Yamaha F15A / F9.9C / FT9.9D (1998, 323 cm³) service guide
Oil, gear oil, spark plugs and the service schedule for the Yamaha F15A / F9.9C / FT9.9D (1998, 323 cm³) (9.9 to 15 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: Four-stroke 2 cylinder OHC, 323 cm³, 59.0 x 59.0 mm, one carburetor, CDI. A different engine from the later F15C/F20 (6AG/6AH, 63.0 x 58.1 mm). F15A model code 66M (F15AMH = F15MSHX/F15MLHX, F15AEH = F15ESHX/F15ELHX, F15AE); F9.9C model code 66N (F9.9CMH, CEH, CE); FT9.9D model code 66R (FT9.9DMH, DEH, DE).
Quick answers
- How much oil does a Yamaha F15A / F9.9C / FT9.9D take?
- 1,200 cm³ (40.6 US oz, 42.2 Imp oz) with filter; 1,000 cm³ (33.8 US oz, 35.2 Imp oz) without filter.
- What engine oil does a Yamaha F15A / F9.9C / FT9.9D use?
- 4-stroke engine oil, API SE, SF, SG or SH, SAE 10W-30, 10W-40 or 20W-40.
- What gear oil does a Yamaha F15A / F9.9C / FT9.9D use, and how much?
- Hypoid gear oil, SAE #90. Quantity: F15A and F9.9C 250 cm³ (8.45 US oz, 8.80 Imp oz); FT9.9D 320 cm³ (10.81 US oz, 11.27 Imp oz).
- What spark plug does a Yamaha F15A / F9.9C / FT9.9D use?
- DPR6EA-9. Gap: 0.9 mm (0.04 in).
- How often should a Yamaha F15A / F9.9C / FT9.9D be serviced?
- The factory schedule lists: Initial 10 hours; 50 hours (3 months); Every 100 hours (6 months); Every 200 hours (1 year). In Hawaiʻi's salt water we do a full yearly service every 200 hours or 1 year, whichever comes first, and a new engine needs its first (break-in) service.
- When should the water pump impeller be replaced on a Yamaha F15A / F9.9C / FT9.9D?
- The factory schedule says to inspect it at 100 hours and 200 hours. In Hawaiʻi's warm salt water we replace it every 200 hours or 1 year, whichever comes first, because a worn impeller is the most common cause of overheating.
- What is the idle speed of a Yamaha F15A / F9.9C / FT9.9D?
- F15A 950 ± 50 r/min (trolling 850 ± 50); F9.9C 950 ± 50 (trolling 850 ± 50); FT9.9D 1,050 ± 50 (trolling 950 ± 50).
- What is the propeller nut torque on a Yamaha F15A / F9.9C / FT9.9D?
- 17 N·m (1.7 m·kg).
Maintenance specs
| Engine oil | 4-stroke engine oil, API SE, SF, SG or SH, SAE 10W-30, 10W-40 or 20W-40 |
|---|---|
| Engine oil quantity | 1,200 cm³ (40.6 US oz, 42.2 Imp oz) with filter; 1,000 cm³ (33.8 US oz, 35.2 Imp oz) without filter |
| Oil filter | 18 N·m (1.8 m·kg, 13 ft·lb); oil filter plug in the cylinder block (M20) 40 N·m (4.0 m·kg, 29 ft·lb) |
| Engine oil drain plug (M14) | 27 N·m (2.7 m·kg, 19.5 ft·lb) |
| Gear oil | Hypoid gear oil, SAE #90 |
| Gear oil quantity | F15A and F9.9C 250 cm³ (8.45 US oz, 8.80 Imp oz); FT9.9D 320 cm³ (10.81 US oz, 11.27 Imp oz) |
| Lower unit holding pressure | 100 kPa (1.0 kg/cm², 14.2 psi) |
| Spark plug | DPR6EA-9 |
| Spark plug gap | 0.9 mm (0.04 in) |
| Spark plug torque | 18 N·m (1.8 m·kg, 13 ft·lb) |
| Idle speed | F15A 950 ± 50 r/min (trolling 850 ± 50); F9.9C 950 ± 50 (trolling 850 ± 50); FT9.9D 1,050 ± 50 (trolling 950 ± 50) |
| Thermostat | Opens 58 to 62 °C (136.4 to 143.6 °F); fully open 70 °C (158 °F); lift 3 mm (0.12 in) |
| Anode mounting bolt (M5) | 5 N·m (0.5 m·kg, 3.6 ft·lb) |
| Propeller nut (M10) | 17 N·m (1.7 m·kg) |
| Valve clearance, cold | Intake 0.20 ± 0.05 mm (0.008 ± 0.002 in); exhaust 0.25 ± 0.05 mm (0.010 ± 0.002 in); valve adjusting screw 14 N·m (1.4 m·kg, 10.0 ft·lb) |
| Timing belt | Slack 0 to 10 mm (0 to 0.4 in); inspect/replace every 100 hours |
Service schedule
The factory maintenance intervals, with what is replaced and what is checked at each. Rows marked Hawaiʻi are our shop's yearly service for salt water use.
Initial 10 hours
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets
Check: spark plugs, fuel filter
50 hours (3 months)
Replace: gear case plug gaskets, propeller cotter pin
Check: spark plugs, fuel filter, anodes
Every 100 hours (6 months)
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin
Check: spark plugs, fuel filter, water pump impeller, anodes
Every 200 hours (1 year)
Replace: engine oil, oil filter, oil drain plug gasket, gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller
Check: spark plugs, fuel filter, thermostat, anodes
We replace the water pump impeller at every service from 200 hours up, which can be sooner than the factory schedule, because of Hawaiʻi’s warm salt water.
Source: Yamaha F15A, F9.9C, FT9.9D service manual. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.