How old is the battery, I had a similar problem, my battery was showing 13.2 volts,would turn the engine once the died, battery still showing 12.4, changed it and every thing was fine. It’s not only voltage it’s the amps as well.
When I bought mine, must be more than 20 years ago, he did 2 types, the GTD and original, they are sand bent and have lasted well, as the GTD engine sits higher than SGT I would think not.
I used those on my GTD, they had to be converted to work with the smiths gauges otherwise they showed full when empty, they are sold by Wema here in the U.K., they did the change for me.
The mounting hole on each tank is directly above the bottom of the angle in the tank, different lengths of senders are available and mounting has to be adapted also Wema have to reverse the sender electronics to match the Smiths gauges or they read full when empty and empty when full.
After numerous problems with Smiths senders which use plastic float bearing which seems to be affected by modern petrol because when taken off the tank after a couple of weeks they work fine, I now use Wema fuel level senders converted to work with Smiths gauges, so far fine.
Hi Mark, I'm from Preston, I've got a 347 in mine with 48IDA's dynoed at Tim Adams Racing and produced 429 hip, you're more than welcome to pop round and have a look and chat if you want, tel.01772 743654