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stalling problem every few days

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1997 ford ranger. intermittent problem. happens every few days.

truck stalls. can be on the interstate or idling in a parking lot, doesn't matter.

runs rough for a few seconds, then stalls. might cough and pop, then starter cranks engine very easily as if no compression. will not start at all.

only have to wait 5-10 minutes, then starts up completely normal as if nothing happened. runs fine.

this started well after the check engine light came on last month. when this stalling problem started happening, got the engine codes and they said "running lean"

got a new O2 sensor. disconnected the battery during replacement, that cleared error codes. check engine light turned off.

light still off, but this problem still happens. must not have anything to do with the check engine light.

AutoZone says it's not the O2 sensor or Mass Airflow Sensor, because that wouldn't cause an intermittent problem. also rules out the fuel filter and fuel pump. doesn't know what intermittent problem could occur days apart.

the strange thing is, this all started when flushing the radiator. did it every few minutes (ran rough, stalled, died, wait a few minutes to start again) then after finished putting in the antifreeze it does it every few days now.

what could it be?
 


enjr44

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Wiring or grounds or vacuum line would be my guess? Something you disconnected, reconnected, messed with when you changed the coolant?

The o2 sensor was probably OK, it was try to tell you that there was too much o2 in the exhaust. So a disconnected vacuum line would fit.
 

RonD

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"Lean codes" don't mean engine was ever running lean, just FYI
Computer codes hardly ever mean what you think, they are written in yes/no logic, computerese.

What the lean codes mean is that the computer is having to add more fuel than it has expected in its calculations.
MAF(air flow) tells computer how much air is coming in, computer then calculates fuel needed for that much air based on 14:1 ratio, after fuel is burned it looks at the O2 sensors oxygen levels, if they show too much oxygen in exhaust then computer adds more fuel, opens injectors longer.
Computer keeps track of this by Short term fuel trim(STFT) numbers.
0 fuel trim is the 14:1 ratio calculation
-1 fuel trim means computer is adding less fuel, not opening fuel injectors as long
+1 fuel trim means computer is adding more fuel, opening injectors longer.

When fuel trims get down to -15 or up to +15 for any length of time computer will let driver know that its calculations are wrong.
+15 would be the lean code.
Engine is not running lean computer is still adding the extra fuel to keep O2 oxygen level within parameters, the code is to let you know something is off.

If engine was blowing extra smoke, running rich, or was pinging/knocking, running lean then O2 sensor could be the problem, because it is feeding the computer the wrong info.

Generally Lean Code would be that not all the air coming into engine is passing thru MAF sensor, so computers calculations are based on faulty info, vacuum leak.
But low fuel pressure would mean less fuel is flowing to injectors so same +15 fuel trims because of that.

Engine stalling could be Fuel pump relay opening causing fuel pump power to be cut, that would also generate Lean code over time because as fuel pressure dropped +15 trim happens.
Fuel pump relay can be intermittent and is only $7 so I would replace it on spec. may not be the problem but $7 takes it off the table, could still be relay wiring issue but............

What you could do is to locate the Schrader valve(looks like tires air valve) on the fuel injectors rail, this is there to test fuel pressure.
Next time engine stalls for no reason pop the hood and test if fuel rail has pressure, you don't need a gauge, just push center pin like letting air out of a tire, but BE CAREFUL, there should be 35psi of pressure in there so fuel will spray out, have a towel handy :)
If there is little or no pressure then fuel is the issue, it is being shut off for some reason.

If there is lots of pressure and engine still doesn't start then I would have a can of Quick Start(ether) handy, pop off Power Brake Boosters hose and spray some into intake, put hose back on and try to start.
If it fires up and dies then injectors could be off.
If it doesn't fire then spark is what you are losing.

On the Lima 2.3l engine there are dual spark plugs and coils.
But only the Exhaust side spark plugs/coil are used when starting, intake side spark plugs/coil don't come online until engine is running.
 
