Specifications

Mercury MerCruiser Engine Emission Regulations Changes Effective
January 1, 2003.
The changes that become effective January 1, 2003, regarding emission regulations, pertain to
all Mercury MerCruiser gas Sterndrives, Inboards and Tow Sports models, as well as the
Scorpion 377 and HP500 EFI Racing Sterndrive (hereafter referred to as MerCruiser engines)
certified to California emissions standards.
All MerCruiser engines (500 hp and below) with a production date of January 1, 2003, or later
are factory-certified to meet the California Air Resources Board’s (CARB) 2003 exhaust
emission standards. Each factory-certified engine includes a Consumer Information Hang Tag
and two California three-star labels, one on the engine and one with instructions for proper
installation by the boat builder on MerCruiser-powered boats. The star label is required by the
State of California to be affixed to the hull per their guidelines.
Dealers in CA, AZ, NV and OR received further information found below:
Please note that MerCruiser engines built prior to January 1, 2003 do not require CARB
certification and may be sold without restriction. Specifically, MerCruiser engines in your
inventory that were built prior to the effective date do not require certification (three-star label)
and may be sold in California. Also note that the HP900 SC Dry-Sump, HP575 SCi and the
HP525 EFI Mercury Racing Sterndrive engines do not require certification and may be sold in
California.
The length of warranty coverage on certain components considered as emissions related
components by California CARB certification is also different.
All carburetors on 3.0L, 4.3L, 5.0L and 5.7L engines, boxed after 1.Jan 2003, have a sealed idle
mixture screw.
The idle mixture screw adjustment is strictly regulated by CARB. However, if the carburetor is
overhauled, CARB allows the adjustment of the mixture screw back to original specifications.
The idle mixture screw is located under the sealed cap. After the overhaul, install a new Tamper
Proof Idle Mixture Screw Kit, leaving the cap off. Adjust the idle mixture screw back to the
original factory specified 'turns out' (see reference list below), then install the tamper proof
sealing cap.
NOTE: Access to the idle mixture screw can only be made by removing the seal. The sealing
cap can be removed by carefully cutting both sides of the outer seal. Use a screwdriver to pry
the outer seal apart at the cuts until you can get the cap out. It is recommended that additional
Tamper Proof Idle Mixture Screw Kits be ordered for stock because the original seal will be
damaged during the removal process.
P/N 3302-803930 Tamper Proof Idle Mixture Screw Kit. (Kit includes a new idle mixture screw,
spring, seal cup and seal cap).
3.0L: P/N 3310-864940A01 w/sealed idle mixture screw: Screw set at 1-1/2 turns out.
4.3L: P/N 3310-864941A01 w/sealed idle mixture screw: Screw set at 1-1/4 turns out.
5.0L: P/N 3310-864942A01 w/sealed idle mixture screw: Screw set at 1-1/2 turns out.
5.7L: P/N 3310-864943A01 w/sealed idle mixture screw: Screw set at 1-1/2 turns out.
NOTE: The carburetor P/N listed is the complete replacement service carburetor that must be
used on engines built after January 1, 2003.