Hi everyone,
Just joined here for my son's 1999 Ford Ranger (4.0L, 4X4, automatic) after great success on the F250 forums.
The truck will very occasionally actually start. When it does, it runs great, sounds good etc. But it will suddenly die (like the key has been turned off) and then won't start again.
Usually it just cranks and cranks and doesn't even try to start.
There are no error codes - actually read them and it shows 0 codes.
I have checked the fuel pressure and it's between 60 - 65 lbs and stays there all the time even when it does fire up and run. It does not dip or go away when the truck dies, it's still good and solid 60 - 65.
I've cleaned the MAF and the IAC. It has new plugs and wires. I checked all the fuses (with a multi-meter) and they're all good. I've put new relays into the fuel pump relays spot.
I've done a lot of trolling through these forums and am not seeing anything that looks the same or have tried the solutions I've seen here.
Does anyone have any other ideas on what to check? I really don't want to just start randomly throwing parts at it.
I've heard some talk about the inertia switch - is the wiring an issue with those in the '99? Would the fuel pressure go to zero/low if the switch wiring was bad?
Any suggestions would be hugely appreciated.
Thanks in advance!

 

Welcome to the forum

You should do the 50/50 test on any engine when it cranks but doesn't start, from a lawn mower to a V12
Spray fuel into the intake, gasoline, Quick Start(ether), carb cleaner, brake cleaner, ect....................
Try to start
If it starts runs and dies you have a fuel delivery issue
If it doesn't start then its a spark issue(or compression)
50/50 instant results
Used since 1890's and the first gasoline engines, so time tested, lol

We will discount compression since it does run when it wants to

If 50/50 test shows No Spark then either computer is failing OR Crank sensor is failing

When you turn on the key the CEL(check engine light) should come on, means computer has booted up
Crank engine over, CEL should go OFF as soon as engine is turning, not started just turning, that mean Computer is getting a good timing signal from Crank sensor

Crank sensor is not hard to replace, and give a good look at its "tone wheel"(reluctor ring)
Crank sensor reads that wheel with teeth on back side of crank pulley, no touching just close to the teeth
1 tooth every 10deg, then 1 missing tooth to ID Top Dead Center(TDC)
Computer gets its timing signal from Crank sensor so it can time spark, no signal or dropped signal and spark stops
Crank sensor generates its own voltage, AC voltage, 0.5 to 8vAC
The only sensor that can stall a running engine

Computer
Do a sanity test since you have an OBD2 reader
Unplug MAF sensor, turn key on, start engine, if it will this time
CEL should come on and you will have a MAF sensor code
Plug it back in

You can unplug other sensors, for same sanity test

There is no "computer test"

 

Hi RonD,
Thanks for the feedback, I really appreciate it.
I will begin working through all those steps this morning with my son - again, thanks!
Question though, does the computer not throw a code for a bad/missing signal from the crank sensor?
Also, if I unplug the MAF, it should throw a code even if the engine doesn't start...correct?
I'll let you know what we find or if more questions come from this.
Thanks again!

 

Yes, all sensors and controls are monitored(but no fuel pressure sensor)
So if any are unplugged with key on it should set a code, the point of the "sanity test"
But................
Each sensor or control has several codes, each meaning something a little different
There are "lack of connection" codes and "out of range" codes
"Circuit code" can be bad wire or bad sensor/control device
"Range code" can be corroded wire, failing sensor/control, or what its monitoring "is out of range", i.e. temp, lean, rich, ect....

So starting the engine, if you can, can add more to sanity tests, even if sensor/control is unplugged

Yes, if crank sensor signal was intermittent you would expect a code for that, but these computers have less processing power than a 1970's vending machine, they really only have if/then and and/or processing
Which means humans need to diagnose issues with vehicle systems, these computers can not

Partial Ford OBD2 Code list here: https://www.therangerstation.com/tec...trouble_codes/

Watch the CEL, if CEL comes on when engine stalls that means computer is still on, if CEL doesn't come back on when engine stalls it means computer is OFF which is why engine stalled
PCM Relay in engine bay fuse box powers Computer(PCM), also most other engine systems

 

There are some important grounds also that probably should be checked. Highly unlikely since so many systems run off just a few grounds but you never know.

