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Just installed and AIRTEX E8902 (2.5-4.5 PSI) inline elect pump for priming in a '39 - '12'.
It will not push fuel through the factory diaphragm pump.
Anyone else ran into this?
Wondering if i upgrade to an E8011 (5-8 PSI) it would push through
BUT then would the press. at the carb. override the Needle&Seat.

Factory pump reads at 3.5 PSI at starter motor RPM with good flow. Fills the bowl from empty to the 9/16 within 15-20 seconds

Several have used the 5-8 psi pump mounted near the tank. With the length of fuel tubing run and going thru the pump valves and pump filter screen or any optional filters, to my knowledge pressure at the carb has not seemed to be a problem with the slightly higher pumps. Some who had concerns also mounted a pressure regulator after the pump but no idea if they actually had to lower pressure much.

From the sound of it the valve springs in the stock Twelve pump must be fairly strong if they are not allowing the valves to raise and fuel to push thru. It almost sounds as if they would provide a fair amount of pressure lowering by themselves. IMO, it would be worth trying the higher output pump if it is mounted near the tank.

Have you cleaned the screen in the factory pump? I'd check it, along with any other filters or screens in the system. Also be sure the electric pump is connected properly as to flow direction and electrical polarity. Be sure the electric pump is primed with fuel.

I would think the electric pump would pump through the stock pump with no problems.

I also have a 1939 12, and have had no issues with the small airtex pumping through. Usually a flow regulator is not needed for the 12 models as I understand they have heavier duty needle and seats. As suggested check all screens and lines.

Todd
Know what AIRTEX model u have
E8902
E8011

I also have a 1939 12, and have had no issues with the small airtex pumping through. Usually a flow regulator is not needed for the 12 models as I understand they have heavier duty needle and seats. As suggested check all screens and lines.

Know what Model AIRTEX u installed

Quote:

I tried this approach before on my 37, as many have stated, to prime if it's been sitting awhile. Did some research and supposedly had gotten the correct electric pump (Airtex E8902),but when I would accelerate the car to about 55mph it would start to sputter. Seems like the fuel was being slightly restricted through the electric fuel pump. Rebuilt mechanic pump, pulled and cleaned the tank, new lines all before trying this. Pulled the electric fuel pump off and that fixed it. It would be nice to get a resolution though as it would be nice to have a pump to prime.

Tinman_70 had this same issue and I don't remember his fix but is probably detailed somewhere on his 49 project blog at the PAC forum. Think he found the orifice or fluid path going thru the pump was actually smaller than the 5/16 line. Several remedies were mentioned or considered and I believe he detailed all his experimentation, findings and what he did as a fix on his blog.