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If your Power Stroke won't start, Terry Welshans helps you figure out why.
My Ford Power Stroke Diesel engine wonít start....
Now how many times have we heard someone say that in one of the Forums? The
good news is that this is a simple circuit to troubleshoot. Lets begin by
figuring out the symptom a little better, then letís see what can go wrong to
cause that symptom.
Test 1: Turn the ignition key and nothing happens. No lights on the dash, not
chimes from the cab, nothing.
Step one, turn on the headlights - if they do not light, then your
battery is dead, so check the batteries. Someone may have stolen them, the
cables are off, or the lights were left on and the batteries ran down. It
could also be loose cable terminals. Remove the cables and clean the battery
terminals and the inside of the clamps until they are shiny, then bolt them
back on and try starting again.
Step two, get a jump start from a BIG battery or better yet, get your
batteries charged and try starting again.
Step three, find out why the batteries went dead. Look for a circuit that
is energized when it is switched off - it could be a stuck relay.
Test 2: Turn the key and the dash lights are on, but nothing happens up in
the engine room.
Step one, open the hood and have someone turn the key to the start
position. Listen for the starter relay over on the passenger side fender
area near the big red battery cables; it should click when the key is turned
to start. If it doesnít, then it is not getting power. This would be a
great time to see if the truck has a starter interrupter kill circuit. Some
of these modules are driven by the keyless entry output from the Generic
Electronic Module (GEM), and some are manual switches. It could be doing its
job, or is broken. Jump it out if you can and try starting again.
Step two, check the power to the starter relay by following the circuit.
It starts at the battery positive as a BIG red cable, heads over to the
starter relay, then out a small wire then thru a FUSE LINK to the power
distribution block. There, fuse #20 (50 amp) powers the ignition switch.
When you turn the key to the start position power goes on to the Junction
Box / Fuse Panel fuse #15 (30 amp) and then to the Clutch Pedal Position
Switch (CPPS) for manual transmissions and on to the starter relay or
to a CPPS jumper for automatic transmissions then to the Digital
Transmission Range Sensor (DTRS) and then on to the starter relay.
Step three, use a test light or voltmeter to see if the starter relayís
small terminal is getting battery voltage when the key is turned to the
start position. If you donít have a test light or voltmeter, connect a
jumper wire from the battery positive to the start relayís small terminal.
If the relay doesnít click the relay is bad. If the relay clicks and the
engine starts, the problem is in the wire from the switch to the relay.
Check the fuse link and the two fuses for continuity, and if they are good,
check continuity through the jumper and the DTRS (automatic) or the CPPS
(manual). It could be you are not in Park or Neutral or have the clutch
Test 3: Turn the key and the starter and engine turn over, but the engine wonít
start. This is a most likely a computer or fuel injector problem.
Step one, open the drain on the fuel filter / separator and see if fuel
and/or water comes out. Is it water, diesel or gasoline? If water or
gasoline comes out, the injectors may be ruined. In that case, call for a
tow and get out your wallet. If no fuel comes out, do you hear the fuel pump
running when you turn the key on? If the fuel pump is running but not
pumping fuel then you could be out of fuel, have a plugged fuel filter or a
damaged fuel line restricting the flow of fuel.
Step two, check your fuel gauge. The fuel gauge may be stuck on
"Full", so to be on the safe side, just pour in that spare 5
gallon can of diesel that you carry in the tool box. Do you have diesel fuel
in the tank now? If no fuel, get a tow or a ride to a fuel stop, you know
what to do when you get there.
Step three, if the engine wonít start when it cranks over and the tach
stays at zero, the Camshaft Position Sensor (CPS) is dead (except on 2002's,
where the tach is dead until the engine starts). The Powertrain Control
Module (PCM) must see at least 100 RPM for the PCM to send injection signals
to the Injector Driver Module (IDM). Slow cranking speed could be caused by
low batteries or loose / dirty battery connections.
Step four, it could also be that the fuel injectors are not firing
because the High Pressure (HP) oil system has less than 375 PSI or the
pulses are not getting to the injectors. The injectors are hydraulicly
operated and controlled by a signal pulse that turns them on. If the HP oil
pressure is less than 375 PSI there is not enough pressure to inject the
Step five, if the HP oil system pressure doesnít come up, the pump may
be bad, out of oil, or the pressure regulator is bad. It could also be that
you have 15W40 oil in a cold climate. use 10W30 in freezing temperatures to
prevent this problem.
Step six, if the injectors do not get the signal to fire, the PCM or the
IDM may be bad or have no power. Check the PCM power fuse 30, the diode,
fuse 34 and the IDM fuse 27 may be open, too. Last, the PCM power relay may
Test 4: Do you have warranty coverage? If this quick troubleshooting guide
didnít find the problem, then you most likely need professional help to solve
the mystery, so get your truck towed to a shop that knows diesel engines.
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