SW 240A Fuel Pumps - Page 5

Dominik · #81 (**permalink**) 06-16-2013, 04:16 AM

Interesting reading...

I am still "baffled" by having a reserve amount in a racing tank.
Was the amount of reserve designed to last one lap? For which track?

42 gal last for (I am guessing) 2 hours of racing? I can understand that calculating the amount of laps from that differ quite a lot. That answers above question.

Are there now two SW pumps for the reserve? Why not only one, if it had to last one lap only? I suppose one or two pumps don't add much to the weight of a 42 gal tank full of fuel...

Which reminds me, I have two of those unused since years (from new?) somewhere in my garage!

FatBoy · #82 (**permalink**) 06-17-2013, 07:21 AM

Quote:

Originally Posted by Dominik

I am still "baffled" by having a reserve amount in a racing tank.

You and me both, but the evidence does seem to point that way.

I had another pair of pumps that I cleaned and polished and I've now fitted those to match the polished body:

Paul

FatBoy · #83 (**permalink**) 03-09-2014, 12:22 PM

I've eventually got my pumps all correctly plumbed in and working and I ran them for the first time today in the car with fuel.
Can someone with experience of these pumps confirm whether mine are working as they should please? When I first switched them on (from dry) they ran fast and noisy but once fuel was going through them they were much quieter. That bit I'm happy about, but as they ran up to pressure, they slowed down considerably until they were slowly ticking together. Is that how they should be?
They're running at 7psi at the moment, which is probably a little high, I was thinking that 5psi would be better. Does anyone disagree?
Incidentally, they sound much better than the horrid buzz that the Holley pump made.

Thanks.

Paul

601HP · #84 (**permalink**) 03-09-2014, 03:46 PM

Yours are running as designed. Once line pressure is reached, the pump pulses very slowly. When I test one of my rebuilt pumps, its connected to a flow valve and pressure gauge. With the valve wide open, the pump races. As I dial back the flow by closing down the valve which simulates increased line pressure, the pump slows waayy down! It may pulse once every 0.5 to 1 second.

I'd dial the pressure back to between 5 and 6 psi.

David

FatBoy · #85 (**permalink**) 03-09-2014, 03:55 PM

Hi David,

Thank you for confirming that. I'm please with the end result and now knowing that they are running as they are supposed to is all I needed.

I think I got my rebuild kits from the same place as you. I haven't figured out what the O-rings are for though that came in the rebuild kit.

Paul

601HP · #86 (**permalink**) 03-09-2014, 04:07 PM

Quote:

Originally Posted by FatBoy

Hi David,

Thank you for confirming that. I'm please with the end result and now knowing that they are running as they are supposed to is all I needed.

I think I got my rebuild kits from the same place as you. I haven't figured out what the O-rings are for though that came in the rebuild kit.

Paul

Paul,
I'll take several photos of the O-rings and their location. I'll email you.

David

CSX3183 · #87 (**permalink**) 03-09-2014, 05:36 PM

Yes that is how they operate, and I agree, as to pressure, but if my memory serves me, I ran mine at 7, with no problems what so ever.

Mongoose930 · #88 (**permalink**) 09-03-2014, 07:57 PM

Do you need to put a one way check valve in between the mechanical fuel pump and the SW 240A's so that the electric pumps are not back fed by the mechanical fuel pump? Andrew at GT40 Gold mentioned this is something that should be done but I haven't heard anyone reference that they have put a check valve in.

CompClassics · #89 (**permalink**) 09-03-2014, 08:32 PM

427 = two pumps running at the same time from the same power source, only problem is when one pump shorts to ground and fails (blowing fuse) both pumps fail, even the good one! There was no mechanical pump on the 427 Cobra.

289 street = one mechanical pump.

289 race = one mechanical pump for normal (main) fuel supply, one electrical pump to act as a booster when switching to the secondary (reserve ) fuel supply via the changeover valve located in front of the drivers seat. The mechanical pump will still draw fuel through the electric pump when the electric pump is not activated. The electric pump is only used as a booster pump.

FatBoy · #90 (**permalink**) 09-04-2014, 12:56 AM

Quote:

Originally Posted by CompClassics

427 = two pumps running at the same time from the same power source, only problem is when one pump shorts to ground and fails (blowing fuse) both pumps fail, even the good one! There was no mechanical pump on the 427 Cobra.

All the evidence points to the contrary. There was certainly a mechanical pump fitted to 427 Cobras. What I couldn't say for sure is whether there was an electric pump on road 427 Cobras.
On the Race and S/C cars there was a pair of SW240 pumps connected to a lower pickup in the tank and a mechanical pump connected to a "main" pickup slightly higher in the tank. Two separate fuel lines ran forward and T'd together just beyond the mechanical pump. The electric pumps were only used for priming and reserve with the mechanical pump acting as the sole pump at all other times.
The SW pumps have a none return valve to prevent back flow.

Paul