Going thru the book of knowledge. Hopefully (because scanner won't connect to anything) my phone camera will make these readable. If not I'm sorry about potato cam

 

Please tell me if you need more information as I have most of the rest of the set, especially for the 99 cars. Now if the puppy will stop trying to absorb the book.

 

I won't have any time this evening to do much, but will look hopefully tomorrow when I do have a little time.

I did however manage to test the correct wire from PCM during normal operation and when its acting up. During normal operation I get 12v power for the 2 seconds before startup, and 14v running. When its acting up I get no power at the PCM connection. That was at 4am this morning before work in 25 degrees and ice.

Now I get to figure out why its not signaling as it should.

 

It's starting to sound more and more like something wrong inside the pcm. Maybe a solder point gone bad or something. If it's not showing up at the pcm that's gotta be it. I don't remember if pcms going bad was common. But the sucky thing here is you will need a 99 m/y pcm because of the secondary air injection unless it's a very early 99. Otherwise it will throw the service wrench. Single cam right? Hopefully someone will tell me I'm wrong , but when I needed to swap out the auto pcm for a manual one I found one I needed on eBay for under $100. Quick way to tell if yours has air injection is you'll find a little pump behind the pass headlamp, with a tube running to a check valve ontop of the a/c comp, and from there a tube to the header. You'll have the coffee can pee-cat too

 

I think we may be complicating this a bit too much.

If he fuel pump relay "trigger" coil INTERMITTENTLY grounds itself (shorts), it will lead to no voltage at the PCM when measured relative to ground because there is no resistance across which to develop a potential (V) irrespective of what the PCM wants that output voltage to be at that pin of the PCM.

If he fuel pump relay "trigger" coil INTERMITTENTLY goes open circuit, you would still see 12V at the PCM relative to ground, as the PCM is ready to supply current at this voltage, but when the coil opens up, that current path disappears, but that does not affect the potential V at the PCM.

So, after reading and re reading the posts in this thread, if you re 110% positive there is NO issue with the IP BATT feed on either end, then I will propose the theory that the coil inside the fuel pump relay is intermittently grounding out, thus opening the relay and killing the fuel pump.

 

I went out to try starting it after work and the fuel pump kicks on, but something else is keeping it from firing up. I get voltage at the ignition module pink wire, but I'm not sure if something else is complicating things. This weekend I'll have more time to devote to checking the IP BATT feed, looking over diagrams, and dig some, as right now I just don't have any daylight time to do anything but see if it starts.

 

Do you own a fuel pressure gauge? Hook one up at the rail and see what if any fuel pressure you are getting.

Also, pull the boots off the coils and see if you get an arc across each one. Test best done at night.

 

Since my last post I think I've narrowed it down to either the PCM, or wiring close by. A few times now when its acted up I've been able to point a hair dryer directly at the PCM for a few minutes on high and it activated the fuel pump correctly.

I had finally gotten the chance to test if it was getting fire during this problem, and when its acting up it isn't firing either. I was getting 12v to the ignition modules, but it wasn't sending signal to fire.

As far as testing fuel pressure, when the pump wasn't kicking on, I could test at the valve and there was no pressure. I know it wasn't a matter of the flow of the pump, it just wasn't getting juice.

A few weeks ago I had to change the crank sensor because during testing the fuel pump started working as it was supposed to, but I still wasn't getting fire, and at some point the crank sensor had gone bad as well. I tested it for resistance and it showed as open.

 

Sorry it took so long for a reply, we've been wrangled here with work and kid stuff lately and I've had to leave the car sit for a few weeks. For a couple days over new years weekend it started every single time I needed it to, but then monday morning when trying to leave for work it was crazy again. Thats when I finally took the hair dryer to the PCM and warmed it up.

 

What is the security system doing while all this is going on?

A bad CKP will kill spark and and fuel injectors. Not sure about fuel pump; would be redundant.