CDI 174-5721 Guide

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev C •6/19/2023 Page - 1 of 2 QF-358
CDI P/N: 174-5721
This unit replaces the following P/N’s: 855721A 4 and 855721T 8.
Warning! This product is designed to be installed by a professional marine mechanic. CDI Electronics cannot be held liable for
injury or damage resulting from improper installation, abuse, neglect, or misuse of this product.
THIS STATOR IS DESIGNED TO BE USED WITH THE FOUR MAGNET FLYWHEEL. PLEASE VERIFY THAT YOUR FLYWHEEL HAS
FOUR MAGNETS, NOT TWO, WHEN INSTALLING THIS STATOR. IF YOUR FLYWHEEL HAS TWO MAGNETS, THE ENGINE YOU
ARE WORKING ON HAS ONE OF EITHER TWO OLDER DESIGNED IGNITION SYSTEMS AND THIS STATOR WILL NOT FUNCTION
AS DESIGNED!
INSTALLATION
1. Disconnect the Negative battery cable.
2. Disconnect the old Stator from the Switchbox.
3. Remove the flywheel according to the service manual for your engine.
4. Remove the old Stator and save the original bolts.
5. Check for signs of rubbing on the old Stator and the inside of the flywheel.
6. Using the original bolts, install the new Stator with a good thread locker applied to the bolts.
7. Connect the Green/White and White/Green Stator wires to the Switchbox.
8. Reinstall the flywheel according to the service manual for your engine.
9. Reconnect the Negative battery cable.
TROUBLESHOOTING
NO SPARK ON EITHER CYLINDER:
1. Disconnect the Black/Yellow stop wire AT THE SWITCHBOX and retest. If the engine now has spark, the stop circuit has a fault. Check
the key switch and harness.
2. Verify the Flywheel has Four magnets and not Two. The older ignition systems has a Two magnet Flywheel and this Stator will not
work.
3. Inspect and clean all engine and ignition ground connections. Make sure the Switchbox and Ignition coils are grounded properly.
4. Check the cranking RPM. A cranking speed of less than 250 RPM may not allow the system to spark properly. This can be caused by a
weak battery, dragging starter, bad battery cables, or a mechanical problem inside the engine.
5. Check the ignition system resistance and DVA as given below:
Read from Read to OEM Ohms CDI Ohms DVA Connected DVA Disconnected
Green/White (Stator) White/Green (Stator) 370-445 Ω310-385 Ω150 V Minimum 150 V Minimum
White/Green (Stator) Engine Gnd Open Open 150 V Minimum Less than 2 V
Green/White (Stator) Engine Gnd Open Open 150 V Minimum Less than 2 V
Brown/White (#1 Trigger) Brown/Yellow 650-850 Ω650-850 Ω4 V Minimum 4 V Minimum
Green/Yellow (#1 Primary) Engine Gnd - - 150 V Minimum 150 V Minimum
Green (#2 Primary) Engine Gnd - - 150 V Minimum 150 V Minimum
7. Check the DVA on the Black/Yellow kill wire coming out of the Switchbox. You should have a reading of at least 150 DVA or more. The
Stator and Trigger should be connected to the Switchbox for this test. If you do not, check the DVA on the Stator and the Trigger. If the
DVA on the Stator and Trigger is good but the DVA on the Black/Yellow Kill wire coming out of the Switchbox is low, the Switchbox is
likely faulty.
8. Swap the Green/White and White/Green Stator wires and retest. If the problem moves, the Stator is likely faulty.
9. Using a set of jumper wires, cross connect the Brown/White and Brown/Yellow Trigger wires so that you have a Brown/White
connected to a Brown/Yellow. If the problem moves, the Trigger is likely faulty. If the problem stays on the same cylinder, the Switchbox
is likely faulty.
10. Check the flywheel magnets for cracked, broken, or loose magnets.

Installation and Troubleshooting Guide
This installation is to be completed by an Authorized Dealer or Professional Service
Technician. For questions regarding installation or warranty, call CDI Tech Support
at 866-423-4832. Do not return to the Dealer or Distributor where the part was purchased.
Contact CDI Electronics Directly for Return Material Authorization.
CDI Electronics, LLC •353 James Record Road SW •Huntsville, AL 35824 USA
Web Support: www.cdielectronics.com •Tech Support: 1-866-423-4832 •Order Parts: 1-800-467-3371
All rights reserved. Reproduction or use of content, in any manner, without express written permission by CDI Electronics, LLC., is prohibited.
Rev C •6/19/2023 Page - 2 of 2 QF-358
ENGINE WILL NOT STOP (KILL):
1. Check the kill circuit in the Switchbox by using a jumper wire connected to the Black/Yellow wire coming out of the Switchbox and
shorting it to ground. If this kills the engine, the kill circuit in the harness or on the boat is bad, possibly the ignition switch. If this does
not stop the Switchbox from sparking, replace the Switchbox.
HIGH SPEED MISS:
1. Check the DVA of the Stator while running the engine. It should show a smooth climb on the Green/White and Green/White Stator
wires. If there is a sudden or fast drop in voltage right before the miss becomes apparent, the Stator is usually at fault.
2. Perform a high-speed shutdown and read the spark plugs. Check for water. A crack in the block can cause a miss at high speed when
the water pressure gets high, but a normal shutdown will mask the problem because the water will evaporate off the spark plug before
you can identify it.
BOTH CYLINDERS HAVE SPARK BUT THE ENGINE WILL NOT RUN:
1. Check the flywheel shear key.
2. Index the flywheel and check timing on both cylinders. If the timing is off, check the Trigger and flywheel center hub Trigger magnet.
WILL NOT ACCELERATE BEYOND 3000-4000 RPM:
1. Connect a DVA meter between the Stator’s Green/White and White/Green wires. Run the engine up to the RPM where the problem is
occurring. The DVA should show a smooth climb in voltage and remain high through the RPM range. A sharp drop in DVA right before
the problem occurs usually indicates a bad Stator.
2. Connect an inductive tachometer to each cylinder in turn and try to isolate the problem. A single cylinder dropping spark will likely be a
bad Switchbox or Ignition coil. All cylinders not sparking properly usually indicates a bad Stator.
3. Check the flywheel magnets for cracked, broken, or loose magnets.
MISS AT ANY RPM:
1. In the water or on a Dynamometer, check the DVA on the Green and Green/Yellow Primary wires from the Switchbox while connected
to the Ignition coils. You should have a reading of at least 150 DVA or more, increasing with engine RPM until it reaches 300-400 DVA
maximum. A sharp drop in DVA right before the miss becomes apparent on all cylinders will normally be caused by a bad Stator. A
sharp drop in DVA on less than all cylinders will normally be the Switchbox or Trigger.
2. Connect an inductive tachometer to each cylinder in turn and try to isolate the problem. A high variance in RPM on one cylinder usually
indicates a problem in the Switchbox or Ignition coil. Occasionally a Trigger will cause this same problem. Check the Trigger DVA (see
NO SPARK ON EITHER CYLINDER).
3. Check the flywheel magnets for cracked, broken, or loose magnets.
SWITCHBOX REPEATEDLY BLOWS ON SAME CYLINDER:
1. Check the Trigger wires for shorts to engine ground as a shorted Trigger wire can destroy a SCR inside the Switchbox.
2. Replace the Ignition coil on the cylinder dropping spark.