TA-TC fuel pump pressure

[bergxu]

Hi gents,

Waking up my TA it seems the pump won’t pull fuel from the tank despite lots of ticking and the fact that fuel will flow if I put a vacuum on the line so I know it’s not a clog or other feed issue. Wondering if anyone can advise on the pressure the pump generates as I’d like to see if I can find one of the German made Hardi pumps to go in place of the original SU. Otherwise I’ll redo the original pump and for a transil whilst in there.

Cheers,
Aaron

[Will]

Have you considered two pumps? One always on stand-by.
One pump under the tank and the other the original SU connected with a center off left/right toggle switch.
Many pumps will push fuel through the SU. And the SU will still draw fuel through the stand-by.
These pumps are quiet, https://simonbbc.com/categories/fuel-fuelling.html. Fuel Flow FF105 1-4psi.
If you install one you could bypass (with a hose) your SU while you rebuild it.

[johnnie.w]

Facet fuel pump mounted near the tank keeps the fuel line cool , a pressure regulator to keep the pressure at about 2 to 3 psi works for me

[Rob Reilly]

What is the status of your original pump? Unrestored original? Restored by some unknown person? Restored by you?
There should be two discs inside that are basically check valves to stop flow backwards. Be sure they are clean and seal reasonably well.
I have found that when they are dry inside they won't pull up the fuel from an empty tank line that is lower than the pump. Try priming the pump with a bit of fuel in the top fitting.
The pressure is low, around 2 or 3 psi or so. You really don't need pressure, what you want is flow rate in so many pints per minute. The SU pump should be able to do it.
There are several electronic conversion schemes around, and the transil is the latest. I have been happy with the one that adds a transistor, diode and resistors. It is made by a Jaguar owner named Marek in England.

20230927_094900.jpg (46.37 KiB) Viewed 982 times

https://forums.jag-lovers.com/t/su-fuel ... ade/388427

[Steve Simmons]

The puller type pumps (AUA25) are 1.5 psi. The later pusher type for TF, MGA/B, etc are higher, between 2.7 and 3.8 IIRC.

[bergxu]

Thanks all,

I do not know the history of the fuel pump. It’s an older SU which I’m sure has been replaced at some point in the past. I’m happy to do an overhaul of the existing pump but I guess I need to identify if it’s a pre or post 1985 manufacture so I can get the correct kit.

I did try and prime the pump with some fuel as I know they can lose prime when they sit but that only got the car running long enough to burn the fuel that I force fed it so I think it’s rebuild or replacement time. I’d prefer to rebuild and add a transil but I’m in a bit of a time crunch as I’m moving all of my cars from my old building to a new one so I’d like to get the car running quickly so I can load it onto my trailer for the move.

[Steve Simmons]

Worst case, if you fill the float bowls with fuel then it should give you plenty of runtime to get it onto a trailer.

[bergxu]

Worst case, if you fill the float bowls with fuel then it should give you plenty of runtime to get it onto a trailer.

Good point.

[Rob Reilly]

Likely it needs a new diaphragm and points. There are long and short stem diaphragms so measure your coil body length to get the right one. The original pump was the longer length. Moss has all 4 varieties.