 

We finally got back to the truck, here's what we found.
CEL goes off when cranking and running. Disconnected the MAF and the CEL comes on and gives a code. Reconnect it, cleared the code and the CEL is back off.
Truck fired right up a couple mornings after this post and ran for a few minutes then died - no stutter, no missing then die, just simply dead, like the key had been turned off.
We sprayed starting fluid into the throttle body and it fired right up - like, immediately - and actually ran for about 15 seconds, then died again in the same way.
More starting fluid and it fired right up but didn't stay running more than a couple seconds.

So, according to the 50/50 test we have spark but a fuel delivery problem....right?
We have 60-ish lbs of fuel pressure (seems steady by the gauge).
Where else do I look? Is there something that controls the injectors that could be failing? I'm at a loss here.
Once the fuel line is charged, if the fuel pump has created line pressure but it then dies, will the pressure drop fast enough to see it on a dial gauge? Could the pump be the issue still? (New fuel pump relay so that's not the issue)

Thanks Glaze77 for the ground chart, I will definitely review it as this truck is older. I see there are couple related to the fuel tank, are there any others to check related to the fuel system? (I will check the MAF ground as well.)

Thanks for the help so far, I feel like we have made a good step forward isolating the major issue - thanks so much!
Hopefully we can get this thing running soon.
Thanks all.
Wayne.

 

The PCM(computer) runs the fuel injectors and also times the spark
Does CEL come back on after engine stalls, it should if PCM is still on, and if spark still works(50/50 test) then it is still on

Yes, it reads like fuel injectors are being shut off assuming fuel pressure stays above 25psi
1999 V6 Ranger does have PATS
One of its theft deterrents is to shut off fuel injectors, so this maybe a PCM issue
Before going down that road I would do two more tests
Each injector gets 12volts with key on from ONE WIRE, its daisy chained from one injector to the next
You can see that Red wire on each injector
That Red wire comes from PCM relay in engine fuse box and has SEVERAL splices because it also powers PCM, egr solenoid, evap solenoid, and a few other devices
So if that one red wire at the splice that goes to fuel injectors was corroded/damaged
Test voltage on any injector's red wire to battery ground to see if it has full 12v after engine stalls, should show Battery Voltage, 12.3v to 12.8v

You can rent NOID lights
These plug into any injectors wiring connector, they flash when injector is opened by computer
Injector pulses are milliseconds long so regular test lights don't really work
If NOID light stops flashing and engine dies that would confirm PCM is shutting off injectors for some reason

PCM also has a "Clear Flooded Engine" software, it shuts off fuel injector pulses to "clear a flooded engine", but it can only be initiated at 0RPMs, so driver can crank engine over with injectors off to dry it out
So there are two candidates, Clear flooded engine and PATS software that could "go bad" and cause the stalling

 

I had a similar problem with my GMC Sierra.
it turned out to be the "spark control unit " located on the back of the distributor.
I haven't worked on Fords in a long while until recently, so im not sure if your Ranger has a comparable part.

It gets warmed up and shuts down. It is testable at Autozone.

 

Rangers didn't have a separate spark module from 1995 and up, thats when the got they larger computer, EEC-V
But the 1994 and earlier did have that issue of spark module heating up and shutting down or misfiring

 

Got FORscan loaded on my computer and read the codes with the ELM. Hopefully this provides a bit more information for you all.
Thanks again!

*** I should add that the truck is not currently starting/running and there is 12V at the red wire on the injectors.

 

Still pulling my hair out.
At the insistence of an "older" person we replaced the fuel pump. Now it won't start - ever. At least before it would start and run for a while but then die.
Here is the latest code pull.


P1000 - ODBII Monitor Testing Incomplete
P1808/P0804 - 4WD Low Indicator/High Indicator Open/Shorted to Ground
P0500 - Vehicle Speed Sensor Malfunction
The B codes seem to deal with mostly lamp circuits except B1352 which is Ignition Key In circuit Failure. (B1318 is battery low voltage - it's on a charger now)
So we don't seem to be any further ahead. Anyone have any other thoughts?
At this point we have a new fuel pump (can hear it running) with new pump filter.
Thanks in advance.

