Electric Fuel Pump Question

LeroyM

LeroyM

Senior Member
I'm running a 6 volt electric fuel pump on a 12 volt system that I just got done converting over. Everything works fine and is 12 volts other then the starter and fuel pump. At idle with the fuel pump running the ammeter shows -15 discharge, when I rev it up some it shows that it is charging. If I disconnect the fuel pump for a minute the ammeter shows 0 when with the fuel pump running at idle it shows -15.

My question is would a 12 volt electric fuel pump have less draw at idle and make the ammeter hand show less of a discharge? This is a Model B motor by the way and the fuel pump is a Carter rotary vane type.
 
Changing to a 12v fuel pump may reduce the amperage draw. I would certainly change to a 12v for longevity reasons. Also, it might be useful to check the charging circuit and the output of your generator or alternator. Just a thought. Good luck
 
Any thoughts on a 12 volt fuel pump drawing less amps then a 6 volt fuel pump on a 12 volt system?

I'd like to know for sure before I buy a 12 volt fuel pump that won't make any difference on the -15 discharge my ammeter hand is showing at idle.

Any help would be appreciated. Thanks.
 
LeroyM said:
My question is would a 12 volt electric fuel pump have less draw at idle and make the ammeter hand show less of a discharge? This is a Model B motor by the way and the fuel pump is a Carter rotary vane type.
Click to expand...

How did you deal with the difference in voltage? Dropping Resistor or ?:confused:

A vane type Carter Pump does take a lot of Amps to run. A 12 Volt Pump should take APX 1/2 the Amps to run then a 6 Volt Pump.

I think a Carter Vane Pump may be overkill.

There are some inline pumps that take a lot less current to run and will give you plenty of fuel. Look in Mac's Catalog.

Also, just a thought, How about using a mechanical pump?

On my cars, I have an inline electric pump on a switch to initially prim the carbs after the car has been sitting for some time but depend on the mechanical pump for normal rumnning. I find this to work well.

I hope this helps,

Chris
 
I prefer the mechanical pump. If the car has been setting for a while and the gas has evaporated the starter will go on for a bit. That will make sure that some oil has been run through the system before the engine fires up.
 
CWPASADENA said:
How did you deal with the difference in voltage? Dropping Resistor or ?:confused:

A vane type Carter Pump does take a lot of Amps to run. A 12 Volt Pump should take APX 1/2 the Amps to run then a 6 Volt Pump.

I think a Carter Vane Pump may be overkill.

There are some inline pumps that take a lot less current to run and will give you plenty of fuel. Look in Mac's Catalog.

Also, just a thought, How about using a mechanical pump?

On my cars, I have an inline electric pump on a switch to initially prim the carbs after the car has been sitting for some time but depend on the mechanical pump for normal rumnning. I find this to work well.

I hope this helps,

Chris
Click to expand...

You may want to be careful in choosing what inline electric pump to use. Bought a '38 coupe a year ago that had that setup. Was driving it home from the seller's place when the car up and died while climbing a hill (in traffic of course). Turns out the electric pump got accidentally turned off and the mechanical pump couldn't pull enough gas through the system by itself. Found the switch to start the pump and it started right up. I think some electric pumps may have too much "flow resistance" built in. Maybe a bypass circuit around the electric pump with a check valve is the right answer.
 
I'm wondering how you are getting 6 volts.Years ago we used to put a screw middle of 12 volt battery.If you are running some sort of 6 volt power supply you maybe drawing more current.I would go the a 12 volts pump.
 
I ordered a 12 volt Carter rotary vane this morning. Theses pumps are built like a tank, I tried one of the little 12 volt cube style pumps but it died on me. I switched back to the 6 volt just to see if it would work after that and sure enough it did.

The Carter rotary vane type pumps have no contacts or electronics in them to stick or burn out from what I'm told.
 
I've got two different types of electric pumps, in two different types of cars. I have a 6V "Flow Through" type pump, with a switch under the dash, for the reason that CWPASADENA gives. I got it from Sacramento Vintage Ford, and it supplements the mechanical pump on the engine. When I turn it off, the mechanical pump pulls fuel through it. The other pump is a Carter 4070, and its in the car in my Avitar. Both are excellent pumps...
 
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