Wiring Path for Electric Fuel Pump

[BlackBirdPilot]

Ok. Im starting to understand how this works. Found the two relays. I see how they are connected. Now, it seems that im not getting power to relay A.

So im trying to understand the chain of events that trigger the fuel pump.

[SteveJ]

Relay A is energized by a wire between the alternator and regulator. When the engine is running, the alternator is turning, and the coil is powered.

When the contacts for Relay A closed, Relay B's coil is energized.

If someone removed the harness that energized Relay A, Relay B will never get power on the coil. This might be the case if someone converted the alternator to an internally regulated unit and removed the voltage regulator. After that conversion, Relay A will always be energized unless the harness for Relay A is removed. That will run down the battery.

Been there.

Done that.

Got the t-shirt.

[Captain Obvious]

[SteveJ]

I don't think I would look that good in that T-shirt. Does it come in 2XL?

[Captain Obvious]

Haha!!

[BlackBirdPilot]

So then, how dose the pump engerize from a cold start? Will A engerize while cranking, untill the Alt starts charging?

If the Alt fails to charge, will the pump cut out?

[SteveJ]

So then, how dose the pump engerize from a cold start?

The electrical pump doesn't pump at the start.

Will A engerize while cranking, untill the Alt starts charging?

No.

If the Alt fails to charge, will the pump cut out?

Yes.

Remember, the mechanical pump is the primary pump. The electrical pump was integrated in to deal with issues associated with the flat top carburetors.

[jalexquijano]

Does anyone knows what could be the main causes for the electric fuel pump to get toasted, damaged or loose pressure? If you leave the car with the radio on and the fuel pump running i guess this would ruin the fuel pump! I have replaced an Airtex 8012S twice this year due to the lost of fuel pressure!

[Chickenman]

Does anyone knows what could be the main causes for the electric fuel pump to get toasted, damaged or loose pressure? If you leave the car with the radio on and the fuel pump running i guess this would ruin the fuel pump! I have replaced an Airtex 8012S twice this year due to the lost of fuel pressure!

Because newer pumps use a Ceramic Turbine design instead of the old roller vane style, you absolutely MUST run an auxilary fuel filter before the pump. A Fram G3 will work.

 

The newer turbine style pumps are more efficient and quieter than the older roller vane styles... but they have much tighter clearances inside and will not tolerate dirt particles. Dirt that would pas straight through a Roller Vane pump, will jam a Turbine pump or damage the components inside resulting in a loss of pressure.

 

#1 failure of new style Turbine pumps is debris getting into them.

 

Edit: The instructions for Airtex ( and all other Turbine impeller fuel pumps ) state that the Fuel tank should be drained and cleaned before installing the new pump. Very few people actually do that and suffer the consequences. An auxiliary F/Filter before the fuel pump works in most cases, but a really dirty fuel tank will ruin a new pump if dirt gets past the inline filter.

Edited November 4, 2015 by Chickenman

[black gold man]

Did you test volts at pump or put 12 volts to your bad pump to see if it works..

[jalexquijano]

the bad E8012S Airtex pump does work but makes less noise compared to this new one! I just connected it to the 12 V battery and it does work. What other test shall i perform?

[jalexquijano]

On ‎11‎/‎04‎/‎2015 at 2:57 PM, Chickenman said:

Because newer pumps use a Ceramic Turbine design instead of the old roller vane style, you absolutely MUST run an auxilary fuel filter before the pump. A Fram G3 will work.

 

The newer turbine style pumps are more efficient and quieter than the older roller vane styles... but they have much tighter clearances inside and will not tolerate dirt particles. Dirt that would pas straight through a Roller Vane pump, will jam a Turbine pump or damage the components inside resulting in a loss of pressure.

 

#1 failure of new style Turbine pumps is debris getting into them.

 

Edit: The instructions for Airtex ( and all other Turbine impeller fuel pumps ) state that the Fuel tank should be drained and cleaned before installing the new pump. Very few people actually do that and suffer the consequences. An auxiliary F/Filter before the fuel pump works in most cases, but a really dirty fuel tank will ruin a new pump if dirt gets past the inline filter.

Chickenman,

Thanks for your clear advice given a couple of years ago. I am going again through this same situation with the Airtex 8012s pump. THis is the 4th pump i replace and always due to loss of PSI. Always the same thing. I did noticed that this pump has a Steel filter fastened to it, so even cleaning it will lead to the same loss of PSI?? What if i remove that Steel filter and fasten a fram g3 instead? Right now i am at 3.2 psi and initially when new it measured 4.2 psi.

https://www.summitracing.com/int/parts/atx-e8012s/overview/