Random Stalling While Driving

[shr3dd3r 09]

Since completing my 5.0L swap in my 2000 Ranger 4x4 in January, I have finally gotten it tuned right to run with my m5r2 manual tranny. It runs great except for one frustrating and potentially unsafe problem... it shuts itself off randomly. This is going to be a long post so I can adequately describe the problem and list all the crazy things I have done in the hopes of stopping it. Here goes...

The problem:

Usually, though not always, my truck will stall once it has warmed up. Generally it will lose power briefly, almost like it is losing fuel pressure or misfiring, and then it will pick back up in a split second and run fine. But then, at random and completely independent of engine load it will just die out of the blue. No sputtering or anything, just dead. When it does die, if I try to start it it will just crank. The fuel pump continues to run after it dies until I turn the key off.

However, if I turn the key off and then back on it will fire right up instantly and run for who knows how long until it dies again randomly. Occasionally it will spit some black smoke, like it is dumping too much fuel into the cylinders at random times. It is not burning oil. So I don't know if it is flooding itself out or what. Also, it does seem like it cranks a little longer than it should upon start up.

At one point it threw a p1356 code and a p1451 code. Canister vent solenoid malfunction and PIP signals present with engine not running. These codes were cleared and they have not shown up since, even though the problem persists.


What I have done:

Replaced fuel pump.
Replaced fuel filter.
Replaced camshaft position sensor.
Replaced crank position sensor.
Replace one coil pack that had a bad connector.
Checked all associated circuits.
Inertia switch is good.
Fuel pump relay is functioning as it should.
All of the grounds appear to be undamaged.
MAF sensor is clean.
Throttle body is clean.
No vacuum leaks.

I checked the pressure regulator on the fuel rail by removing the vacuum line to see if any fuel was present. There was not. Also, the fuel pressure remains high for at least 30 minutes after shutdown, so I assume the pressure regulator is working as it should.

I even hooked a volt meter to the fuel pump power wire and waited for the engine to run long enough to stall. Even when it sputters or dies completely the fuel pump is getting consistent power to it. At the fuel rail it holds steady at 57psi. The pressure does drop when the stumbling or dieing occurs, but the pressure jumps right back up immediately even after it dies.

None of the above attempts have solved the problem. I don't know what else to check, and I am very tired of throwing money at it at this point. I don't see why the tune that is on it would cause it to die at random, and I find it difficult to believe that the computer is all of a sudden malfunctioning. This problem has only been present for the last 3 weeks or so. I am extremely frustrated at this point after trying everything above.

Any help or advice would be greatly appreciated. It is my daily driver and I really don't want to lose my power steering at an intersection.

 

[LIMA BEAN]

Man sure sounds like a ground. ECM's are funny they dont like gray and freak out when all else is good. Make dam sure it's grounded good or it will fuss you to death. Good luck and let us know.

 

[morse johnson]

i had the same problem with my f150 what i found out was that my hot wire that goes to the starter was getting very hot from the headers it was to close. Now what i did to fix it was rerouted that big red wire and that took care of everything.

 

[shr3dd3r 09]

After an incident today I am leaning toward the fuel system being the problem. It was flooded today and when I started it it poured black smoke and wanted to die. I sat there and feathered the throttle for a minute or so until the smoke dissipated, and then it drove just fine. Either the FPR is bleeding fuel through the vacuum line, one or more injectors are leaking, or my computer is just going haywire....Or something else. I have no clue at this point.

Yet while driving it will just die randomly with no noticeable cause. Could a sudden fuel dump cause this kind of instant stalling?

What do you all think? Could any of these issues cause completely random stalling while driving?

 

[RonD]

The fuel pressure dropping could mean the PCM is opening all(most) of the injectors at once, flooding out engine, then closing them once the CKP stops sending a pulse, engine has stopped, so pressure returns.

I read it somewhere that a PCM would fire multiple injectors as a "get you home" default if a problem was detected.

You could put some Noid lights on the injectors and see if that is happening when it starts to die.

