Regulator and Fuel Pump Testing, plus wiring routes

[SteveW]

Having finally found some time to work on my TC, the scuttle is now repaired, painted and fitted so I'm ready to start to do all of the wiring and plumbing that fit to it.

Is there a way to test the fuel pump and also the regulator off the car before I fit them.

Also, does anyone have a picture of where the wiring runs on the inside of the scuttle on it's way to the dashboard?

Steve

[rstarkweather]

Steve:

Check the Tech Info tab on the "From the Frame Up" web site. The Tech Tips section has an entry for Under Dash Wiring and Control Cables. Should be helpful.

Rick

[Tom Lange, MGT Repair]

If I remember right, it should take 45 seconds to pump a pint of fuel by an SU fuel pump. That works out to 1.3 pints per minute. You can run the pump in situ, even without the e3ngine in place, to test.

Points do need the occasional cleaning, but often the diaphragm gets hard, and nothing short of rebuilding will fix that.

Tom Lange
MGT Repair

[Duncan M]

Fitting a bi-directional transil inside the fuel pump will extend its life dramatically, and render it positive or negative ground. With fresh points and a transil, they will easily outlast the life of a new diaphragm and require no maintenance to the points. https://ttypes.org/extend-the-life-of-y ... a-transil/ Remove the cap on a pump some time and run it on a 12 volt source. The amount of sparking without a transil is nuts. With the transil, the sparking is resaonable.

Only way to fine tune a functional regulator is to run it and make fine adjustments as needed. Either the battery will overcharge (easily checked) or it will undercharge, which is also easily checked--during use of the car. Your driving style will influence how it should be adjusted, to some extent.

[Rob Reilly]

Thanks, I couldn't remember that part name transil.

There are several videos on Youtube about rebuilding and testing the low pressure SU fuel pumps. Operationally they are all pretty much the same, just different sizes, pump body designs and external fittings.

I've rebuilt about a dozen with new diaphragms from Moss or Burlens or SU Rebuilders, and always convert them to transistor operation. As I recall the origin of the transistor design was some MGT folks some 40 years ago. Be aware there are two different lengths on the diaphragm shaft.

20230927_094900.jpg (46.37 KiB) Viewed 1091 times

A guy named Marek in the UK makes the circuit boards.
https://forums.jag-lovers.com/t/su-fuel ... e/388427/2

On the regulator, first clean the contact points and all riveted electrical connections, that's where the corrosion gets them. I used muriatic acid swimming pool cleaner and then a good rinse with water.

[SteveW]

Thanks for the advice. I'll give all that a go and report back on how I get on.