My Power Stroke Won't Start

Terry Welshans (Popperboy1)

twelshan@metrarr.com

My Ford Power Stroke Diesel engine won’t 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 let’s 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 doesn’t, 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 relay’s small terminal is getting battery voltage when the key is turned to the start position. If you don’t have a test light or voltmeter, connect a jumper wire from the battery positive to the start relay’s small terminal. If the relay doesn’t 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 down, too.

Test 3: Turn the key and the starter and engine turn over, but the engine won’t 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 won’t 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 fuel.

Step five, if the HP oil system pressure doesn’t 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 be bad.

Test 4: Do you have warranty coverage? If this quick troubleshooting guide didn’t 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.