Ford has been producing the Power Stroke for many years. In mid-1999, it made a significant change in the design by adding additional electronic controls. Early in 2003, it brought out the 6.0L with even more electronics and emissions systems including the addition of the Controller Area Network (CAN). In 2008, the 6.4L was the next change, adding even more electronics and emissions systems. It was also the last of the Navistar engines. Since 2011, the power behind the Ford diesels comes from a Ford 6.7L.
In this IDS screenshot, you can see the EOT is telling the PCM that the engine oil temperature is 141-degrees when it is actually about 50degrees.
Where do we start in this discussion? This article will start with the 1999.5 MY 7.3l and 2003.25 MY 6.0l engines. Getting to know these engines and working on them is not something that can be covered in one article, so my goal is to give you the starting point when one of these vehicles comes into your shop with a hard start/no start concern. Most of the procedure I’m going to discuss will serve you on any of these vehicles.
When I first started certifying Ford dealer diesel technicians as a Ford Service Training Instructor, it was on the 1999.5 MY 7.3l Power Stroke with electronic engine controls. One of the things we told techs to use was the hard start/no start or the poor performance diagnostic procedure sheets. Ford required that those sheets be followed and results recorded as a part of any warranty claim.
Can the scan tool talk to the truck? This IDS screenshot is showing that the PCM is not talking. This problem must be fixed first.
Ford also wanted techs to follow them in order, as they were in a logical sequence that made sense, or at least as much sense as any printed set of directions can have. In the case of the poor performance sheets, the step order was critical in making sure that concerns that would cause a vehicle to fail a boost test were tested and found before the tech tried to do the boost test.
You can Google any of these engines and get an overload of opinions, comments, concerns, repairs and other information that might or might not be useful to you. Valuable sources of information, however, that is not fit into a good procedure can be a time killer. The best way to approach these vehicles is by using the test procedures that Ford developed; they worked then and still work well today.
I’ll also point out two traps that you may encounter if you don’t take into account PCM (Powertrain Control Module) system operation and the age of these vehicles.
First Things First
But let’s start at the beginning; if you’re given an RO for 7.3l or 6.0l Power Stroke that the customer says is hard starting. What do you do first?
This tractor will run on diesel fuel that may not work in a Power Stroke. Farm fuel might be very different than diesel fuel sold for highway use.
I’ve been in this business for 35 years and have seen significant changes. In spite of that, I still find that I will find more problems and find them faster if I follow the same four-step procedure on every vehicle; 1. Confirm the problem exists as stated by the customer, 2. Check for applicable service information and TSBs, 3. Perform a visual inspection, and 4. Select the least invasive initial test procedure.
You pull up the HS/NS (hard start/no start) procedure sheet, give it a quick review and head out to the truck.
In Step 1, Ford wants you to do an inspection on these items on either engine:
1. Fuel
2. Oil
3. Coolant
4. Hoses
5. Leaks
6. Electrical system
If you’re like me, you’re going to walk out to the truck with your IDS scan tool or an aftermarket one that you know can talk to this vehicle. You’re going to have a copy of Ford’s hard start/no start procedure sheet that you have on your laptop or have printed out from doing a quick literature review on PTS, or one of the other information services. You may have a couple of TSBs that may pertain to your vehicle that you want to check out as well.
This 6.0L F250 has aftermarket exhaust, body trim, hood and front bumper. What’s been changed under the hood? Does it have a performance chip?
A 7.3l might be 14 years old, a 6.0l may be 10. Is it a low-mileage cream puff that somebody has babied and cared for? Is it a family work truck, mostly hauling kids and stuff with the extended trip pulling that 40-foot fifth wheel? Is it a work truck that sees the inside of a garage when it’s serviced? (Frequently serviced or infrequently?) Is it one that’s been modified and has a chip? Has it been several of these vehicles over its life? How many miles does it have on it?
The answers to these questions will tell you where to begin doing your initial investigations. If it’s a farm work truck, is the owner using farm fuel? Is that farm fuel road use rated? Is it old and full of algae? Is it a summer blend and this is now winter or the reverse?
