Weird starting problem

[aldive]

Yesterday was the first time my ’99 SOHC failed to start ( ever ) on the first turn of the key.

It cranked but failed to start. Upon repeat attempt to start, it just cranked but did not start.

At this point, I elected to change the computer tune from my gas mileage tune to the stock tune ( via XCal2 ). Then when cranking the truck, the same results as before.

After letting the motor crank for a long time, the truck started and ran perfectly. The truck continued to start normally until this afternoon when the above scenario repeated its ugly self; however, during the cranking it, at one time, made a sound like an old carbolated motor would do in a backfire situation. And the motor would shake.

After continually cranking the truck finally started and ran perfectly. The idle was perfect and smooth. A road test showed normal even under hard acceleration.

At no time was a CEL illuminated. After hooking up my scanner, all functions appeared normal.

The next step was to check fuel pressure. With key on and not cranking the fuel pressure was 45 psig and while running was 65 psig. After turning off the motor, the fuel pressure leaked down only 4 psig after 30 minutes.

The situation has me perplexed. I need this truck to crank every time.

Any comments or suggestions welcomed.

Thanks ….

 

[JohnJ]

The fuel pressure leaking down would certainly explain the hard start so you've got to find out why it leaks down. Only three things will cause a fuel pressure leakdown (excluding the scary external leak). Pump, regulator, and injector.

An injector is always going to be your first suspect, so you want to pop the fuel rail with injectors out and see if any of them drip (after cycling the key on/key off). If that sounds too smelly or you don't want to deal with the o-rings possibly becoming damaged you could also try waiting for the pressure to leak down, then starting and immediately stopping the engine, then looking for a single slightly carbon-fouled spark plug.

 

[A Wise Guy]

Something else that has affected me in the past was my PatsII system. If while you are cranking the 'THEFT' light is blinking rapidly the computer is not picking up your chip properly and not allowing the truck to start. Hope this helps rule in or rule out a problem. Good luck.

 

[aldive]

bump

 

[aldive]

Just went out to start the truck and all I get now is cranking - no start.

I tried different keys with the same results.

Any ideas guys?

 

[Cobraguy]

The fuel pressure leaking down would certainly explain the hard start so you've got to find out why it leaks down. Only three things will cause a fuel pressure leakdown (excluding the scary external leak). Pump, regulator, and injector.

An injector is always going to be your first suspect, so you want to pop the fuel rail with injectors out and see if any of them drip (after cycling the key on/key off). If that sounds too smelly or you don't want to deal with the o-rings possibly becoming damaged you could also try waiting for the pressure to leak down, then starting and immediately stopping the engine, then looking for a single slightly carbon-fouled spark plug.

I think you misunderstood him. The fuel pressure only fell off 4 psi after half an hour. That's the way I read it. And that is phenomenal. But even if it fell off to zero in 5 minutes, that wouldn't be his problem. He's cranking it enough to build pressure again. I would say it's time for some diagnostic work with the proper scan tools. I'm wondering if it's lost a cam sensor or something like that.

 

[aldive]

I think you misunderstood him. The fuel pressure only fell off 4 psi after half an hour. That's the way I read it..

Correct.

 

[aldive]

Spent the day diagnosing the no start problem with no positive results.

All features on the truck ( except start ) work perfectly.
No KOEO codes or pending codes present.
Fuel pressure is fine.
Spark is present.

The computer tune ( I have tried several ) makes no difference.

The PATS works perfectly.

The truck performed perfectly on the 1200 mile road trip last weekend. I even got excellent mileage.

I am completely stumped.

Come of guys, give me some ideas and suggestions.

 

[Hitchhikingmike]

I have had this exact same problem on my xls '02. The only difference is that my truck is newer and only has 40k miles. I have this problem about once every two weeks, sometimes just once a month. Last winter when it got colder (here in texas), the problem occurred more frequently, but went away now that summer is just about here. Never the less it does come back every two weeks about.

When I have this problem the engine always cranks, but never starts. However it has always started on the second or third try. Sometimes it does start on the first try, but it is just a delayed start after it had to crank a few seconds.

