Check the following:

That the pickup connection is OK.

Check for possible Points bounce, float or poor ignition grounding.

Check Tachometer ground is the same as ignition system.

Intermittent supply wiring to tacho. Check the 9w Pins & sockets for dirt -check sockets for damage or if opened out.

Coil requires RFI suppression capacitor - fit RFI suppression capacitor.

Battery failing under vibration or load - replace battery with known good unit.

Internal memory failure - return to STACK.

System configured with wrong number of targets per wheel revolution:

Reconfigure the system with correct values.

System configured with the wrong wheel circumference

Reconfigure the system with correct values.

Typical wheel circumference is 1800mm (70 inches) for a car or
900mm (35 inches) for a kart

Interference from ignition system and HT leads:

Fit suppressed (Silicon) HT Leads. Fit a suppression capacitor (2.2uF) between
the coil (battery connection) and chassis.

Check the capacitor on the distributor points system - fit a new capacitor if necessary.

Use "Helical" suppressed leads in extreme cases.

ST700 Dash Display System wiring is too close to the HT leads and/
or injector leads, or the HT leads are tied to isolated metal work to
which the system wiring is also tied.

Run wiring away from HT leads and injector leads

Recommended minimum spacing is 75mm (3.0 inches)

You can restore the ST700 Dash Display System to its factory settings
by pressing the Driver button and the Rotary control together, and then switching on the ignition. This also clears the lap and split timings, and resets all the peak readings.

After you restore the factory settings, the Demonstration Mode will be activated. To turn off the Demonstration Mode, set the correct number of cylinders as instructed on page 53 of the manual.

It is not permissible to connect a second gauge -

Disconnect other gauge

System configured with wrong number
of engine cylinders - reconfigure system
to correct number of cylinders.

Ignition system pulses per revolution not same as number of cylinders - Reconfigure system
to correct number of pulses per revolution.

Note: Ignition systems may either: a) produce "waste" sparks giving double the number of cylinders per revolution b) use multiple coils where each additional coil gives proportionately fewer pulses per revolution.

Ensure alarms are switched on. Reset the RPM gate to a lower value - alarms only operate when the engine is running at the RPM gate value or above it.

The “Re-Scan” button was clicked on the Program Setup tab. Click the “Read Config” button. If that doesn’t work, Exit the Configuration Utility and restart it.

Sensor failure - Disconnect Sensor if systems shows shows “0” replace sensor.

Faulty connectors - Check continuity of
leads for short.

Sensor failure - Disconnect and short connectors together. If reading changes replace sensor.

Faulty connectors - Check continuity of
leads for open circuit.

Switch(es) faulty - contact a Stack service agent, no user serviceable parts.

Manual Lap Time Switch faulty - replace switch. Disconnect the switch and short its leads together. If a lap pops up, replace the switch. Otherwise check wiring.

Faulty switch wiring - check switch wiring for correct continuity Pin T to pin 1 of the LAP connector greater than 1.0 Ohm and Pin T to Pin H (earth) greater than 1M Ohms

System configured with wrong number
of engine cylinders - reconfigure system
to correct number of cylinders.

Ignition system pulses per revolution not same as number of cylinders - Reconfigure system
to correct number of pulses per revolution.

Note: Ignition systems may either: a) produce "waste" sparks giving double the number of cylinders per revolution b) use multiple coils where each additional coil gives proportionately fewer pulses per revolution.

Faulty sensor and/or wiring - check sensor indicator for correct operation.

Incorrect sensor gap (too far or too close) - check that the gap is approximately 1mm.

Sensor and targets moving apart - fabricate a more rigid sensor bracket.

Note: Rotate the wheel by hand and check that the sensor indicator lights up as each target passes the sensor