This turbo from a 7.3L has ingested debris, recommend an engine mechanical check for that hard start concern.
Let me stop here a moment and give those of you new to this business some advice. Those of us who’ve “been there, done that” ask these and dozens questions more as we walk up to any vehicle we’re going to analyze. I call it “Inspection Mode.” When I am in my technician inspection mode, I can walk around a car and tell you in less than a minute if the vehicle has had bodywork done to it, has four matching tires and has ride height concerns. This is done without bending over, just simply walking around the vehicle and observing. (I did many alignments as a line technician.)
I’m going to take that walk around the truck and get as much information as the truck will offer by observation. Yes, there’s a fifth wheel in the bed or those holes tell me there was once upon a time. Exhaust system is reasonably OE in configuration. Truck has been used as a truck. Open the door, what does the inside look like? Plug the scan tool in.
A 2008 6.4L F250 Power Stroke
Get in the truck and turn the key to the on position. Can you hear relays click on? Do all of the dash’s warning lights come on? What does the MIL do? Can you hear the fuel pump turn on and run? How about the Wait to Start Lamp? Will the scan tool communicate with the PCM?
Pop the hood, battery condition, oil level, coolant levels and condition, anything that will give information about the condition and life of the truck.
Does the truck crank over? No start concerns are interesting as your analysis path might go in two different directions. I’m heading down a different path for what I’m checking if it’s crank-no-start then if it’s no-crank-no-start.
The procedure sheet for the 7.3 has 10 steps and the procedure sheet for the 6.0 has 12 steps. Several of the first steps in these procedures are simply more detailed versions of the initial visual inspection. Let’s look at the procedure sheet and begin.
The first trap and the first question on the sheet is the direction to go to the final step to check the glow plug system if engine oil temp is below 60 degrees. If you don’t understand PCM engine control this one will bite you.
Here’s a case study from a 2001 Ford Excursion with a confirmed hard start cold. The truck has sat outside in 40 degree weather for the past six hours.
Here’s the question: How do you know if the engine oil temp is less than 60 degrees?
Use of the correct oil is critical to starting and running on the 7.3 and 6.0 engines.
For those of you reaching for an infrared temperature tool or remarking that the truck has sat outside in 40-degree weather for more than hours, you might be technically correct. However, you have missed the real answer and will spend the next several hours checking a glow plug system that might be in perfect working condition.
The answer to the question is not whether engine oil actually is below 60 degrees, you get the answer to the question by determining if the PCM thinks engine oil temp is below 60 degrees. That is why I walk out to the truck with the scan tool.
When the key is turned to start the PCM looks at Intake Air Temperature (IAT) and if below a certain temperature will look at the Engine Oil Temperature (EOT) to see if the glow plugs should be turned on. You need to ask every question about engine controls from the point of view of: What does the PCM think?
In this case, the PCM saw EOT at 140-degrees. The PCM did not report a concern as the failure was within operating parameters of the sensor and the PCM does not do a rationality check on this sensor.
This is what a 2001 Excursion with the 7.3L Power Stroke and California emissions package looked like new when you open the hood.
Here’s another quick series of checks on a truck that is a no start. What about the relays clicking and the MIL lamp? One of the possible failures that will cause the truck to come in on the hook is when a sensor shorts VREF to ground. In this case, the scan tool will not communicate with the PCM.
The Engine Back Pressure (EBP) sensor is one that will do that. The EBP sensor monitors exhaust backpressure for the PCM controlled waste-gate. If it or any other sensor shorts VREF to ground the PCM shuts itself down and the symptoms are that the MIL will not come on and prove out, none of the relays for glow plugs or the fuel pump will be energized.
Trap Number 2 to be aware if as you perform your analysis and this holds true for gas engines as well. Many procedure sheets and pinpoint tests make certain assumptions. You need to have checked those assumptions prior to getting into one of these test routines.
