Mitsubishi Triton Pricing and Specs

This sounds like a case of a split fuel pick-up pipe in the fuel tank. When the tank is full, the split in the pick-up is covered by fuel, so the pump works normally at supplying the injectors with fuel. But when the level in the tank falls, the split is exposed and the fuel pump suddenly finds it’s much easier to suck air rather than fuel. And engines don’t run too well on just air.

This could be interpreted by a scan-tool as a fuel leak, so a check of the tank’s pick-up tube seems like a good place to start looking. Any actual fuel leak large enough to cause this problem would, presumably, be visible, but it’s worth a check of the fuel rail and return lines as well. Failing that, you could have a dud sensor that is telling the computer there’s a fuel shortage and sending the car into limp-home mode to protect the engine (which would also explain the loss of power). It would also be worth checking to see that the new Suction Control Valve (SCV) is working properly, even though it's brand new.

If you had a loss of drive in every gear, the suspicion would be that the transmission is low on fluid or the torque converter is not working properly. But if it’s only reverse gear that is playing up, the chances are that the bands or clutch pack that locks the transmission into Reverse is allowing the gears inside the transmission to spin without actually transferring torque to the output shaft (and thence to the wheels).

That said, there could be other internal problems that could cause this, so a visit to a transmission specialist is the best advice. Don’t delay it either, as continuing to drive the vehicle in its current state could do more damage to the transmission.

Diagnosing electrical problems remotely is a hiding to nowhere, but conventional wisdom says the wiring, earths and related switches are the first place to start. But modern vehicles also rely on body computers to control some of these functions, so that's worth a check, too.

I can only hope you raised and logged this issue with Mitsubishi when it first started happening. If you did, you have what's called a pre-existing condition under the factory warranty terms. If the problem first surfaced five years ago, that would place the flickering occurring from about 2019. Which means, as a 2018 vehicle, it would have been covered by the Mitsubishi warranty. Even if the car subsequently runs out of warranty, a pre-existing condition is still legally required to be fixed by the car's manufacturer.