52 Lincoln, stock 317 Y block. When I bought it, it came with a inline fuel pump installed with a switch in the dash. The car still runs off the mechanical pump, this sits between the mechanical and the tank. Pretty slick, the car can sit for months and will start right up since it primes the system. That pump has finally died. Thoughts on using these? Am I supposed to leave it on or off after starting? If I turn it off is it impeding the fuel flow to the mechanical at all? I've tried driving it both ways and never noticed a difference. I'd like to put a new one on, any idea what PSI or GPH to go with?
You need to use a low pressure pump to replace the electric one as too high a pressure can destroy the diaphragm of the mechanical. Also the electric pump should not be run full time through the mechanical as if the mechanical pump diaphragm ruptures you will fill up your sump with petrol and potentially destroy your engine. So you should use the electric pump purely to prime or if you want to use it full time remove the mechanical pump and put on a plate over the hole in the block. There is no difference in flow running through most low pressure mechanical pumps. I run six volt so use an Airtex pump which make a pump perfect for your needs and has no resistance to flow. Hope this helps
I had one on my model a and got one now on my 51 merc flatty. Small round job i believe about 2 or 3 lb pressure flip the switch start it then i turn it off. Works great.
A mechanical fuel pump has a pump chamber that has a diaphragm that moves up and down and a couple of check valves to control fuel flow. If both pumps were running, the fuel pressure at the carburetor would be the greater of the two pumps and not the sum of the 2 pump output pressures. There is no harm in running an electric pump at the same time as the mechanical pump but the electric pump will make the car noisier and add to the electrical load on the alternator/generator. If your alternator/generator doesn't have a lot of excess capacity, you might notice that your headlights will be dimmer at idle. Some electric pumps are flow-through (like solenoid pumps) or not (like rotary vane pumps). You probably have a solenoid pump in your car because it seems to be inline with the mechanical pump and and the car runs fine when the electric pump isn't running. The simplest solution would be to replace the electric pump with another one that is the same or very similar. I would make sure that the electric pump has actually failed before replacing it. It could be that you have a problem with your power or ground wiring. See Vapor Lock for a list of suitable replacement pumps.
You use a pulse pump and not a more positive vane style pump. Yes you can run the pump while the engine is running. It is an old speed trick, they used to believe that the pulses of the mechanical pump was detrimental to the performance of your car. So the trick was to mount an electric between the tank and the electric pump this was supposed to maintain a more constant pressure. But with a standard pulse type of pump the fuel will flow though fine. Some will even say that you are better off not to use it while your engine is running because of you rupture the diaphragm in the mechanical it will flood your crank case with fuel.
It was pretty standard to put an electric "helper" pump on those 50's flatheads back in the mid/late 50's. Especially if someone had put the fuel pump pushrod in upside down and wore off the cam lobe. At least that is what my young at the time ears picked up back when my Step father had a couple of 52/52 Mercs. I think most parts houses can get a small low pressure 6 volt pump that isn't very expensive. Searching shows that the Airtex E8902 is popular with the Ford V8 guys. on Ford Barn https://www.fordbarn.com/forum/showthread.php?t=68443 More discussion here https://www.earlyfordv8.org/forum/printthread.cfm?Forum=18&Topic=4634 I found it on Amazon for a friendly price https://www.amazon.com/Airtex-E8902...8&qid=1534179962&sr=8-1&keywords=airtex+e8902
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