PROBLEM 1: ENGINE IDLES ROUGH AND
STALLS
Possible Cause Corrective Action
PROBLEM 2: ENGINE RUNS ENEVEN OR
SURGES
PROBLEM 3: ENGINE WILL NOT ACCELERATE.
A crack in the fuel outlet
tube (located in fuel
tank.)
Replace.
Anti-Siphon valve re-
stricting fuel flow.
Refer to “Checking for
Restricted Fuel Flow
Caused by Anti-Si-
phon Valves,” follow-
ing.
PROBLEM : FUEL BLOW-BACK OUT OF CAR-
BURETOR
PROBLEM : CAN’T REDUCE ENGINE RPM TO
SLOW IDLE
PROBLEM : ROUGH IDLE
Possible Cause Corrective Action
Chipped/Broken (reed-
block) Reeds
Replace Reeds.
If related to reed-block,
indicates excessive
preload in reeds.
Replace Reeds.
Multiple chipped reeds Replace Reeds.
3A-10 - FUEL SYSTEMS 90-817643R1 DECEMBER 1996
CHECKING FOR RESTRICTED FUEL FLOW CAUSED
BY ANTI-SIPHON VALVES
While anti-siphon valves are helpful from a safety stand-
point, they clog, they may be too small, or they may have
too heavy a spring. The pressure drop across these valves
can, create operational problems and/or powerhead dam-
age by restricting fuel. Some symptoms of restricted (lean)
fuel flow, are:
1- Loss of fuel pump pressure
2- Loss of power
3- High speed surging
4- Preignition/detonation (piston dome erosion)
5- Outboard cuts out or hesitates upon acceleration
6- Outboard runs rough
7- Outboard quits and cannot be restarted
8- Outboard will not start
9- Vapor lock
Any type of anti-siphon device must be located between
the outboard fuel inlet and fuel tank outlet. A method of
checking [if such a device (or bad fuel) is a problem source]
is to operate the outboard with a separate fuel supply which
is know to be good.
If, it is found that the anti-siphon valve is the cause of the
problem, either 1) replace the anti-siphon valve or 2) re-
place it with a solenoid-operated fuel shutoff valve.
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