EDIT:
You mentioned a vacuum line and FPR, which a 2000 Ranger wouldn't have, and then fuel pressure above 55psi which the newer(1998+) Fords have switched to, a returnless fuel system, FPR is in the tank with the higher pressure pump.

The pre-1998 Rangers had the FPR on the rail with vacuum line and tank return line, and ran fuel pressure between 30-40psi.

So does the 5.0l have an FRP with vacuum line on the fuel rail, if so how did the return line get connected, as the 2000 ranger didn't have one?

 

[shr3dd3r 09]

The fuel pressure dropping could mean the PCM is opening all(most) of the injectors at once, flooding out engine, then closing them once the CKP stops sending a pulse, engine has stopped, so pressure returns.

I read it somewhere that a PCM would fire multiple injectors as a "get you home" default if a problem was detected.

You could put some Noid lights on the injectors and see if that is happening when it starts to die.

EDIT:
You mentioned a vacuum line and FPR, which a 2000 Ranger wouldn't have, and then fuel pressure above 55psi which the newer(1998+) Fords have switched to, a returnless fuel system, FPR is in the tank with the higher pressure pump.

The pre-1998 Rangers had the FPR on the rail with vacuum line and tank return line, and ran fuel pressure between 30-40psi.

So does the 5.0l have an FRP with vacuum line on the fuel rail, if so how did the return line get connected, as the 2000 ranger didn't have one?

You are correct. It is a returnless fuel system. What I was describing was the fuel rail pulse damper, which is a little regulator that sits on the fuel rail near the firewall. It has a vacuum hose on top of it that runs directly into the intake. If the pulse damper fails, gasoline can be sucked through the vacuum line into the intake.

If the pulse damper is not doing its job, then when the engine is off the fuel pressure can bleed off through the vacuum line and wash the cylinder walls with fuel. Hence the flooding on start up.

This is my theory, but I'd like more opinions and advice. In any case I have no idea how to replace that sucker without removing the intake and fuel rail. So I could use some advice there too if that is what needs to be done.

By the way, I checked the grounds today and they are all good.

 

[ericlerouge]

Sure sounds like a vapor lock problem to me. If i were you, i'd remove the gas cap and take a drive until everything is hot. Now, i don't know how a system works without return line. but it seems to build up vapor somewhere in the fuel "return device" or even in the tank.

 

[RonD]

Yes, forgot about that vacuum line.

Noid light then, see if injector is pulsing or solid ON when engine stumbles.
If so it could be injector wiring, on my 4.0l there are only two grounds from the PCM, so PCM fires 3 injectors at one time, a short to ground on one or those wires would hold open 3 injectors.
I found an electrical diagram for a Ford 5.0l, that was firing 4 injectors at a time so 2 ground wires, but then another later model 5.0l that had 8 grounds from the PCM, so one per injector.

Or could be PCM, if Noid light stays on.

If Noid light stays on so injectors are stuck open, unplug the PCM module if light doesn't go off, if light goes off then PCM is the ground, if light stills stays on the short in the wiring is the ground.

 

[shr3dd3r 09]

Tried driving with the gas cap off. No luck. Same problem. I don't think my problem is vapor lock. I don't have a set of noid lights either, so I have reached the limit of my troubleshooting capabilities.

I think the best thing to do at this point is take it to my tuner and have him data log it to see what exactly is happening when it loses power and go from there.

Could be the computer, the tune, wiring,or injectors, or none of these. I don't know. Hell maybe it's low on turning signal fluid...

 

[RonD]

The "low turn signal fluid" light should come on if that was the case, so must be PCM issue.

 

[shr3dd3r 09]

Found the problem and fixed it. Guess what it was? The canister purge valve solenoid was bad. As a last ditch effort I replaced it with one from a friend's Mountaineer and now it drives great and has more power. I had no idea that would cause completely random stalling. My truck was a 3.0L flex fuel, so I replaced the valve with one from a 5.0 mountaineer, but they look the same except for the mounting holes. In any case the problem is fixed thank God.

 

[RangerSVT]

I would go back and see Gregg and remove those emissions solenoids from the ECU, as I have...

SVT