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Wiring or grounds or vacuum line would be my guess? Something you disconnected, reconnected, messed with when you changed the coolant?

The o2 sensor was probably OK, it was try to tell you that there was too much o2 in the exhaust. So a disconnected vacuum line would fit.
I didn't disconnect anything when flushing the coolant. a vacuum line may have come off (it's an old truck) but wouldn't that be a constant problem and not intermittent?

"Lean codes" don't mean engine was ever running lean, just FYI
Computer codes hardly ever mean what you think, they are written in yes/no logic, computerese.

...

Engine stalling could be Fuel pump relay opening causing fuel pump power to be cut, that would also generate Lean code over time because as fuel pressure dropped +15 trim happens.
Fuel pump relay can be intermittent and is only $7 so I would replace it on spec. may not be the problem but $7 takes it off the table, could still be relay wiring issue but............

What you could do is to locate the Schrader valve(looks like tires air valve) on the fuel injectors rail, this is there to test fuel pressure.
Next time engine stalls for no reason pop the hood and test if fuel rail has pressure, you don't need a gauge, just push center pin like letting air out of a tire, but BE CAREFUL, there should be 35psi of pressure in there so fuel will spray out, have a towel handy :)
If there is little or no pressure then fuel is the issue, it is being shut off for some reason.

If there is lots of pressure and engine still doesn't start then I would have a can of Quick Start(ether) handy, pop off Power Brake Boosters hose and spray some into intake, put hose back on and try to start.
If it fires up and dies then injectors could be off.
If it doesn't fire then spark is what you are losing.

...
"running lean" codes might have been generated when it stalled and trying to start the engine... so the "running lean" wouldn't have anything to do with the actual problem. that's one possibility.

I knew about checking the Schrader valve, but I couldn't find it. where is it located?

isn't starter fluid bad for fuel injected motors? why would I take off the hose to the brake's master cylinder for that?
 

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If you used enough gasoline OR ether in an engine it could wash the oil off cylinder walls, but other than that is it safe to use, but ether IS inflammable(burns easily, much easier than gasoline) which is why it is prefect for a Starting Fluid :), so be careful around hot "stuff" with it.

Don't have a 2.3l but in this video, about 1:30 in, it shows schrader valve at the front of the fuel rail: https://www.youtube.com/watch?v=poS2K9VdTR8


Would be lean codes just before or when it stalls, once engine is off computer doesn't use O2 sensors for at least 1 minute after starting, so cranking engine with a no start wouldn't effect fuel trim numbers.
O2 sensors need to be above 600degF to work properly so computer ignores them for a minute or two after starting or for upto 5 minutes as cold engine warms up, this is also why they are heated, to warm up faster.

Computer runs 14:1 mix based on Long Term Fuel trims(LTFT) during this time, computer is said to be in Open Loop when O2 sensors are not working, LTFT are averages the computer saves in memory, these are needed since as an engine gets older things change, fuel pressure goes down, MAF gets dirty, compression gets lower, all normal wear and tear, so computer biases the 0 fuel trim calculation with a + or - fuel trim from LTFT data.
When O2 sensors are working computer is said to be in Closed Loop
 
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PurpleFluffer: the strange thing is, this all started when flushing the radiator. did it every few minutes (ran rough, stalled, died, wait a few minutes to start again) then after finished putting in the antifreeze it does it every few days now.

Did you 'wash' anything you might not have wanted when flowing the water for the flush? Is it possible the coolant temp sensor got overheated due to low coolant(water/antifreeze) in the engine?

An engine that is running, starts to stumble, shake, and 'slow down and die' indicates that it is either 1)losing fuel supply, 2)getting fed bad fuel, 3)losing spark, 4)having the computer fail to note the lowered rpm and bump the IAC or 5)the IAC is doing its thing but the engine is dying anyway.
You can bypass the IAC by moving the mechanical stop on the throttle body to crack the throttle plate open even when the IAC is disconnected. Mechanical idle control.
You can check that you continue to have spark from the coil(s) by putting a spark tester in-line with the spark plug and observing that it has spark or not.
You can check the fuel situation by spritzing fuel into the intake.

