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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
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The original fuel pump was an SU, so your customer is moving in the correct direction. In a Jensen-Healey roadster, it would be located in the rear boot, to the left of the fuel tank. I don't know how that might have changed in the Jensen GT since there is no rear boot separate from the hatchback interior.
In the original system, there is a T-fitting a short distance from the pump's output. The main branch goes forward to the carbs, and a T'd-off fuel return line goes to a hose fitting on the tank, near/ a part of the filler neck.
There's a metal restrictor orifice with a 0.046" ID in the return line. With the stock pump, plumbing, and elevation difference between the pump and carbs, the orifice's inside diameter is sized to result in the correct fuel pressure 'at the carb inlets'. It's a 'dumb' fuel pressure regulator. It bleeds off just enough fuel to yield the correct pressure at the carbs. Change anything in the system (like an aftermarket fuel pump) and the pressure at the carb inlets may change.
If a non-standard pump is used, then it's best to eliminate the T-fitting & return line, and cap-off the spigot on the tank's filler neck area. Delete the whole 'dumb regulator', plumb a direct line from the pump outlet to the carb inlets, and install an adjustable pressure regulator as close to the carbs as practical. Set it for 2.5 psi.
I'm sure a JGT owner will chime in with more specifics about the pump's correct location.
Good luck,
Tim Engel
Attachment: JH Fuel Tank, Pump & Plumbing - Factory OEM.jpg (Downloaded 127 times)
Last edited on 10-24-2018 08:25 pm by Esprit2