Air Intake System
90-863758060 AUGUST 2006
Page 4A-5
Interpreting Results
Changes must be made to the fuel system or ventilation system if the readings fall outside
of the specifications or the engine bogs or stalls under hard acceleration. Potential causes
may be:
Condition
Symptom
Hesitation
The throttle is opened and there is a 1–2 second hesitation before the engine responds
and possibly a backfire. Some hesitation is acceptable in moderate to extreme
conditions.
Stumble
The engine accelerates and drops 200–1000 RPM for a moment and then recovers.
Backfire may occur. Some stumble is acceptable in extreme conditions.
Bog
Much more severe than a stumble. The engine drops over 2000 RPM after acceleration
for 10 or more seconds. Backfire may occur. The engine barely recovers.
Stall
The engine ceases to run or fails to start.
Excessive engine compartment temperature or pressure differential
•
Insufficient cross-sectional area of air vents and related hardware.
•
Inlet and exhaust vents improperly located on boat (too close to one another, both in
high pressure or low pressure areas).
•
Vent hoses too restrictive (excessive bends, too small, laying in water).
•
Vent hoses not positioned to allow good circulation of air.
•
A blower may be required to get proper ventilation.
Excessive Fuel Inlet Temperature
•
Same as above.
•
Too much of fuel tank, lines, and related hardware exposed to engine compartment–
reduce or insulate.
•
Fuel line located too high in engine compartment (warmest air is at top of compartment).
•
Fuel line too close to hot surface on engine.
•
Refer to
Section 5—Fuel System
for more information.
Excessive Fuel Pressure Drop
•
Fuel system excessively restrictive (lines too small, too many fittings).
•
Auxiliary fuel filter utilized.
•
Anti-siphon valve too restrictive.
•
Refer to
Section 5—Fuel System
for more information.
Everything Within Specifications, But Engine Still Hesitates, Stumbles, Bogs, or
Stalls
.
•
RVP of fuel too high.
Summary of Contents for 8.1S Horizon
Page 5: ...Page iv...
Page 19: ...Important Information Notes Page 1A 14 90 863758060 AUGUST 2006...
Page 53: ...Transmission and Drive Line Notes Page 2A 14 90 863758060 AUGUST 2006...
Page 59: ...Air Intake System Notes Page 4A 6 90 863758060 AUGUST 2006...
Page 119: ...Cooling System Notes Page 7A 22 90 863758060 AUGUST 2006...
Page 133: ...Electrical System Notes Page 8A 14 90 863758060 AUGUST 2006...
Page 153: ...Instrumentation and Controls Notes Page 9A 20 90 863758060 AUGUST 2006...
Page 163: ...Predelivery Preparation Notes Page 10A 10 90 863758060 AUGUST 2006...