** Quick addition. I've seen many threads related to the PATS going bad. This doesn't look like it from my understanding but hey, what do I know...could that be the issue?
Also, I've seen a lot of inertia switch issues...possible the issue here? How do I check that.

 

P1000 just means battery was unhooked, it goes away on its own after driving a week or two

None of the other codes can prevent startup

Do you HEAR the fuel pump run with key ON, it only runs 2 seconds, and is not quiet, and it runs for 2 seconds EACH TIME key is turned from off to on, can't over pressurized it, just keep trying and fixing until you HEAR IT

If you can crank the engine using the key then PATS is not the issue
"Theft" light on dash will flash rapidly with key on, if PATS has disabled startup

Unless its a Motorcraft fuel pump, "new" just means never EVER tested, so can be dead out of the box

 

Yes I definitely hear the pump turn on every time the key is turned to on - much easier to hear with the bed off. It runs about 2 seconds then turns off. Does it every time.
I didn't really think it was PATS but thought I should ask.
Interesting that it doesn't start at all now though. I'm thinking it's "coincidental" but odd none-the-less.
I'm trying to find NOIDS or a scope so I can see what's happening on the injectors when its turning over. I did measure +12V there, just not sure what's happening during cranking.
I think I've ticked the list you provided....any other ideas?

 

Spray fuel into the engine, 50/50 test
Try to start engine
If it starts and dies then spark is OK but no fuel from injectors
If it doesn't start then spark is your problem
50/50 instant results

From a lawnmower to a V12 Lamborghini, there is no better gasoline engine test

If you are old enough you may have seen these at a Mechanic's shop: https://cdn1.mecum.com/auctions/fr01...?1547070676000
They would be on a rolling cart
Open the hood, wheel it up so customer could see this was a PRO....fessional shop, "we test.........not guess"
Then reach under it on the top self for the Ether(starting fluid), spray some in.....................

 

Yup, did the 50/50.
So we did it initially (when this challenge started) and it would start up every time after it died.
Wisdom said change the fuel pump...we did.
We can hear it run every time but now the truck won't start. Sprayed starting fluid in the throttle body and it still won't start.
Have some NOIDs coming next week. We'll see what's happening with the injectors then. I'll also do another fuel pressure test then to make sure we are getting the expected pressure.
I'm guessing there is something that was on it's last legs and "coincidentally" it gave up the ghost when the pump was replaced - just speculation on my part.

 

I had this same problem with my 99 4.0. Turned out the starter was bad but it bench tested good under load. Mine is getting a rebuild because right after the mechanic got the starter replaced and verified it would run, he cut it off due to how bad it sounded. Turns out the oil pump apparently failed at the same time as the starter. Rebuilding with new parts due to not knowing how long the oil pump was out.

 

Well if it didn't start/fire with 50/50 test then you KNOW its spark or compression issue, period, not a fuel issue

Spark module is IN the computer, only external components are the Coil Pack and Crank sensor
Coil packs have 3 coils inside, likelyhood of all 3 failing is remote, 1 maybe, so engine would still fire, unless coil pack doesn't have 12volts with key on, easy to test that

Crank sensor is the ONLY sensor that can cause a No Start
Computer has no connection to Starter Motor activation
It will start spark, and fuel injectors, ONLY when crank sensor sends the computer a good Timing Signal, so no timing signal = no start

You have a CEL(check engine light), it will come on with key on, means computer has booted up
CEL should go OFF as soon as engine starts to spin, that means computer is getting a good Timing Signal from crank sensor, if CEL stays on then NO SIGNAL from crank sensor

 

Ok, after a week away we're back and doing more testing.
Fuel Pump: I checked the fuel pressure. It came up to 65-ish lbs and stayed there during the entire time we fussed with the truck.

The truck ran for quite a while. We got tired of waiting for it to die, so we turned it off after a few minutes. We couldn't initially get it restarted. Then it would alternate between starting and not starting.
While running, I had an oscilloscope connected to a fuel injector to watch for the voltage pulses, definitely there. (Screen shot attached)
When the truck would not start there were no pulses at all, completely flat line.

