I was heading to work this morning, and my truck died suddenly at about 75 miles an hour. I just lost power, and when I got it off the highway, I realized the engine had died. It would not restart. It would crank just fine, but would not start. I didn't have all my tools, so I couldn't do much. I think I had fuel pressure since I was able to stick the key in the Schroeder test valve and it shot fuel out. The last time it didn't want to start (November), I replaced the crank position sensor, and that fixed it, so I started messing with that cable, and I got it to try to start. It would start for about 3 seconds, and opening the throttle would kill it. Got it towed, and when I got it home, I bypassed the crank position cable with a new set of wires, and that didn't seem to do it. It won't even try now. I am not sure where to look. The CEL is on, but it has been on for the evap system for a while now. I will check it again to see of there is anything new, but other than that, I am not sure where to even look. It has been burning more oil than it should (about a quart a week), but it has not been running bad (sputtering or anything), so I am not sure where to even look for this one. Its a 98 4x4 with the 4.0L engine and a manual transmission at 177,309 miles on it. Any thoughts are appreciated.

 

Good idea to scan for trouble code clues, post All code Numbers as they can help focus your trouble shoot. We are supposed to begin with & put right the Lowest trouble code number first, then work out way up the list.
Takes Air, Fuel, Compression & Spark to make em run, so find out whats going missing.

From what you've posted, it kinda sounds like spark has gone missing & you can safely check that with your inductive timing light on any easy to get at plug wire.
Anyway, let the trouble code Numbers steer your trouble shoot & repair. Let us know what you find.

 

Wouldn't you know it, I must have run the battery low enough to reset the ECU because now it shows no historic faults, no pending faults, and no current faults. I just hooked an oscilloscope up to the firing lines on the coil pack, and it stayed at a constant voltage, so there is no signal to fire the plugs. I also hooked the scope up to one of the lines for the injectors, and again, so signal to spay fuel either when trying to start. I know the scope was hooked properly because I could see the voltage dip when I cranked, but no actual signal on either one, so the computer thinks it doesn't need to run either. I also checked the crank position sensor with both the oscope and multimeter. The sensor reads 500 ohms, which I will believe is correct since it is just a coil of wire, and I get a signal on the scope. I also tried just brushing a magnet near the sensor and also get a reading that way, so I think the sensor is working. In addition, I also unplugged the cam position sensor just to see if I could force the computer into fallback mode. That didn't seem to make a difference either. What other sensor could tell the PCM not to work? Maybe time to try replacing the PCM?

 

Ok, good find on the low battery voltage. Before you go any further, using your smart computer controlled battery charger, put the battery on a low rate of charge, say 6-8 amp setting for flooded cell battery & let it recharge Slowly, so as not to over heat & warp the plates.
On a low amp setting it'll take a Deeper recharge, as the acid has more time to penetrate the plates deeper, so converts more of the sulfate & cleans the plates better for more active surface area.

After the battery is back up to a full charge, use your inductive timing light to test for spark & your fuel pressure gauge to test for proper fuel pressure & let us know what you find.

Seeing as how you seem to like doing your own trouble shooting & wrench turning, consider using, borrowing, or coming by a ELM scan tool, running FORScan diagnostic software on the viewing device of your choice as discussed here, https://www.ford-trucks.com/forums/1...-scantool.html, as it can query All of the vehicle computer/controllers for an in depth scan of trouble code clues (in case you have more than one problem) & they can Really help focus & shorten a trouble shoot as I found.

EDIT: At KOEO, are the dash warning lights coming on & going through their self checks & turning off? If not, look under hood at the ECM power relay, maybe try thumping it to see if it'll wake up & work, or swap it out for a like one not needed to run the engine, like the horn power relay. If that works, replace the old relay. They at a common problem part on our Rangers, so often deserve a spot high up on our suspect list if the dash is dark at KOEO.
More thoughts for consideration, let us know what you find.

 

Thanks. I do have one of the Wifi adapters and was using TorqueLite to scan the computer. That's how I know there were no faults. I pulled the PCM out this afternoon and checked it for burns and bad solder joints. Nothing looks out of the ordinary. I am an electrical engineer by trade, so its not the first time I've looked at one. Unfortunately, I don't have a good battery charger, so I borrowed my wife's car to charge it up and had that plugged in when trying to start, so I know the voltage was good when testing everything. I also plugged the computer back in and checked power to the PCM and all of the ground pins. They all seem to register just fine. No unusual resistance and all good power. I am not sure where to check next. It seems something is telling the PCM to not fire the plugs or run the injectors, but I thought the only thing that could do that was the crank position sensor, which seems to be sending a good signal. I am not sure where else to check at this point. I read somewhere that possibly a mis-registering TPS could do this? Maybe?

 

SO, can we conclude from this that at KOEO all the dash warning lights come on & go through their self checks & turn off, to indicate the computer is getting power when we turn the ignition key on?

 

Yes. All the lights go through their checks and turn on and off properly, so it doesn't seem like the computer. However, that would say its a sensor, but the crank position sensor is working, and I can't seem to confirm what other sensors could cause this problem. I'm thinking the next step is to unplug every unneeded sensor and then try again. I have not found a good explanation of which ones are necessary to start the engine and which are not. It seems to depend some on the year, so if anyone has a good link for that, I would appreciate it.

