2002 Explorer 4.6L long crank time to start

[ab_slack]

Out of the blue my 2002 Explorer with 4.6L is taking awfully long to start. Normally just a couple seconds and it starts right now. Now it takes a pretty consistent 15 seconds of cranking before it starts.

Battery seems good and it cranks well the whole time. Once started it shows no signs of any other problems.

Any suggestions where to start to find this?

My only guess is that the fuel pump isn't starting right away or it taking time for fuel to fill the line.

Any help appreciated.

Thanks in advance.

 

[Catterman]

3 things to check from my NON professional knowledge...

1) Fuel Filter
2) Fuel injection pressure regulator
3) Fuel pump - this is probably what it is IMO...

 

[Lost Bushman]

3 things to check from my NON professional knowledge...

1) Fuel Filter
2) Fuel injection pressure regulator
3) Fuel pump - this is probably what it is IMO...

This.

 

[RonD]

Try this next time you start it:
Turn key on, count to 3
turn key off
repeat 3 times
(Ford Computer runs fuel pump for 2 seconds each time key is turned on, so you are building pressure if it was lost)

Then crank engine, if it starts right up then you have a pressure leak in the fuel system.

Could be an injector or fitting leaking but you would probably smell gas after shutting off engine.
The '02 has returnless fuel system but has a check valve on the fuel pump that holds fuel pressure when pump is off.
If that valve is leaking then pressure would be lost after sitting for a bit, no gas smell because gas is just returning to the tank.

The fuel rail pressure on the returnless system runs about 65psi, it has no "regulator", just a damper to take any extra pressure spikes when fuel pump comes on.
The computer has no way to monitor fuel pressure, it just assumes 65psi, the computer turns on the fuel pump for 2 seconds at startup, then doesn't turn it on again until engine starts, RPM above 500, or if the key is cycled off then on again.
The computer uses engine RPM, vehicle speed, throttle position and Air flow(MAF sensor) to determine when to turn the fuel pump on again.

Does time matter?
i.e. if you shut off the engine and restart within 10 minutes does it start right up
Do you only notice long crank time after sitting for several hours?

Does temperature matter, cold out or warm out?
Does engine temp matter?


Fuel filter issues are usually noticed at highway speeds first, as filter gets "clogged" there is less fuel available so a lack of power when maintaining higher RPMs

 

[adsm08]

Probably a bad anti-drain back valve in the pump. It is letting the fuel drain back into the tank after the pump shuts off.

Check fuel pressure bleed off. Hook up the gauge, cycle the key a few times to get max pressure, and then shut it off and watch it drain back. It shouldn't go below 25 to 30 lbs.

 

[ab_slack]

I hadn't driven it for a couple days. Yesterday I went to check a couple things.

Specifically put a gauge on and see what the fuel rail pressure was doing with time see if there was a connection. When I went to move it to a better spot to work on it, it started right up and I had absolutely no problems with it all day.

This morning I started it up and it took a few extra seconds but not as bad as it had been nor perfect like yesterday.

Then after driving it to the store, 20 minutes later, it took a long hard 10 seconds cranking to re-start.

Good suggestion there Ron but the multiple key-on before cranking.

I mostly don't want to get stranded someplace with it which is my big concern at the moment.

 

[ab_slack]

Probably a bad anti-drain back valve in the pump. .

Would that require a pump replacement? Or is anti-drain back valve be something that is replaced separately?

Vehicle has 192K miles.

 

[adsm08]

Only as part of the pump.

 

[ab_slack]

Had a few minutes today and since it was happening I put a pressure gauge on the fuel rail.

Pressure while operation sits right on 65psi as Ron Mentioned.

When I turn off ignition pressure bleeds down fairly quickly and is against the bottom pin of my pressure gauge (<5psi) in about a minute.

Doing the key on for 3 seconds, cycle off and repeat on for 3 seconds as Ron suggested, if I left it sitting some time, I could key it on three times without seeing any movement of the pressure needle. Sometimes just a little movement at the end of the third. It varied depending on how long I waited.

I am not smelling any fuel.

Not sure if these observations narrow it down to fuel pump verses a leaky injector. Somehow I think, if it were injector, pressure would bleed down and pressure would come back up quicker. So I am thinking it is the fuel pump.

 

[RonD]

Well....good info there.

But, not sure on that pressure reading, I would retest and make sure gauge is tight.

Here is my issue, if pressure is dropping that fast with engine off then getting to the 65psi would be very hard since pump isn't on all the time while engine is running, so you would have seen a swinging pressure down to maybe 30psi and then up to 65psi again with engine running, not a steady 65psi.

Cranking the engine for 10 or 20 seconds doesn't turn on the fuel pump again, turning key off and then on again cycles the fuel pump.

So why would it start after 10 to 20 seconds of cranking?
Two or three times cranking yes, because fuel pump cycles on each time.

