It's not a sensor, or the HP pump.
The ONLY thing moving when you turn the ignition on is the lift pump pressuring the LP side of system. It's that causing the issue, either the pump itself dying, which is possible due to the gold flakes, high milage and cutting out, or the fuel lines themselves as my above post. When you found the gold filings, I take it you cleaned the filter housing and everything well?
Also, this isn't an MOT fail.... It's not a safety issue, so there's nothing to worry about there.
The ONLY thing moving when you turn the ignition on is the lift pump pressuring the LP side of system. It's that causing the issue, either the pump itself dying, which is possible due to the gold flakes, high milage and cutting out, or the fuel lines themselves as my above post. When you found the gold filings, I take it you cleaned the filter housing and everything well?
Also, this isn't an MOT fail.... It's not a safety issue, so there's nothing to worry about there.