I also checked the coil pack, there was 12V there the entire time the key was on.
Crank sensor is new - it was the first thing we replaced at the start of all this so it should be good to go. (CEL goes on when cranking).

So....does this mean we are at the computer? If so, where is it so I can pull it and do at least a visual inspection on it.
Thanks again!
Wayne.

 

Computer is in engine bay on upper firewall, passenger side center, large 104 pin connector held on with a bolt
Disconnect battery first then remove comnnector
Then two nuts on the computer case and it will slide out

Open it up and have a look

 

It's clean...very clean.
Any other options to confirm it's the PCM before beginning the search for another one?

 

No, not really

There is no PCM test

You can check car-part.com: https://www.car-part.com/

1999
Ford Ranger
Computer box engine
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Select your model, 4.0l AT(automatic), you should see the XL5F-(12A650)-XX or XXX on your computers label, the XX/XXX is the software version, good to match
Federal emissions was what most Rangers used, Calif used Low Emissions
2WD or 4x4 doesn't matter to computer, just engine size and transmission type
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You need the computer, the PATS module above the glove box, and the matching key WITH ignition cylinder, its all plug and play, if you get all 3 things
Computer and PATS module are matched pair
Key's transponder number is programmed in to PATS module

 

So some of the places sell lifetime PCM's programmed to your VIN. Does this mean I don't need to source the ignition or PATS module?
Assuming that's the case then I need to find keys (none of the places I've called so far have a "full set" - PATS, PCM, ignition and keys.) It looks like keys are available which can be cut to match the ONE key I have. Will I be able to program the new keys since I have only one right now? I do have FORscan.
Thanks again.

 

The saga continues.
After a long search including the links you had sent I ended up buying a refurb, lifetime warranty ECM. They programmed to my VIN. (Verified to my VIN through Forscan)
It has been installed.
I got the extended license for Forscan so we can program keys into it. We bought 2 new keys to be programmed in addition to the original (not OEM key).
After trying to program the keys several times, I simply get a "programming failed" message every time.
I put the key in (all 3 do this) and the motor will turn over but not start.
The theft light is flashing rapidly. After a minute or so it does a 1 6 flash which according to a different post you've said is a CAN communications error.
Where the heck do I go from here??
I want this thing outta my garage and my son wants his truck again.
Any help is appreciated.
Thanks!
Wayne.

 

16 means the PATS module can not "talk" to the PCM, unique to 1999/2000 Rangers in that the PATS module is separate unit, in 2001 it was inside the PCM

When the truck was built Ford "married" the PATS module and PCM, this means each was programmed with a Private Codes(see RSA encryption) so they could "talk" together and so PATS module could tell PCM, "OK TO START" if key passed the test

New PCM won't understand the PATS "OK TO START" message, code 16

Forscan may be able to "re-marry" the PATS and PCM, Ford can, its a long process, takes 45 to 60 min just because a thief could do it and thats just too long to hang around to steal a vehicle, lol

But you should still be able to program keys, I thought key's RFID numbers were stored in PATS module, but they may be stored in PCM, if thats the case then with code 16 it can't store the new key RFID numbers
PATS is a proprietary system for obvious reasons, any anti-theft system is, so all we really know is what comes from post and eye witness accounts of what works

In 1999 PATS didn't always disable starter motor

In the diagram the 2 wires on 5 and 6 are the data wires to PCM, could be one is broken, extreme longshot

 

Thanks for hanging in there with us RonD.
So, why do they advertise programming the ECM with your VIN if that doesn't address the married to the PATS module issue? I would have thought that would have also put that programming into it....apparently not?
I'll check the wires but doubting thats it as it did start before and we never had the flashing theft light.
Guess i'll start looking into how to program the ECM for the PATS module now...sigh, thanks Ford, this never ends.
Would have been very nice to find a complete ECM/PATS/ingnition/keys setup. You'd think the parts recyclers would have figured this out by now. Spent 2 weeks and called dozens of recyclers and they all will sell you a stand alone ECM but sound confused when you say you want the whole system....sigh...guess we do this the hard way.
Thanks again.