fuel pump

[PO51]

Need a little help on fuel pumps. I need to put a electric fuel pump on a 6 volt system, it needs to be very low pressure and low volume. There are a lot more 12 volt choices out there. My question is can you run a 12 volt pump on a 6 volt system? If so what do I need to look for? My Model A's don't have this issue!

[Old Henry]

Here is a picture of my installation as far back and close to the gas tank as I could get it. I didn't even have to drill a hole for the mounting bracket. I was able to use a hole already in the stock frame.

This pump is an AirTex 6 volt low pressure (2-4 psi) pump that cost me $60.00 available here: http://www.summitracing.com/parts/ATX-E8902/

[1934]

I have a similar set-up as Old Henry on my roadster. I put an on/off switch under the dash. Before shutting off engine I shut off the electric fuel pump to avoid any excess gas going to carb. Don't know if it's really necessary cuz it's a low pressure pump but I do it anyway.

[G.M.]

PO51 What makes you think you need an electric pump? If you have a problem descripe the symptoms and lets fix it. G.M.

[37 Coupe]

Originally Posted by Old Henry

Here is a picture of my installation as far back and close to the gas tank as I could get it. I didn't even have to drill a hole for the mounting bracket. I was able to use a hole already in the stock frame.

This pump is an AirTex 6 volt low pressure (2-4 psi) pump that cost me $60.00 available here: http://www.summitracing.com/parts/ATX-E8902/

Henry,is your 46 Ford 6 volt positive ground as original? I would assume it is looking at the black normal negative wire for power.I had bought one of these low pressure Airtex 8902 and was told it would work 6 volt positive or negative ground and it would only work negative ground. I was told to isolate pump from frame if using positive ground and this did not work either. I sent pump back and was told by supplier that it worked for him. I suspect some of the low pressure (2.5-4 psi) pumps are actually regular pressure 12 volt pumps that will supply low pressure on 6 volts but Airtex reps deny this. Yours does not look isolated from frame and I can see the tan positive line is grounded. As far as isolation I could hold pump in my hand and it would work touching black to negative post on bench and tan to positive but would not work switched to black on positive. I still would like to get one of these low pressure pumps to work as a backup. I had a very traumatic trip home a summer ago when mechanical pump failed ,a supposedly ethanol proof rebuild from a known rebuilder who promised ethanol proof diapraghm. I could have made it home on a backup electric or at least off a major highway to put on a spare I carried,however state patrol had other ideas and we road home two mile on a rollback.I had tools and spare but no safe place to work.

[Old Henry]

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Originally Posted by 37 Coupe

Henry,is your 46 Ford 6 volt positive ground as original? . . . Yours does not look isolated from frame and I can see the tan positive line is grounded.

My '47 is stock postitive ground. Pump works fine with wires reversed as you observed. Since it has its own ground wire independent of the pump body it doesn't need to be isolated from the frame and isn't.

[Old Henry]

Originally Posted by 1934

I have a similar set-up as Old Henry on my roadster. I put an on/off switch under the dash. Before shutting off engine I shut off the electric fuel pump to avoid any excess gas going to carb. Don't know if it's really necessary cuz it's a low pressure pump but I do it anyway.

I still use stock mechanical pump without the electric pump except when I get vapor lock and need to "prime" the mechanical pump for an instant to get it going then shut the electric pump off. I don't run the electric pump constantly.

[PO51]

Thanks for all your input. I agree with G.M. we would like to fix the problem. The issue is this is for a 1921 Nash Touring car, it has a rear gas tank and a vacuum fuel pump on the firewall. We have not had much luck rebuilding the pump. Our thinking is if we install a inline electric pump that is low pressure and low volume we can use it as a back up and or as a assist.

[G.M.]

PO51 I haven't worked on a vacuum pump for years and can't get a clear picture in my mind of them. I do remember they are fairly simple to fix. You need to find some people with the teens cars that have these types of pumps. A lot of time parts companies that handle parts of that time frame can put you in touch with someone that fixes or has parts for them. G.M.

[Old Henry]

Originally Posted by 37 Coupe

As far as isolation I could hold pump in my hand and it would work touching black to negative post on bench and tan to positive but would not work switched to black on positive.

The pump does have to be hooked up black to negative and tan to positive as you said. It won't work the other way around as you have discovered. But, as you mentioned from my picture, that is exactly how mine is hooked up - black to the negative coming from the switch I installed under the dash board that comes from the ignition switch and tan to ground which is positive.

[Harylufa]

Dear Henry!
Have you got both fuel pump? if mechanical pump fail, you use the electrical one?
I have installed electrical, but it is disconnected. Now I am using the mechanical pump only, but electrical push more than 7 psi. I disconnected it because it need a return to the fuel tank.
I think that I should install the electrical system in case the mechanical one fails. I need to put a switch? or How to to make the connection to pass from one to the other.

Harylufa

[Old Henry]

Originally Posted by Harylufa

Dear Henry!
Have you got both fuel pump? if mechanical pump fail, you use the electrical one?
I have installed electrical, but it is disconnected. Now I am using the mechanical pump only, but electrical push more than 7 psi. I disconnected it because it need a return to the fuel tank.
I think that I should install the electrical system in case the mechanical one fails. I need to put a switch? or How to to make the connection to pass from one to the other.

Harylufa

I have both pumps but I only use the mechanical one unless it fails which has only ever been from vapor lock. If the mechanical pump ever doesn't pump then I turn on the switch for the electrical one just long enough to prime the mechanical one to get it to work then turn off the electric pump. If that is all you ever used your electic pump for you could hook it up and use it. The excessive pressure wouldn't hurt for that very short time until the mechanical one takes over then shut off the electric pump.

[37 Coupe]

Originally Posted by Old Henry

The pump does have to be hooked up black to negative and tan to positive as you said. It won't work the other way around as you have discovered. But, as you mentioned from my picture, that is exactly how mine is hooked up - black to the negative coming from the switch I installed under the dash board that comes from the ignition switch and tan to ground which is positive.

Now I am really confused.

[Adam/Mill Valley CA]

Old Henry, I recently put the same Airtex E8902 in my '36 (also positive ground) to serve as an emergency backup. I've put a short length of rubber fuel hose between the metal line from the tank and the inlet to the fuel filter (which sits ahead of the pump), just to make it easier to clamp off and change the filter

Adam