The power brake hose is just a convenient and large sized hose that provides access to the intake manifold. If you squirt gasoline or ether or carb cleaner into the power brake vacuum line, it will get sucked into the intake and fed to the cylinders. If you have a lack of fuel problem this will provide fuel and make the engine run.
I would be checking there is not some connection that gets poor when the engine gets hot. The coil mount could be bad, or the grounds, either could cause stalling, but more likely a 'quick stop' as ignition is removed, or a bumbling stall as the power/ground to the ignition comes and goes.
tom
 
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found the Schrader valve. waited for it to happen again.

did it today, quite severely. (wouldn't start for a long time) left the ignition ON to make sure the fuel pump didn't get turned off. checked the Schrader valve, a little fuel dribbled out and stopped. no spray or anything requiring a towel. or a napkin. maybe a q-tip.

that means no fuel.

dude at AutoZone recommends using a fuel pressure gauge to check pressure even when this isn't happening. may be a good idea but I don't want to go through all that. yet.

someone else said the problem could be the fuel pump relay. dude at AutoZone said I could try swapping that relay for a different one (air conditioning, for example) and see if the problem persists or if it makes problems with the other circuit instead.

no, nothing got 'washed' when changing the coolant. normal hosing on the radiator.

some part getting hot isn't the problem, because it drives several days with no problem.

will see how it goes today.
 

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Just FYI, computer turns on fuel pump for 2 seconds when you turn on the key, then it stays off when engine RPMs are below 400, after starting and RPMs are above 400 then computer turns on fuel pump again and it stays on.
This 400rpm thing is a safety feature in case a fuel line breaks or ??, so when engine stalls computer turns off fuel pump, to prevent possible fire or ?? if gas continued to pump out.

So key on or off wouldn't matter for your test for pressure after engine stalled.

So assuming schrader valve isn't clogged up, lol, problem is fuel pressure is lost while driving.
Yes, could be fuel pump relay and swapping it with WOT(wide open throttle) relay would be fine, same relay.
WOT relay turns off AC when your foot is to the floor.

Next thing I would do would be to get a 12volt test light.
In the cab, passenger footwell, is the inertia switch, usually just above carpet under glove box, small box with 2 wire connection, and a reset button on the top, inertia switch cuts fuel pump power in case of a sudden stop(accident) or roll over.

Hook up test light to either of the 2 wires on inertia switch and the other test light wire to a Ground.
Turn on key and you will see test light come on for 2 seconds then go off.

Now drive, light will be on as long as engine is running, if it should go out while driving then engine will stall soon after and you will know it is fuel pump relay OR wiring from relay to inertia switch.

If light stays on and engine stalls then fuel pump is most likely bad.

Knowing that the fuel pump comes on with the key, do you hear the fuel pump when key is turned on, fuel pump is not quiet, makes a distinctive hum?
Turn key on and off a few times and listen.
 
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roger that. fuel pump turns off anyway when RPM's below 400 (i.e. stalled) so it won't have fuel pressure.

Schrader valve not clogged. tried it with engine running, got a good squirt.

connected fuel pressure gauge to test under normal running conditions, got 60 PSI at idle, 58 PSI at hi throttle. within spec.

listening for the fuel pump. when turning on the key, I don't hear anything. (but it must be working, because it starts) Haynes manual says you might try removing the gas cap, put your ear to the filler hole, and have an assistant turn the key. don't have an assistant, will try using a 6' hose and listen thru that.

when I can successfully hear the fuel pump, that will help a LOT next time it starts acting up. instead of cranking and wasting battery for no reason. even if I look like a weirdo stalled on the interstate with a garden hose going from the gas tank to my ear.

will find location of fuel pump and WOT relays and swap them tomorrow.

