Hello friends,
Would someone be able to tell me what the ideal fuel pressure ought to be for a standard set up 3.4L 1961 MK2, please? The carburettors are in good order and have the mixtures accurately set. I have fitted a new SU electronic fuel pump which was recommended for the car by the SU distributor in Australia.
Cheers,
Tim
No more than 4 psi …
The V12 carburetter cars, series3 E and series1 XJ, have recirculating fuel systems
incorporating a simple spring and ball pressure regulator set at 2 / 21/2 lbs psi.
Should be enough for a 3-4.
Peter B.
Thank you for that information, Robin, most helpful.
Cheers,
Tim
Don’t forget to put a filter BEFORE the pump. A see through disposable one will show you what can land in your fuel tank.
Gerard
Hi Gerard,
I have one of those now. When I bought the car I discovered one after the pump which was more or less fully blocked! After I replaced it the pump’s diaphragm collapsed and filled the boot with fuel. Now the carburettors are receiving fuel at a better pressure, they crying out for some attention. And just to top it all off, the 12v charging system is playing up. It could be the generator or voltage regulator. There’s always something!
Tim
What is your battery voltage with the engine off. Voltage at the battery when running and voltage directly off of the generator terminals when running.
Gerard
Hello all,
Just to follow up on the charging issue. The battery went flat because the original radio decided to work after thirty years and I hadn’t realised it was in the “on” position! So it very quietly drained the battery. Anyway, I now have a fully charged battery and a radio which works! Now, what to do about the oil leaks?
Cheers,
Tim
Thicker oil 
…
Perhaps drain the oil altogether!
Problem goes away.
Tim
About a year ago I measured my 3.4 ltr S type fuel pressure. As you may be aware the S type has a slightly different fuel system and twin pumps, but the same carbs as the Mk 2, At the time the engine had been rebuilt and carbs overalled, the pumps were electronic and the test gauge was certified.
Fuel pressure under running conditions was 3.1 lbs on one pump and 3.2 lbs on the other.