Intermittent Starting problem, No spark-No fuel

[JPA]

Hey gang,
98, 4.0 SOHC, 120k, auto, 2wd, air, Motor Vin (E) blah blah blah

I need help with this problem. I have replace the CPS, the fuel pump has been replace a few months ago. The fuel pressure is within spec. This problem has been going on for about a month now. When the (one I must obey) wife tried to start the exp. it would not start. After a few tries it started. The problem got worse as time went on. Last week, my wife tried to start engine the darn thing, would not start. At this time I had not replaced anything, I was in just diagnosing the problem. As I was testing for spark the engine fired up. The car started every time I tried. Things that make you go hummmmm.
The next morning, my wife starts the car dirves to our place of business, parks the car, gets ready to leave for the day... *&#%$ thing will not start. This was Friday night. Staurday morning, I drive to our business try to start the engine, it fires-up as if there was no problem. Drive it home, at this point I thought that the CPS (cam position Sensor) may be bad. I did a spark test again - no spark. I install a new CPS, the engine fires up no problems. Wife and I use the car all day Sunday -No problem ran fine all day. Monday, wife goes to start the car, will not start. Last night I spent the better part of the night trying to figure out WTF is going on. If anyone has any ideas of what to try next, I am open for suggestions. I have most of the necessary test equipment. Gauges, meters and know how.
Thanks for taking the time to read this post. This making me crazy. I'm now leaning toward the PCM.
JPA

 

[MrShorty]

I would suggest posting this (or a moderator moving) to the EEC-V forum or the Under the Hood forum, where someone more familiar with a '98 will be more likely to respond.

My first thought when you lose both fuel and spark is a problem with the main PCM power supply and/or ground. The intermittant nature of your problem sure seems like a loose connection somewhere. Can't help beyond that, because I'm not familiar with the '98 engine controls.

 

[JPA]

MrShorty, thanks for your reply. Let me ask you this, if the PCM does not see a signal that spark can be made, does the PCM shut-off the fuel pump? I hear the fuel pump prime the system. I have gauge tested and manually tested to see if fuel was present during priming. Hold in the schardar valve during prime fuel shoots out. Hold valve in during crank, no fuel. This leads me to belieive that if the PCM does not see all the correct input signals from spark related components. The PCM will drop the FP power. What do you think? or is this a correct assumption. (knowing darn well what happens when one assumes something).

 

[MrShorty]

That is certainly true for an EEC-IV equipped vehicle. For our '92's, for example, the PCM waits for the PIP signal which is generated by the ICM in response to the crankshaft position (CKP) signal. If there were a problem with the ICM or the CKP circuits, then you could get very similar symptoms. You would also likely get a PIP circuit fault (or similar) memory code. Fast forward six years and see how your '98 gets the same effect.

 

[msd]

jpa how did you fix it my ranger is doing the same thing f*** it in the a** i cant fined out what rong with it i but in a new ckp still no start HOW did you fix it enithing helps +)