High Altitude Re-Jetting - MerCruiser GM4 Service Manual

High Altitude Re-Jetting

Engine flooding problems, at idle RPM, are generally related to the altitude (above sea level) at which they are
operated. If engine is running too rich at higher elevation, order a smaller jet from the chart. A jet stamped "165"
is a 1.65 mm jet.
Model
3.0L
3.0L/3.0LX
3.0LX
JET SIZES
Jet Size
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
1.70
1.75
1.80
1.85
1.90
Index
90-816462 2-695
Carburetor Part 500 Ft. (1525 m)
Number
1389-9562
1.45 mm Stock Jets
3310-806077
1389-815396
3310-806078
3310-805924
1389-815397
Quicksilver Part
Number
3302-811849
3302-811850
3302-811851
3302-9050
3302-811852
3302-811853
3302810923
3302-9058
3302-9055
3302-881854
3302-811855
3302-811856
3302-811857
5000-9000 Ft.
and Below (1525-2745 m)
1.40 mm
1.60 mm 1.50 mm
1.65 mm 1.55 mm
9000 (2745 m)
and Above
1.35 mm
1.45 mm
1.50 mm
MERCARB 2 BARREL CARBURETOR - 5B - 3