97 4.0 SOHC Intermittent Start

[bzinga]

My 97 Explorer XLT 4.0 SOHC, 83k, has failed to start twice now. We bought her about 2 months ago off an old lady who drove it very little for the past 12 years. I know very little about her past care. It has failed to start after a 2 and a 25 mile drive. Acts like it's not getting fuel. However, smell gas. Giving it alittle gas while trying to start up does nothing. Not the cutoff switch. Cranks but does not start. Or almost starts but chugs and stalls out. Wait about 30 mins both times, starts up like a champ. Bout 2 weeks in between no starts. Inspected the crankshaft position sensor, looks like there has been contact between the sensor and the pulley, drag marks. Best bet? Thanks ahead of time.

 

[drdoom]

Fuel pump fixed mine.

 

[chefduane]

Upper Intake Manifold gaskets. Any codes?

 

[bzinga]

No codes. It doesn't have other typical symptoms of an upper manifold gasket problem, but I'll not negate it just yet. Fuel pump seems to be a common answer in similar threads, sometimes it worked for some, sometimes not. Did you have similar probs drdoom? Only bc we smell gas did we think the pump was working fine.

 

[drdoom]

Yes, very similar. I tested every sensor I could: TPS, CKP, CMP, ECT, coil and spark test as well. All passed. Strong fuel smell all along too. For a while I had to cycle key three times to get a reliable start. You do want to confirm your injectors are firing though, because there is a protocol in the PCM that shuts them down (clearing mode & also no CKP signal??) not entirely sure about this though, more knowledgeable please chime in. CKP sensor or fuel pump are most likely. CKP connector gets road spray and fluid leaks, check that connection... oily in there no good. The sensor itself is Hall Effect so that's easy to test with a multimeter and a piece of steel. Don't think it should be dragging, look closely at the marks are they 360° all the way around or partial?

 

[bzinga]

this picture has the same marks, the two lines going around, that im seeing. cant tell if they are all the way around or not. havent found any info about it, normal or not.

 

[Flash]

A faulty CKP sensor throws a code doesn't it?

 

[drdoom]

I believe so Flash, like the MIL doesn't illuminates at start up? Does that sound right? Not sure if it will set a code without running though.

 

[drdoom]

I don't see any problem in the photo. Looks normal.

 

[bzinga]

Yeah, I would expect it to throw a code too, which it doesn't. And it's running now, started after about 20 mins of lettin it sit, then drove home bout 20 mins away.

 

[2000StreetRod]

wear marks

As I recall a new crankshaft position (CKP) sensor comes with plastic bars to set the spacing correctly upon installation. The bars wear down almost immediately after the engine starts and leave corresponding marks on the harmonic balancer.

Intermittent starts frequently result from faulty fuel pump or faulty crankshaft position sensor. The fuel pump runs continuously when the starter is cranking the engine or the engine is running if the PCM determines the crankshaft is rotating via the CKP sensor. For safety reasons the PCM disables the fuel pump immediately if there is no indication of crankshaft rotation from the CKP sensor.

I suggest you clean the CKP sensor connector by connecting/disconnecting a couple times and then check the fuel pressure: Ford Explorer Ranger Fuel pressure test procedure

 

[bzinga]

Will do, thanks all, will keep the thread updated!

 

[bzinga]

Had a stall out while driving, no restart. Towed home. Restarted in the morn like nothing happened. Did fuel pressure test, idle w/vac bout 29 psi, no vac, 40. Replaced the ckp sensor. Test drive, stall, no restart. Started in the morn. Going to work on the pump next. However during and after the last test drive the steering was shuddering bad at times, small bumps made it feel like there was a lot of play. Result of vacuum portion of fuel test? Any ideas? Thanks.

 

[Flash]

The steering shudder is likely to be air in the power steering hydraulics.

With the engine running cycle the steering from lock to lock a few times to purge any air.

Your fuel pump might have weak brush springs or worn down brushes causing bad contact at times.

 

[bzinga]

Well it's been a few months now, glad to say after replacing the fuel pump, we haven't had those issues again. As for the steering shudder, took it to ford, they did an update to the gem module, and serviced the rear differential, new fluid n whatnot. Been fine since. Thanks for the help yall.

 

[chefduane]

Well it's been a few months now, glad to say after replacing the fuel pump, we haven't had those issues again. As for the steering shudder, took it to ford, they did an update to the gem module, and serviced the rear differential, new fluid n whatnot. Been fine since. Thanks for the help yall.

I read previously that it stalled out and would not start. Yes, that would NOT be a symptom of upper/lower mani gaskets as typically they cause cold start issues but once warm, expand enough fill any voids.

Good to hear a new fuel pump solved the problem. But, I don't understand how a steering shudder would be fixed by a GEM update and servicing the rear diff.
Ford give you any additional information on that? I just would like to understand the issue and resolution.

 

[drdoom]

Chef I thought the same thing...