I don't have any diagrams for the T25 but what I can tell you is that wiring is almost identical on many injection cars (including the T35) the FP relay is directly driven by the ECU but the signal also passes through an inertia switch (in case of crash the FP is stopped!)
You should first check this switch!
On the LHD T35 it's located behind the foot panel on the passenger side (i.e. on the right) behind a little plastic cap. The switch is just under the ECU (its a little black plastic box with a little red push button on top)
I guess you will also find the location described in the driver’s manual.
You should try to reset it and if no improvements check the tension in this area.