97 Explorer cranks but won't start

[Wordwoman]

My 97 Explorer has once again been towed home. It sits in my driveway, cranks but will not start. Sort of like "Groundhog Day", I have been reliving this same scenario every three to four months for the past three years. What happens is that the car is fine one minute, then suddenly refuses to start. Fortunately this situation often happens in my own driveway. You wait a day or two and blammo-----it starts right up and hums for another couple of months. On at least seven occasions I have had it towed to repair shops or Ford dealers, only to be told that since the car started right up for them, they could not recreate the problem. Last time I even went to the dealership to try to start it both weekend days to make sure it was still being stubborn. And of course-----come Monday morning, it starts just fine for them and I am out a couple of hundred dollars for diagnostics which reveal nothing.

I have replaced the IAC FOUR times. New fuel pump and filters. New DPFE.
New plugs and plug wires. New air filter. New starter. New vacuum hoses.
And still for some reason my Explorer becomes a stubborn mule and needs a vacation. A mysterious mule which cannot be diagnosed for some reason. For the first time my current breakdown occurred while driving instead of being parked. Just suddenly stopped. Fuel pump is working. Fuel is getting to the engine. There is spark.

I have read thousands of Ford messages and see that many others have a similar problem. Does anyone out there have any idea what the heck could be going on with my Explorer and what I could try to get it started if it doesn't magically wake up in a day or two? Had anyone else had this same experience???? I feel unsafe everywhere I go worrying that I will be stranded. Three different Ford dealerships haven't been able to come up with anything. I love my Explorer, but since this is my first Ford-----is this typical for Fords?

HELP!
Thanks,
Marilyn Robison

[Alec]

The first 2 things to pop into my mind are:

battery cables/connections
computer

[Wordwoman]

Originally Posted by Alec

The first 2 things to pop into my mind are:

battery cables/connections
computer

Took the battery cables off and on several times hoping that resetting the computer might make it wake up. Connection and cables are fine.

[Opera House]

You crank, have fuel, and spark. What else is there? Obviously one of those is not true. I had an intermitant and drove around with a meter in the cab monitoring fuel pump current. Only then could I see the current slowly drop before the engine stalled. That at least told me it was a fuel problem. Weeks more of testing eliminated everything but the regulator. That was only proved by replacement and cutting open the old regulator. It is hard to get a mechanic interested in these kinds of problems because they can't make any money on them. If most of what you said is true, I would suspect a fuel problem. The pump may be running but the fuel pressure is too low because of resistance in the circuit going to it or a regulator problem. All you can do is hope that it gets worse.

[Wordwoman]

Originally Posted by Opera House

You crank, have fuel, and spark. What else is there? Obviously one of those is not true. I had an intermitant and drove around with a meter in the cab monitoring fuel pump current. Only then could I see the current slowly drop before the engine stalled. That at least told me it was a fuel problem. Weeks more of testing eliminated everything but the regulator. That was only proved by replacement and cutting open the old regulator. It is hard to get a mechanic interested in these kinds of problems because they can't make any money on them. If most of what you said is true, I would suspect a fuel problem. The pump may be running but the fuel pressure is too low because of resistance in the circuit going to it or a regulator problem. All you can do is hope that it gets worse.

I am more inclined to suspect an electrical or computer problem. Three years for a regulator to act up and not completely fail seems hard to imagine. Then again, Ford mechanics trained in their product not being able to come up with a solution is equally hard to imagine.

Can you elaborate a little more on the meter you used to monitor the fuel pump current and how and where you connected it?

[Wordwoman]

Also------since we sprayed starting fluid into the throttle body and it still just cranked, doesn't that eliminate a fuel delivery problem?

[pmcmaster]

When it fails to start have you confirmed that there is fuel at the injection rail test valve?

[Wordwoman]

Originally Posted by pmcmaster

When it fails to start have you confirmed that there is fuel at the injection rail test valve?

Yes, there is definitely fuel at the injection rail test valve.

Out of desperation, tonight I purchased the Crankshaft Position Sensor. The price at Auto Zone was right------$10. Wish me luck tomorrow that this might be the fix to get it started.

[AlaskanJack]

wll that's what it sounds like to me. twice now a woman I work with has called me and asked me for help cause her Ex cranks but wont start. I crawl under it and tap the CPS and vrrrooom. Fires right up!

[performancenut]

I would bet more on PCM, cranshaft position sensor, and/or camshaft position sensor if fuel supply is OK.

[Opera House]

I would guess the crank position sensor too, but they said they had spark. If you wan to do the fuel pump current test it is as follows:

1. Remove maxi fuse #3 (for 97) 30A lt green.
2. Use lamp cord to connect to meter. 1/4 male spade crimp connectors will fit in the fuse socket. Wire the other end to a 10A meter in the cab.
3. Normal current should be around 4-5A. Lower at idle and about 1/4 A higher on hard acceleration. This low vacuum condition can be simulated by removing the vacuum line on the FPR.
4. It is normal for the current to drop about 1/4 amp after the pump has been running about 5 minutes and the windings warm up.
5. Below 2A the engine usually will not run. Please note that the computer shuts off the fuel pump after a few seconds if the engine is not running.

Just what vehicle are we talking about, three years????? A 97 is closer to 7 years old. The FPR in my 92 failed at 5 years. CPS for $10. I thought these were closer to $30.