 

Ok that's good feedback, so with the computer indicating it's going through system self checks, we know for sure the computer is getting power.

With no spark, or fuel injector action it's Highly unusual for there to be no lit CEL nor codes to be stored.

At KOEO, before you crank the engine, can you hear the fuel pump come on for a couple of seconds to prime the system, then turn off?

Is the PATS anti-theft light rapidly blinking?

 

I do hear the fuel pump come on, and when the battery was low, the fuel pump relay was clicking on and off. In addition, I still have pressure at the rail, so I doubt that's it. As far as I know, my truck does not have any anti-theft on it. I lost the original keys, and the standard remakes have been working fine for 3 years now. Also, I don't have a blinking light anywhere on the dash I've ever noticed. As for the self check lights and no codes, its not the first time I've had that happen. I've replaced both the crank position sensor and cam position sensor since I've owned it, and there was no code for either one of those. I'm guessing no CEL on since the batter dipped too low. Probably ran the computer low enough to kill the back up battery and reset the CEL, and since it hasn't been able to start since then, no light. Edit: Update I pulled the MAF, TPS, and intake air sensor connectors loose, hooked it up to my wife's car, and tried. I didn't crank for a long time, but it didn't seem to even try. I also tried scanning the computer again. No faults still. Unless there is another sensor that could cause a no start, I am thinking computer. I just don't know what else it could be at this point.

 

Since you have a ELM scan tool, try loading & running FORScan on the viewing device of your choice, as it's tweaked for Fords & can query All of your vehicle sensors for missing or corrupt PID's & computer/controllers for any pending or set trouble code clues, any of which could help focus your trouble shoot.

Get a fuel pressure reading with a gauge attached to the fuel rail Schrader valve test port.
Use your inductive timing light to safely check for spark when you crank the engine & let us know what you find.

You never did close out, or provide any fix feedback on your 2014 & 2015 intermittent no start problem threads, so if you discovered what was causing those, post up any finding, as it might figure in on your current sudden stall woe

 

Get the battery back up to a Full charge before you scan with FORScan. EDIT: Don't use the wifes car alternator to do it, you'll overheat her alternator & your battery, as the alternator isn't designed to Fully recharge a battery. Use a smart/computer controlled battery charger that's designed to recharge a depleted battery. If you don't have one, now is a good time to justify investing in a temperature compensating one like the Clore PL2310 here http://www.cloreautomotive.com/sku.php?id=502.

I'd also test, or have the alternator & battery load tested, to find out why the battery was in such a low state of charge. Low battery, or alternator output can cause all sorts of operating mischief.

 

I've been trying different tests today. I used FORScan. Very nice software. Wish I had tried it sooner. Unfortunately, nothing useful. I am attaching the logs from my scan, but it appears the PCM only has code P1000, which makes sense since I pulled the computer for inspection. The other modules report some codes, but all seem to be related to low battery, which also makes sense since the battery has been at low voltage from trying to start the motor. I did this test after pulling the battery out and getting the alternator tested. The alternator tested fine. The battery is at the auto store charging. It was too weak to do a load test. For running FORScan, I put the alternator back in, and used my wife's car's battery for power. I had it hooked through my jumper cables, but they are 2 gauge wire and tie directly into the truck's power system, so it was still at 12 volts at the battery terminals when I did the tests. At this point, I am at a loss as to what else it could be. The more I thought about it, if it was the PCM, it wouldn't have tried to restart on the side of the road, but it did so it seems to be a bad signal somewhere. That's the only thing that makes any kind of sense.

 

Update: Just got the battery back from autozone, fully charged and test good. I realized I forgot to answer the earlier question. As for the previous threads, one was seemingly solved by a new cam position sensor, and the other solved by a new crank position sensor. In both cases, there was no code thrown, only a crank, no start condition. I replaced the cam position on the advice of a mechanic who couldn't find anything wrong. That fixed the problem for about 2 years. When it came back, I bench tested that sensor, and it seemed good. I then went for the crank position sensor because everything I read said that it was the only sensor that could cause that problem. Replacing it in October fixed that problem until now. Again, no code or anything. Just a blind guess that was never proven, so I don't really know if that fixed it or what.

 

Ok good to hear the battery took a charge & tested ok.

 

If the engine computer is getting power, the engine cranks but won't start, then it's missing spark, fuel, or compression. Since we don't think the timing chain broke, that sorta leaves you looking at no spark, no injector squirt, or both.

Seeing as how you've previously had low fuel pressure, I'd get a proper fuel pressure test gauge hooked up to the fuel rail Schrader valve test port to check for proper fuel pressure. Those numbers are posted in your previous threads.
I'd also use an inductive timing light to safely test for spark.

If no spark, disconnect the coil pack electrical connector to make sure you have B+ there at KOEO. Same for the fuel injectors electrical connectors, B+ should be there at KOEO too.
Both the fuel injectors & coil pack are ground switched by the computer ground switching drivers, so it's not likely all of them have gone bad all at once, so that's why I asked if this puppy had anti-theft, because if it does & it got triggered, no spark, or fuel.

If you don't have spark or fuel, then the answer is staring us in the face but my reasoning has laid down on me because I can't see the answer. Not likely that both the crank & cam sensors that went bad before, both suddenly went bad at the same time either.

Maybe a member with a clear mind reading this will chime in & enlighten us while you do the fuel pressure & timing light tests.