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Appendix A Troubleshooting Guide
The troubleshooting chart on the following pages should help determine and rectify most problems with your installed NOS
system. If you still need assistance determining or fixing problems, call the NOS Technical Support at 1-866-GOHOLLEY.
PROBLEM
POSSIBLE CAUSES
DIAGNOSTIC PROCEDURE
CORRECTIVE ACTION
Bottle valve not fully opened.
Check bottle valve.
Open valve fully.
Plugged nitrous filter.
Inspect filter.
Clean/replace filter.
Low bottle pressure.
Check bottle temperature.
Set bottle temperature to 80°
to 85°F.
Inadequate nitrous supply.
Weigh bottle.
Fill bottle. 1-800-99-REFILL
Excessive fuel pressure.
Measure the pressure during
acceleration with the nitrous
operating.
Regulate pressure down.
Loose nitrous solenoid
wiring.
Inspect the solenoid wiring.
Repair wiring.
Engine runs rich when
system is activated.
Malfunctioning nitrous
solenoid.
Disconnect the solenoid wires
from the blue relay. Connect the
12V test light to the battery (-).
Turn the arming switch ON.
Manually set the microswitch ON.
Use the test light probe to check
for power at the solenoid.
Replace the solenoid.
*Below 70°F ambient, NOS
Bottle Heater #14164 is
recommended to maximize
performance.
Bottle valve closed.
Check bottle valve.
Open valve fully.
In-line fuse blown
Check fuse.
Replace fuse.
Plugged nitrous filter.
Inspect filter.
Clean/replace filter.
System wired incorrectly.
Compare nitrous wiring to
schematic (Figure 7).
Wire system per instructions.
Loose ground wire(s).
Connect 12V test light to battery
(+) terminal. Check for continuity
at grounds shown in Figure 9.
Tighten/repair loose
ground(s).
Malfunctioning arming
switch.
Turn arming switch ON. Connect
12V test light to battery (-)
terminal. Check for power at red
wire on power relay switch.
Replace arming switch.
No change in performance
when system is activated.
Malfunctioning throttle
microswitch.
Temporarily disconnect power
relay green wire from microswitch.
Connect 12V test light to battery
(+) terminal. Manually set the
microswitch ON. Check for
continuity at open terminal of
microswitch (Figure 9).
Replace throttle microswitch.
Excessive ignition timing.
Check ignition timing.
Set timing to factory settings.
Inadequate octane fuel.
Use higher octane fuel.
Spark plug heat range too
high.
Reduce spark plug heat
range (max. 2 steps).
Engine detonates mildly
when system is activated.
Too much nitrous flow.
Reduce nitrous jetting.
Inadequate fuel delivery due
to: Plugged fuel filter.
Inspect fuel filter.
Clean or replace fuel filter.
Crimped fuel line.
Inspect fuel line.
Replace crimped line.
Engine detonates heavily
when system is activated.
Weak fuel pump.
Install fuel pressure gauge, such
as NOS P/N 15931. Run engine
under load at wide-open throttle,
with system activated.
Repair/replace fuel pump.
Excessive spark plug gap.
Inspect spark plugs.
Set spark plug gap at 0.030
to 0.035”
High-RPM misfire when
system is activated.
Weak ignition/ignition
component failure.
Inspect components (plug wires,
distributor cap, etc.)
Replace worn components.
Inadequate supply of
nitrous.
Check bottle weight.
Replace bottle.
Surges under acceleration
when system is activated.
Bottle mounted incorrectly.
Compare bottle position and
orientation to instructions.
Mount or orient bottle
correctly.
