direction of flow. It was installed correctly per this arrow. I thought that maybe since my Ford is positive ground I would reverse the wiring and it now works properly. Will this harm the pump in any way?
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| supereal | -- 06-09-2013 @ 2:53 PM |
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Most electric pumps have separate wires for the motor so it can be used in different applications. The usual effect of miswiring is to reverse the flow. They are usually color coded, red for positive, black for negative. Our old Fords have positive ground, so getting it backwards isn't rare. I have had an Airtex electric pump on my '47 for almost twenty years without a problem. I use it mostly to refill the carb, but it did get me home a couple of times.
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| joe b | -- 06-09-2013 @ 3:28 PM |
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Thanks,Super. After all the problems I have had I didn't want the d*mn thing to blow up on me !!
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