03 Ford E350 7.3l Engine Diagram

Top 10 7.3L Ford Power Stroke Crank-No-Start Causes

Totally legitimate reasons why she just won't fire.

When it comes to diesel-engine hierarchy, we feel it's fair to say Ford's 1994-2003 7.3L Power Stroke engine sits squarely in a middle space among all of the oil burners that have powered heavy-duty pickup trucks. Like the 6.0L powerplant that immediately followed it in 2003, the good-old "seven-three" is either loved or hated (figuratively) by diesel fans throughout the hobby.

Per well-documented history, the 7.3L Ford Power Stroke engine is a torquey, tireless worker. It's the proverbial "engine that runs forever," provided maintenance is diligent and towing/hauling demands that are placed on the powerplant are reasonable. The 7.3L Power Stroke engine has a dependable internal makeup, not one that supports using it for high-performance endeavors, without it being modified accordingly beforehand.

Despite its favorable qualities, there are a few chinks in the 7.3L engine's operational armor. Occasionally not starting—despite cranking—is one of them, and through years of experiencing the problems firsthand or hearing from enthusiasts who have dealt with no-start nuances, we've come to understand what the reasons are. In no particular ranking or order, this is our collection of those causes.

Common 7.3L Power Stroke Crank-No-Start Causes (Electrical)

Battery: A 7.3L Ford Power Stroke engine might crank over but will not start without sufficient voltage for the ECM. Low battery power also can prevent glow plugs from warming properly (in cold climates) and prevent the engine from turning fast enough to fire.

Engine Control Module: Yes, an ECM can give out. And if/when it does, a no-start condition is definite.

Cam Position Sensor: Abbreviated as simply "CPS," it's a part that doesn't really become a concern until an engine has more than 100,000 miles. It initially causes a 7.3L Ford Power Stroke engine to idle erratically, suddenly shut off, and eventually not start at all. Occasionally, an engine with a bad CPS will eventually refire after a truck sits for a while. Verifying a bad one is done by watching the tachometer as you try and start the engine. If the needle doesn't move, the sensor's done. We recommend keeping a new CPS on standby somewhere in your truck, because again, they typically fail at any time after 100,000 miles are reached.

Injector Driver Module: The IDM is found on driver's side of 1994-2003 rigs, usually mounted on the fender. Like the CPS, symptoms of failure are misfiring, shutting off, and not starting. It is believed that moisture or water getting into the IDM are two of the main causes for its failure, but they also can cause no-start conditions when wiring into the module is damaged.

Injection Pressure Regulator Valve: The IPR literally is the main vein in a 7.3L Ford Power Stroke engine's high-pressure oil system. It's located in the engine's valley, attached to the high-pressure oil pump (HPOP). The valve is known to stick and prevent oil flow to the injectors, its solenoid fails, or seals and wires somehow become damaged. While it's a long shot, a retainer nut on the solenoid also can loosen. A severely rough-running engine is a symptom of IPR failure, as is the engine not starting due to insufficient oil pressure for the injectors.

Injector Control Pressure Sensor: When an ICP is failing, the engine runs extremely rough as load is imposed (under throttle), and the condition can eventually contribute to a 7.3L's inability to start. Oil contamination in the wiring usually is the cause. Inspection (it's threaded into the driver's-side cylinder head) is the first point of diagnosis, and a unique way of verifying the sensor's failure is to bypass it by unplug its wiring harness (but do not drive in this condition). If the engine runs smoothly with the connector unplugged, the ICP is bad.

Common 7.3L Power Stroke Crank-No-Start Causes (Fuel)

Filter: Simple logic here. A blocked/clogged fuel filter not only contributes to a 7.3L Ford Power Stroke engine not starting, it definitely will limit the engine's power if it does actually start and run.

Lift Pump: Again, no fuel, no start. If all is well with the HPOP, CPS, ICP, IDM, and IPR, looking into the fuel bowl while the engine is cranking (a second person is needed for this). An absence of diesel will quickly confirm the no-start condition is the result of a pump being down. Actually verifying cranking fuel pressure with a gauge is the proper diagnosis. The reading should be 60-65 psi.

Bowl-Heater Element: If this part experiences an electrical short and its underhood fuse (No. 22) blows, the ECM—of all components that could be affected—is knocked offline, and the engine will not start. Maxi fuses are inexpensive, and keeping some in the truck to have as backups is a good idea.

Injectors: This is a long-shot fueling concern that can lead to a crank-no-start condition. O-ring failure is typical for high-mileage 7.3L Ford Power Stroke engines, but injectors will give out if they are not lubricated properly.

Low-, and High-Pressure Oil Pumps: The oil level (approximately 1 inch from the top of the inspection window) and pressure (500 psi) for this system must be accurate at all times. A failing LPOP will test with pressure of less than 50 psi at idle, and below 100 psi under load. An HPOP is bad when pressure does not reach a minimum 500 psi.

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Source: https://www.motortrend.com/features/7-3-liter-ford-power-stroke-no-start-causes/