Help with mystery starting issue!

[BeeGeeSHO]

For the mostpart my 97 SHO runs like a charm with the random exception of it not wanting to fire up VERY occasionally. Around June of this year I went to start the car for the morning commute & to my surprise I couldn't get it to start no matter what. The starter is doing it's thing and has juice. It's almost like the engine wasn't getting that little bit of fuel that it needed to fire up. (temp outside was around 60 degrees)

So I got a ride to work that day and when I got home decided to try it again. To my surprise she started up just as normal right away? Now this happened a 2nd & 3rd time all with about 5-7 days span between each occasion. (2nd & 3rd times temp was also around 60) Again the car would start later in the day (when it was warmer outside?)

Thinking it was a fuel delivery issue, I replaced the fuel filter & listened very closely to the fuel pump to hear if it was engaging or not. All seemed to sound good. (not exactly sure what sounds may indicate a bad pump?) On all occasions when the car wouldn't start, I'd try to turn the key several times to build up fuel pressure before actually starting the car, but still no luck.

I replaced the fuel filter near the end of June & the car has run completely fine up until yesterday. The weather here in Colorado has been hot hot hot between the end of June up until yesterday (Aug 14th) where temps have dipped into the low 50's. So once again I went to start my car yesterday morning & the problem is back (outside temp at 10:30am 56 degrees) Near the end of the afternoon the clouds broke up and temps rose to 60-65 degrees, so after 2hrs or so of warmer temps I tried to start the car and she started fine.

I keep getting recommendations pointing towards fuel symptoms, but as I've obviously alluded to I suspect something temperature related. I've recently relocated to Colorado, so maybe elevation has a role too? I'm not too car savvy so the only thing I can suspect is a flaky sensor someplace?

If everyone else is as stumped as I am, do you recommend a diagnostic test? Even if my car is running fine that day, which may result in the problem not showing up?

Sorry about the novel guys.

1997 SHO
94,*** miles
K&N Cone
Flowmasters
SOON!!! X-Cal (with high altitude programming)

 

[NiNeTy Fo SHO]

First thing I would do is to check your codes. Just b/c the light doesnt/hasnt come on, doesnt mean there isnt anything stored in the computer. Its free...and a good place to start.

Have you tried pushing the gas pedal when it doesnt start to see if that does something?

 

[Wess]

Check your crankshaft postion sensor (CPS). It can cause these kind of problems, leading you to beleive its fuel related, causing you to spend time barking up the wrong tree. If you can get it to Autozone, have them scan it for error codes to be sure. This type of problem won't necessarily cause a CEL.

 

[SHOZ123]

I agree about the crank sensor. It is very easy to change. Sometimes the wire to it gets chafed by the belt where it goes down under the A/C compressor.

 

[BeeGeeSHO]

I have tried pressing the gas pedal as a last resort, still luck in that department.

Can anybody enlighten me about the Crankshaft Postition Sensor (CPS)? What might I be looking for? Where? Etc..

By the way Mucho Gracias y'all.

 

[Mr. SHO]

The Crank pos sensor is easily visible if you remove the front passenger side wheel and pull out the front inner fender on that side. You'll plainly see wires leading to a connector on the engine right next to the crank pulley. Check the wires and you might as well replace the sensor while you are in there. It's a really cheap part and it's actually stocked at almost all parts stores.

 

[BeeGeeSHO]

I'm going to replace the crankshaft position sensor (CPS) ASAP, but was just curious if ambient temperature has anything to do with the CPS & if anyone thinks that temperature may have anything to do with the problems I've (tried) to describe?

 

[Wess]

My advice to you is to get a code reader hooked up to before you start replacing sensors. I wished I did this a couple of years ago when my 95' Probe GT had a similar problem. Poking around the Probe forums I decided to start first with a fuel filter, thinking it was a delivery issue - $10. Next it was the ignition relay, $0, but many trips to junkyards in search of them. Then I decided the distributor must be bad - $380. Each time the problem came back. Finally I had the bright idea of pulling codes and immediately got an error code related to the CPS. Went to my favorite Ford parts counter and got a new one - $50. Problem solved.

Had I done this from the get go, I would have saved a lot of time and $$$. I'm not saying it's not the CPS, because it certainly sounds like it, but you're best to start with reading your codes first. My $.02

Sorry for the book

 

[BeeGeeSHO]

Thanks Wess, advice is always appreciated

 

[Red Devil]

Pull codes, if none, borrow a fuel pressure guage and have at it. It sounds to me more like temp variations are bringing this about, like maybe some condensation issues perhaps?

 

[SHOZ123]

I'd replace it. Like it was said they are cheap and easy to do. You will seldom see a code for a CPS. I would again suggest you check the wring. If it has been messed with then it may easily get too close to the accessory belt under the A/C compressor.

 

[SHOWHAT9]

EVERYTHING YOU WANTED TO KNOW ABOUT CPS
There is all the info on V8SHO.COM regarding CPS. Including pictures.

 

[djbartu]

I've had a similar prob - no codes. When it happened, I would just leave the car alone for a few minutes, go back and it would always start tight up again. Strange! I never did figure it out .... yet.