View Full Version : Fuel Pump Question

Michael Oritt
01-18-2007, 10:20 AM
If two FACET cube fuel pumps (nominal 2.5 psi) mounted in series were both operating would this double the fuel pressure?

01-19-2007, 05:36 AM
Very doubtful. Maybe a slight pressure increase in the line between 'em, but AFAIK it wouldn't be cumulative at the business end. You goin' for 'redundancy'? Put 'em on a DPDT switch: they will push thru/draw thru one-another. The units are relatively bomb proof in my experience, so having two running concurrently seems a bit of overkill.

01-19-2007, 07:56 AM
On one of my previous TR8 race cars, there were two facet pumps hooked side by side. I assume they were for redundancy as I did not build that car. When they were both turned on at the same time, I would get a surge in fuel pressure. It made the car run a little faster when they were both on. I thought that was great until the float bowls flooded and I had a nice engine fire.

01-19-2007, 03:03 PM
I don't know how the pump is constructed but the company literature says that is has pressure relief so I would tend to think that it would build up to the set pressure and thats it. It depends on how the internal relief is constructed. The company website is <a href="http://www.facet-purolator.com/" target="_blank">http://www.facet-purolator.com/ (http://www.facet-purolator.com/)</a> , they have contact info on there for technical assistance. It may be a mute point since the pumps should probably be separated and run as redundant pumps in parallel.

01-19-2007, 03:21 PM
if you run two pumps in parallel you need to use check valves inline in case of one pump failing. ON PAPER, two pumps in series will double the pressure ...but in reality they wont. Two pumps in parallel ON PAPER will double the availiable volume.

Any electric fuel pump, (or mechanical for that matter) especially with carbs such as Webers (down or side drafts) SU's and any carb that wants to see low pressure, NEEDS a pressure regulator. A decent regulator. Not the regulator that Purolator markets with the adjusable wheel. Were dealing with small increments of a pound in these carburetors and not + - a pound or so. and you need to set that pressure with a reliable gage and not "by ear".