Just puzzled with the pressure gauge readings

Could be the fuel pump check valve(back flow), just seems to drop pressure too fast, and then not recover as it should with key on/off cycling.

 

[ab_slack]

Always a possibility I didn't get it on tight enough. I did check for leaks when I started the engine the first time. I've used the same setup with the B2 and the Jeep and those held steady. Doesn't mean it couldn't have been loose.

Now that is a good point about pressure holding steady when running. I really didn't look at it very long running, I am thinking I saw it over a 20 second period and looked solid. In fact, while it took almost a minute to drop to the bottom of the gauge, it took less than 10 seconds to drop to 30 PSI. Thus I would have expected it to be moving quite a bit. Possibly my observation in that regard was faulty.

As far as the question about why it should start after extended cranking, I have to assume that the full pump runs when ignition is moved from the run to crank position. That while it only runs 3 seconds to "prime" the system (that my understanding) when first turned to run, that when advanced to crank it must run the pump. Otherwise if the 2-3 second pump run time weren't sufficient one could crank forever and it would never start.

For what it is worth, when cranking, it would start to catch when PSI on the gauge got up around 10PSI.

 

[RonD]

Yes, I would retest, it would be running very lean on cold start at 10psi

 

[ab_slack]

Yes, I would retest, it would be running very lean on cold start at 10psi

I should clarify, I see it hitting 10 PSI it goes from cranking without any sign of catching. It hits 10 PSI within a fraction of a second after the first movement of the pressure gauge.

As it catches it jumps up to 65 PSI within a second.

 

[RonD]

Sorry it took a year to reply............

Happy New Year

Boy, that is weird, 10 to 65, can't see fuel pump issue, even check valve issue would be hard to diagnose from that.
Just because it is easy, at the end of the fuel rail there is the Pulse Damper, it will have a vacuum line attached, pull that line off and smell it foe a gas smell, it should not have a gas smell.

Another thing to try, Computer controlled engines have a WOT(wide open throttle) routine for startup.
When gas pedal is pressed to the floor the TPS(throttle position sensor) is sending max voltage to computer(above 4.5v) this tells the computer to disable fuel injectors while cranking engine.
This routine is there to clear a flooded engine.

So next time you try to start cold engine or warm engine for that matter, before turning on the key, push gas pedal to the floor and hold it there while cranking, engine should NOT start since no fuel will be available.
If it fires a bit then there is fuel available in the manifold, where it is coming from???

And just to confirm normal startup, besides the long crank time:
When key is turned on a few things happen:
The IAC(idle air control) valve is opened all the way
Fuel pump comes on for 2 seconds
ECT(engine temp) sensor is checked for cold or warm engine

When you start cranking:
pulses come from crankshaft sensor
there is about a 1-2 second delay, after pulse is received, before spark and fuel injectors are started, this is "said" to be done to pre-lube engine, if they were worried about that why not just add a pressure sensor to oil passage, lol, oh wait they already have one.
anyway once engine starts RPMs should go up to 1,500+, IAC valve is open all the way
computer then closes IAC valve to set idle at 1,000rpm cold or 750rpm warm
So idle should drop after startup

Does your system work that way?

 

[ab_slack]

You got your post up while I was re-checking. Today, after sitting all night, the first time I turned on the ignition the pressure gauge climbed up to about 15 PSI and started to bleed down. So it doesn't seem to be doing it today.

Now I am wondering if this is a problem that is more prone to occur after the vehicle has been running compared to sitting a long time. Speculative.

Repeated the key on process and saw the pressure go up much further.

It was very clear that with each key-on pressure would rise for a short bit and then start to bleed off which would be consistent with the couple seconds the pump should run.

After the third time I let pressure bleed down to 5 PSI then, without cycling the key to off, just advanced the key to the crank position. The pressure started climbing immediately while the engine cranked and it started after a second or so (pressure was up at 40 PSI by that time). The crank delay seemed to be consistent with your statement about delay after crankshaft sensor pulses and did differ from the times when I cranked with pressure low and it cranked more than a couple second before pressure started coming up and the engine caught with the pressure quite a bit lower.

While idling the pressure did in fact stay stable. It may have moved a PSI up or down, but it wasn't much. And yes the bleed down time, I may have been conservative when I said a minute. Looking at it today it seemed to be well under a minute. Probably closer to 15 seconds to get from 65 PSI down to 10 PSI.

I agree the pre-lube statement seems odd, but it could be a valid reason. It may just be a simple way of doing it verses look at some sensor. It also may have come about cause of some oddities that occurred when they applied fuel and spark earlier.

As someone who designs digital control systems and control coding, if I were doing it I would want to make sure I was getting all proper sensor signals, do at least a full cam cycle (two cranks) before tossing fuel and spark into the mix. So that delay makes sense.

Anyways I'll check those other things. Do that wide open throttle test.

I can't comment on the rest of the behavior. I have done almost no work on this 4.6L so don't know it nearly as well as I do the 2.9L