Goodyear checked the spark plugs and pressure of the fuel pump, amongst other things and could not find anything wrong. I have a feeling that the culprit is the fuel pump. I'll be damned if I have to replace my fuel pump at 40k. My fuel pump does supply adequate pressure. I'm just think that the pump seizes when the explorer is off and siting and it just takes a few seconds for it to unjam and start turning.

I picked up a fuel filter at pepboys the other day and will be replacing that soon the next few days. The fuel filter has never been changed so I'm hoping I might be able to nip the problem right here in the butt.

What do you think my problem is? Think it is related to yours? BTW my ex is all stock.

 

[Turdle]

Al
If it was me i would suspect the fuel pump was going south. I would replace it while at home-
Try using the pump itself to empty the tank-by disconnecting the fuel filter and placing the fuel line in a large gas can. The flow is only 90 lph max-which shouldn't be too bad.

 

[aldive]

Al
If it was me i would suspect the fuel pump was going south.

Jon, I too would lean toward the fuel pump except the the fuel pressure immediately goes to 45-65 psig with the kurn of the key.

With that much pressure, and little to no leakedown, one would expect the truck to at least fire.

Keep the ideas comming,; I truly appreciate them.

 

[Turdle]

I'm sorry,
I read it like this-
the truck didn't start-but then it did. next step was to check pressure-

I assume you checked the pressure while it was in no start condition?

 

[aldive]

I'm sorry,
I read it like this-
the truck didn't start-but then it did. next step was to check pressure-

I assume you checked the pressure while it was in no start condition?

Indeed, I checked the fuel pressure when it last started ( 65 psig ) as well as now that it won't run.

 

[Turdle]

Ah
Next step would be the Crank position sensor. Check that the trigger wheel is indeed turning and on time-(there was a recent broken key on the board)

You Have a timing light I assume-I would double check this


Then-you might check the Oil pressure sensor ( does the oil pressure come right up while cranking?)

also-check the ECT ( ecngine coolant temp ) sensor.

 

[JohnJ]

I think you misunderstood him. The fuel pressure only fell off 4 psi after half an hour. That's the way I read it. And that is phenomenal. But even if it fell off to zero in 5 minutes, that wouldn't be his problem. He's cranking it enough to build pressure again. I would say it's time for some diagnostic work with the proper scan tools. I'm wondering if it's lost a cam sensor or something like that.

See this is what happens when I try to read while my dog is stomping on my face. Anyway...

I'm making the assumption that you tried tapping the gas in case the IAC is going and you tried WOT cranking and you've tested for spark at all 6 because you seem to be the sort of guy who'd check all the basic stuff right off the bat.

Here's one people sometimes forget about: could you be suffering from an EGR valve hanging slightly open? Sometimes an EGR valve gets enough carbon built up that it doesn't seal closed which can make for som very difficult starting. It isn't a particularly common condition on Explorers but with all your highway miles it might be worth a quick look.

 

[aldive]

Next step would be the Crank position sensor. Check that the trigger wheel is indeed turning and on time-(there was a recent broken key on the board)

Appeared to be fine.

Then-you might check the Oil pressure sensor ( does the oil pressure come right up while cranking?)

All is well here.

also-check the ECT ( ecngine coolant temp ) sensor.

The temperature as reported by OBDII is fine.

Jon, keep the thoughts comming.

 

[aldive]

Here's one people sometimes forget about: could you be suffering from an EGR valve hanging slightly open? Sometimes an EGR valve gets enough carbon built up that it doesn't seal closed which can make for som very difficult starting. It isn't a particularly common condition on Explorers but with all your highway miles it might be worth a quick look.

The EGR is relatively new and is/was functioning perfectly.

 

[Hitchhikingmike]

Al, like my explorer, is this just an intermediate problem that happens ever so many starts or can you just plain not start your explorer at all? Thanks. Just wondering. Thanks.

 

[aldive]

Its completely dead.

 

[aldive]

bump