"If light stays on and engine stalls then fuel pump is most likely bad."

I thought the fuel pump either works or it doesn't? doesn't have intermittent problems.
 

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The fuel pump can be intermittent...I know this for a fact...and it can wonk out on you at any time, but mine seemed to only do it on days when there was a wild fluctuation in temperatures...like fall days that are warm and nights are cold...it won't wonk out in the cold so much as the warmer part of the day...

So think back over the time that this has been happening...if it is the fuel pump...and the temps have fluctuated more than 10-15 between day and evening temps...or even morning to afternoon...especially in those times, actually...
 

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It WILL have fuel pressure after a stall UNLESS fuel pump was shut off earlier causing the stall.

Fuel injected engines hold fuel pressure in the rail for months and months after being parked/stored.
Your year should have 35-45psi when running and above 28psi after shutting down engine.

Fuel pressure regulator(on fuel rail) holds pressure at around 40psi, fuel pump has a check valve(flap) so fuel can only flow out of the pump not back in.
When when you turn off the key the fuel injectors stop opening and the fuel pump stops pumping, so pressure should stay at about 30psi.
If pump should stop earlier then injectors keep working and pressure drops until engine stalls.

As mark_88 said a fuel pump is an electric motor, so it of course can be intermittent.

Try letting the gas tank get down to 1/4 or less, will make hearing the pump easier.
Although if I listen I can hear it with a full tank
 
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it's a 99. 56-72 PSI.

tried the garden hose. works excellent. will take it with me driving around.

swapped relays.

waiting for it to happen again...
 

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RonD:Fuel injected engines hold fuel pressure in the rail for months and months after being parked/stored.

I would not rely on that as an affirmative test, but the system should hold pressure for a bit of time after the pump runs at key ON and shuts off. If it has a very broken regulator check valve, or bad fuel pump check valve,(or leaky injector) depending on return or returnless system, it may become difficult to start. If it can hold pressure for a minute, say, it should start normally. At least I'd expect that. A loss of pressure over time is normal.
OTOH, some systems, such as Mazda, as used in the Probe 2.5l v6, do NOT prime the FI system, and the pump will not run at key ON. Fooled me for hours on that one until I found out, chasing a fuel pump problem that did not exist.
tom
 

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RonD:Fuel injected engines hold fuel pressure in the rail for months and months after being parked/stored.

If it can hold pressure for a minute, say, it should start normally. At least I'd expect that. A loss of pressure over time is normal.
OTOH, some systems, such as Mazda, as used in the Probe 2.5l v6, do NOT prime the FI system, and the pump will not run at key ON. Fooled me for hours on that one until I found out, chasing a fuel pump problem that did not exist.
tom
Tom, just a question about the Mazda thing. If the pump doesn't come for the first time on until after the engine is running. And losing pressure over time is normal, how does it ever start after sitting? I thought you needed pressure at the injectors to get fuel into the engine. Just curious. :popcorn:
 

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I don't remember for sure, but it might be that it is enabled whenever the crankshaft or camshaft is turning. It just does not have the 'prime' 3-5 second run at key ON.
Some cars used to depend on the oil pressure sending unit switch to enable the fuel pump(chevy vega with 2300 back in the 70's.), so the engine would stop if the pressure fell off too far. Weird way to prevent damage, I think. Or maybe it was the other way around, and was to stop the pump if the vehicle flipped, and oil pressure fell... oops.
I am pretty sure the 2.5 engine uses pulses, possibly distributor feedback (think tach) to indicate the engine is either 'running' or 'turning'. That engine is nice, but today there are a lot of nice dohc V6 engines on the road. If you poke on the web, you can find how that engine was designed, and some of the looooong term tests done. Like the duratech, that engine is able to go hundreds of thousands of miles will little to no wear, given reasonable maintenance.
tom
 

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