Sierra Mercruiser Voltage Regulator

Sierra 18-99421 MerCruiser Voltage Regulator Replaces CDI 194-9502

This Sierra voltage regulator is for use with MerCruiser electrical systems.

Sierra 18-99421 Voltage Regulator Application Information

Fits: 470 w/2 BBL Carb from 1976-1984

Fits: 485 & 488 w/ 2 BBL Carb from 1980-1984

Fits: 170 & 190 from 1985-1986

Fits: 165 & 180 from 1987

Fits: 3.7L from 1988-1989

Interchangeable With:

CDI

194-9502

Mercury

77305A2

86255A2

86255A3

99502A12

99502A13

99502A7

99502A8

99502A9

Click here for Sierra 18-99421 Voltage Regulator Installation Instructions

Frequently Asked Questions

• What is the Sierra 18-99421 MerCruiser Voltage Regulator used for? The Sierra 18-99421 MerCruiser Voltage Regulator is a replacement voltage regulator designed for use with MerCruiser electrical systems. It is listed for specific MerCruiser engine applications ranging from 1976 through 1989, depending on the engine model and configuration.
• What MerCruiser engines does the Sierra 18-99421 Voltage Regulator fit? The Sierra 18-99421 fits 470 engines with 2 BBL carburetors from 1976-1984, 485 and 488 engines with 2 BBL carburetors from 1980-1984, 170 and 190 engines from 1985-1986, 165 and 180 engines from 1987, and 3.7L engines from 1988-1989.
• Does the Sierra 18-99421 replace CDI 194-9502? Yes. The Sierra 18-99421 Voltage Regulator is listed as interchangeable with CDI 194-9502. This replacement reference can help when comparing the existing voltage regulator or part number before ordering.
• What Mercury part numbers are interchangeable with the Sierra 18-99421? The Sierra 18-99421 is interchangeable with Mercury 77305A2, 86255A2, 86255A3, 99502A12, 99502A13, 99502A7, 99502A8, and 99502A9. Compare your existing part number and verify the specific engine application before ordering.
• Is the Sierra 18-99421 compatible with MerCruiser 3.7L engines? Yes. The application information lists the Sierra 18-99421 for MerCruiser 3.7L engines from 1988-1989. Confirm your engine model and year against the listed application information before using this voltage regulator.
• What should I verify before ordering the Sierra 18-99421 Voltage Regulator? Verify your MerCruiser engine model, year, and configuration against the listed applications. For the 470, 485, and 488 applications, also confirm the 2 BBL carburetor configuration. Comparing the existing regulator's part number with the listed CDI and Mercury references can provide an additional fitment check.