Dear customer, sorry for the delay.
The sambar model like yours have a shared loom under the rod of the steering wheel.
I want to explain, this problem is a short evident in the circuit, it happens that the electric circuit of your truck shares the directionals, the turn signals, the lights of the headlights, the suiche etc. and if there are shorts in this one you can effectively cancel the signal of the fuel pump or the coil.
Keep in mind that your vehicle is 25 years old, it is common that moisture, heat and other factors damage the vehicle's electrical system, detecting this fault with precision when the wire loom or wiring is fitted to the car is very difficult.
My recommendation in your case is to disarm all the wiring, it is a tedious but necessary work, all kinds of damage that you observe repair it, from a small peeling in the wiring to a mator damage like a burnt or split, but it is better to have all the wiring out of the vehicle and to have visual access to the whole wiring, review wire by wire being still instaled in the car is very difficult, that is a common problem that appears in the Sambar.
Have you understood me dear customer?