GMC 1994 Yukon Owner's Manual page 253

Water
in
Fuel
Sometimes, water can be pumped into your fuel tank along with your diesel
fuel. This can happen if a service station doesn't regularly inspect and clean
its fuel tanks, or if it gets contaminated fuel from its suppliers.
If this happens, a "WATER IN FUEL" light will come on. If it does, the
excess water must be drained. Your dealer can do this for you.
This light also should come on briefly when you start your engine, as a
check. If it doesn't, have it fixed so it will be there to let you know if you
ever do get water in your fuel.
If the light comes on at any other time, use this chart.
"WATER IN FUEL" LIGHT CHART
Problem
Light comes on intermittently.
Light stays on:
1. At temperatures above
freezing.
2. At temperatures below
freezing.
Recommended Action
Drain water from fuel filter.
Drain fuel filter immediately. If no
water can be drained and light stays
on, see your dealer for assistance.
Drain fuel filter immediately. If no
water can be drained
-
water may
be frozen. Open the air bleed valve
to check for fuel pressure. If no fuel
pressure is present, replace the fuel
filter.
3. Immediately after refueling
-
Fuel tank purging required. See
large amount of water possibly your dealer for assistance.
pumped into fuel tank.
Hesitation or "flat" performance at high speed or during hard acceleration
may be an indication of premature fuel filter plugging due to dirty or
contaminated fuel. The filter element may need to be changed if this
happens. See your dealer for assistance.
NOTICE:
If you drive when this warning light is on, you can damage your
fuel injection system and your engine. If the light comes on right
after you refuel, it means water was pumped into your fuel tank.
Turn off your engine immediately. Then, have the water drained
at once.
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