For example, you will note that in the list of checks to be performed above that the electrical system is mentioned. A good battery or batteries in a truck are critical to ease of starting. It will surprise you how well an engine might crank over with batteries that need replacing and are in fact the cause of the concern. Once system voltage drops below 9.0V, the PCM might shut down and on the Power Strokes, the Injector Driver Module (IDM) might not be able to supply the necessary energy to open the injectors.
The starter might not be able to crank the engine over fast enough to create enough compression to ignite the mixture, even with glow plugs. Bad grounds and corroded power connections will cause PCM control concerns.
When inspecting a turbo for foreign part ingestion this is what you want to see: clean, no grit, no sign of foreign parts going through.
In the 7.3’s and 6.0L Power Strokes, engine oil is critical to operation. Engine oil is the fluid used to control injection spray. Low oil, incorrect oil and even worn out additives in the oil will cause you many different types of concerns. I had a 2002 Excursion with the 7.3L as a training unit. I was driving it one day and noticed it running poorly, some bucking and jerking; unknown to me at that point the engine had developed an oil leak and was two quarts low.
That’s right just two quarts low and the truck already had a driveability concern. Many long-time Ford expert technicians will automatically do an oil change as part of any running concern analysis.
What then is the specific gotcha in this procedure? The mechanical condition of the engine.
These procedures were written for trucks that were still under warranty. It was reasonable to assume that a mechanical concern may not be a likely cause although the poor performance procedure sheet does have you check for a dusted engine. There is a fairly fast way to suspect that an engine is dusted beyond high mileage.
We go back to our under hood visual inspection, how dirty is it under that hood? What does the truck have on it for air filtration? Are there some telltales of excessive blow-by at air duct and breather line connections?
The fastest way to do an initial test to check for a dusted engine is to remove the air duct to the turbo inlet. Look inside and then wipe the surface with your fingers and rub your fingers together. Dirt and larger object ingestion is pretty easy to see. If it looks as if the turbine has been sand blasted or damaged, you’re looking at engine mechanical concerns. If when you rub your fingers together you feel grit it’s time to recommend an engine mechanical inspection.
Fuel is one of the other quick checks. You’ll notice that there are more detailed test procedures for the fuel system, but the first is to simply make sure the truck isn’t out of fuel. Yes, it really does happen. Next drain some fuel from the filter assembly and make sure diesel fuel comes out.
If you visual inspection of the turbo has a turbine that looks like either of these then it’s time to recommend compression testing or other mechanical testing.
Colored fuel (in Michigan it is a reddish pink) means that is non-road taxed farm fuel. If MDOT catches your customer using that on the highway, they’re in for a nasty fine. Let’s not jump too fast here, however, as not all farm fuel is “bad” for these trucks. Navistar made the 7.3 -6.0l Power Stoke, and that is the only thing in common with a Navistar diesel in a farm implement. If the farm fuel is road use rated quality and not from the wrong seasonal blend, then that is not likely to be your starting problem.
I have seen gasoline come out of these trucks; well, I’ve also seen diesel fuel come out of the system on a gasoline engine car. There might be water in there. The other concern that you might run across is someone using biodiesel.
There are two types of biodiesel. One is the actual road use rated fuel produced for use in vehicles. Ford does not recommend the use of biodiesel in the 7.3 and only recommends B5 or 5 percent bio in the 6.0. I did a number of experiments with Biodiesel on my own while I was with Ford and found that I could run B20, 20 percent bio with no adverse effects in the short term. We have a station in my town that sells B20 mixed with 50-cetane diesel that works really well.
The one to be really concerned with is the “bio” diesel that started life in a fast food fryer. I don’t care to get flamed on this by those of you who would want to tell me that you’ve been using that stuff for years in your trucks without problems. I’m sure that happens and more power to you. Let me simply say that for ease of starting any vehicle a quality fuel, seasonally blended needs to be used.
Often, the cause for (or at least a diagnostic direction for) the underlying problem can be determined in a careful visual inspection. But a visual inspection is only as good as the person doing it, and knowing what you’re looking at and what it’s supposed to look like are two conditions you have to meet before you even begin.
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