1993 GMC SIERRA water pump

I
I
‘4
!b P4
LL
1
PO593
The coolant level should be at or above the COLD mark. If it isn’t, you may
have a leak in the radiator hoses, heater hoses, radiator, water pump or
somewhere else in the cooling system.
Heater and radiator hoses, and other engine parts, can be very\
hot.
-, Don’t touch them. If you do, you can be burned.
Don’t run the engine
if there is a leak. If you run the engine, it cou
lose all coolant. That could cause an engine fire, and you could be
burned. Get any leak fixed before you drive the vehicle.
I I
NOTICE
Engine damage from running your engine without coolant isn’t covered by
I your warranty.
If there seems to be no leak, check to see if the electric engine fan (if you
have one) is running.
If the engine is overheating, the fan should be running.
If it isn’t, your vehicle needs service.
Start the engine again to see
if the regular fan runs when the engine does.
If it doesn’t, your vehicle needs service. Turn off the engine.
How to Add Coolant to the Coolant Recovery Tank
If you haven’t found a problem yet, but the coolant level isn’t at or above
COLD, add a 50hO mixture of clean water (preferably distilled) and a proper
5-1 2
ProCarManuals.com

Cold Weather Operation
In cold weather (below 20”F, or -7°C)’ use 1-D or “Winterized” Number 2-D
fuel (a blend of 1-D and 2-D). Be sure you get the right fuel. In very cold
temperatures (when it stays below
0°F or -18”C), use Number 1-D.
If you’re driving in very cold temperatures and can’t get\
Number 1-D or a
“winterized” Number 2-D, you can use one gallon of kerosene for every two
gallons of diesel fuel. Once you add the kerosene, run your engine for
several minutes
so the fuels will mix. Add kerosene only when the
temperature falls below
0°F (-18°C)’ because the fuel economy of kerosene
isn’t as good as that of diesel fuel.
NOTICE I
Never use home heatina oil o
I
1
In cold weather, your fuel filter may become clogged, especiall\
y if you use
Number 2-D diesel fuel that hasn’t been “winterized.” To unclog it, just warm the
filter to between 32°F and
50°F (0°C to 10°C). You won’t need to replace it.
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.
AT€
PBOlO
6-7
ProCarManuals.com

Service & Appearance Care
This light also should come on 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 FUE
PROBLEM
Light comes on intermittently.
1) Temperatures above freezing.
Light stays on
2) Temperatures below freezing.
3) Immediately after refueling -
Large amounts of water
probably pumped into the
tank.
.” LIGHT CHART
RECOMMENDED ACTION
Drain water from fuel filter.
Drain fuel filter immediately.
If nc
water is drained and light stays on
-
replace fuel filter.
Drain fuel filter immediately.
If no
water can be drained
- water may be
frozen. Open air bleed
to check for
fuel pressure.
If no fuel pressure
replace filter.
Fuel tank purging required. See your
dealer for assistance.
1
iesitation or “flat” performance at high speed or hard acceleration may be an
ndication 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
or assistance.
f you drive when this warning light is on, you can damage your fuel I
njection system and your engine. If the light comes on right after you
efuel,
it means water was pumped into your fuel tank. Turn off your
mgine immediately. Then, have the water drained at once.
I
To drain water:
1. Remove the fuel tank cap.
2. Connect a hose going from the water drain valve to a fuel-resistant
container.
6-8
ProCarManuals.com

7
F
K2451
..
3. With the engine off, open the water drain valve 2 to 3 turns.
4. Start the engine and allow it to idle for 1 to 2 minutes, or until clear fuel
is observed.
5. Stop the engine and close the water drain valve.
6. Install the fuel tank cap.
If the
WATER IN FUEL light comes on again after driving a short distance or
the engine runs rough or stalls-a large amount of water has probably been
pumped into the fuel tank. The fuel tank should be purged.
~ CAUTION I
A Diesel fuel containing water is still flammable. You could h~ burmi.
If you eve:r try to drain water from your fuel, kee,p sparks mes d.
. smoking materials away from the mixture.
If there is water in your diesel fuel and the weather is warm or humid,
fungus and bacteria can grow in the fuel. They can damage your fuel
system. You'll need a diesel fuel biocide
to sterilize your fuel system. Your
dealer can advise you
if you ever need this.
If your fuel tank needs to be purged to remove water, see your dealer or
a qualified service technician. Improper purging can damage your fuel
system.
6-9
ProCarManuals.com