[Wordwoman]

Drats! Not the CPS. Changed it, and same old same old. And yes-----I was shocked that the CPS was $10, too. First Auto Zone tried to give me one for a 94 Explorer which cost $29.99. When I pointed out they had the year wrong, they brought out the CPS for a 97 and said this one rang out at $9.99.

It's also not the relays because I can hear them click open when I turn the key on. Checked for spark again, and definitely have spark.

Thanks for the suggestion on the fuel pump current test, Opera House. I am off to give it shot right now.

[Wordwoman]

That'll teach me for not putting my glasses on when reading a reply. I can't try the fuel pump current test because the car hasn't started in two days. If it ever magically starts again (two days was the longest it ever went before), I will try the test.

[pmcmaster]

Marilyn,
I know you say say that you have fuel but for what its worth I have had the near identical problem i.e car would run perfect for several days then would refuse to start, leave to following day then it would start perfect as if nothing was wrong. The several days then became every other day then every day but in all these instances no fuel was the problem (when not starting). I eventually tracked the problem to (from 96 onwards) Fords fitted a HF inteference suppressor to the fuel pump power line and it was this breaking down that was causing the intermittant problems.

[Wordwoman]

Originally Posted by pmcmaster

Marilyn,
I know you say say that you have fuel but for what its worth I have had the near identical problem i.e car would run perfect for several days then would refuse to start, leave to following day then it would start perfect as if nothing was wrong. The several days then became every other day then every day but in all these instances no fuel was the problem (when not starting). I eventually tracked the problem to (from 96 onwards) Fords fitted a HF inteference suppressor to the fuel pump power line and it was this breaking down that was causing the intermittant problems.

Elaborate a little on the HF for me------and please excuse my lack of knowledge----- but what does "HF" stand for? Whereabouts is the suppressor located, and do you know if there is any way to test for this?

[Alec]

the fuel pump can interfere with radio communications. the suppressor helps this problem.

[Opera House]

You can still check for pump current in those first three seconds. Another thing to check is the power going to the fuel injectors. This would explain pump and ignition working, but no start. Injectors in a V6 are in two banks of three parallel injectors. Red wire should have 12V anytime the key is on. White and tan are switched to ground for short periods of time. It is unlikely both switching circuits in the PCM would fail at the same time. So, I would concentrate on seeing if the 12V is there. Pins are very handy to make connections to wires. The PCM/ECM relay is something else to suspect. In this later year, A diode is in series to prevent the battery being connected reverse polarity. Only heard of a couple cases of this diode going bad. There are two of them in the fuse distribution box. The other one is for the AC, switch them. They look like a black fuse but one pin is a different direction.

[Wordwoman]

Originally Posted by Opera House

You can still check for pump current in those first three seconds. Another thing to check is the power going to the fuel injectors. This would explain pump and ignition working, but no start. Injectors in a V6 are in two banks of three parallel injectors. Red wire should have 12V anytime the key is on. White and tan are switched to ground for short periods of time. It is unlikely both switching circuits in the PCM would fail at the same time. So, I would concentrate on seeing if the 12V is there. Pins are very handy to make connections to wires. The PCM/ECM relay is something else to suspect. In this later year, A diode is in series to prevent the battery being connected reverse polarity. Only heard of a couple cases of this diode going bad. There are two of them in the fuse distribution box. The other one is for the AC, switch them. They look like a black fuse but one pin is a different direction.

Thanks for taking the time to help me figure this out, Opera Man.

Did the check you suggested, and there is definitely 12V. Also switched those two black relays. Nothing. Still just cranks. At least I know I have a strong battery from four days of cranking.

[Wordwoman]

Excuse me--------I must have Adam Sandler on the brain. I meant, Opera HOUSE!

[pmcmaster]

The HF is High Frequency Radio Interference (think this effects radio coms/transmissions rather than the radio reception on the car radio) the suppressor is fitted to the top of the fuel pump assembly (the round plate thats bolted to top of tank), its a black block, held down by a metal cage which is spot welded to assembly plate i.e. its not replaceable on its own, you have to replace complete assembly (in the UK that includes sender unit & fuel pump - might be diff in US). Power supply to pump passes through suppressor before going to pump, suppressor also has ground which is spliced to fuel pump ground plus 2 other wires which run in the harness to the block connector at the inside of the left side chassis rail (level with back end of tank). If you can see top of tank (dont think you can without dropping) you will see the suppressor on top of plate (sticks up about 2inches) otherwise check wires in above block connector. Without suppressor I think you will have ground(Bk)+power(Pk/Bk) to pump, Ground(Bk/Y) + Return(Y/W) to sender i.e 4 wires. With suppressor you will have 2 extra wires (Red/Green stripe) & (White/Blue stripe). Dont know of any tests/checks (perhaps OperaHouse can help?) other than as it failed it blocked the power supply to the pump. In the early days of failure although diagnosis pointed to the fuel pump I couldnt believe how a pump could work one day and not the next, it was only in the end when it failed completely that I had no option but to drop the tank and replace pump. When I removed pump and was able to test independently direct to the pump terminals and it worked ok I then checked this suppressor thing then it became clear what the problem was. I have no idea how a suppressor works and why it broke down the way it did!