Cranks no start

Hello and thank you for your quick response. I should expound on what has happened on the car the last couple years. Had it serviced around 100,000 (4 years ago) and I ended up having to fix several things that weren't completed myself. Replaced crank sensor when the car started acting flaky about 3 years ago and it ran fine afterwards (used a Wells Mfg. Sensor). This Spring I tried to start it and it just cranked. Put it on the charger overnight, still cranked but no start, so I started pulling fuses and resetting modules that had to do with engine management, boom, it started right up. That is when I noticed the oil leak so I did not start the car more than a few times over the Summer. About a month ago I decided to replace the valve cover gasket. The car fired up on the 1st touch of the key, I backed it up towards the garage and replaced the gasket, put all the connectors back together and tried to start it up. Seems like its getting fuel as I said. The main problem for me is I don't bend like I used to and as you know this is a bear to work on. I was hoping someone made a breakout box for the PCM so I could easily test the sensors, maybe you know? I do have the service info and schematic which helps a lot. I will read the info you attached and get back to you Ken, much appreciated! Looked at the schematic and noticed a capacitor on pin1 of the distributor (2 way conn.), Is that correct and if so, where is it? Thanks

Hi Ken, I tested for spark after I pulled battery negative and checked resistances to most of the sensors for obvious shorts or open circuits (via the lifted PCM connectors), only the pin 6 line from the PCM connector to the ASD relay was questionable at 2.5 ohms (this also goes to the Generator, Distributor, and to fuse 1 of the PDC. Then I set up to test spark on the no. 6 plug, Wife assist mode with instructions "shut down immediately if engine starts". Of course it did, so I put it all back together and wonder what the next step should be. Seems to be triggered when the car sits for more than a couple days but doesn't seem to be a battery issue as I put a full charge on the battery overnight before attempting to start it, also pulled B+, none of which worked. Has anyone published a list of resistance values for the sensors on this car? I know when the Hall effect crank sensor went bad, I was able to rig up a circuit with my scope, B+ and ground, sensor output, a piece of ferrous metal, and passed it back and forth past the metal and could see the output on the scope. Thanks

Yes, that's about it, sitting seems to trigger it, though can't definitely say that's it. The scope is an old 50 mhz Hewlett Packard dual trace from the 1960's I bought that was military surplus. I'd probably want to use an isolation transformer with it if I use it on the car. It is beginning to remind me of a problem I had with my 96 Express van for years. Every time it rained or got damp, the van would crank but not start (350 V8). Of course it was often the plastic distributor with inadequate venting that loaded up with ozone and fouled the contacts. This year though, the contacts did not look bad, so upon the advice of a friend, I checked the resistance of the ECT sensor. I think it was 50K ohms, which I believe equates to a temperature of 50 below zero on the chart I saw. So the ECM was telling the injectors to pump like crazy. Of course I never smelled gas, Its run perfect since replacement, Thanks, Greg

Hi Ken, the car is taking fits again after sitting. Again crank and crank, no start, but, it did something strange this time. Unless my eyes failed me, I could have sworn I saw a puff of smoke right at the beginning of cranking, looking through a dusty windshield it was hard to tell what type. Kept charging then cranking and after about 4 or 5 rounds of that it fired and ran perfectly. Could this be an intermittent head gasket issue? Was the 2.5 V6 known to have odd head gasket issues? Thanks

Hi Ken, well it has been awhile. Car was still smoking after the front valve cover was replaced. So I took it in and the rear cover was replaced. Also had the muffler replaced, they checked it out, it ran perfect again. Until it sat for 3 or 4 days (after I took it home). Then it took another fit, had to crank and crank, finally fired and started but acted like it was missing, and, upon cracking the throttle open quickly, bucked like crazy and almost stalled. Shut it off after that, restarted, perfect again. Have went out every 2 or 3 days, started and run perfect. No codes except for ongoing ABS light which I believe is a tone ring. I'm beginning to think fuel pressure or an intermittent sensor, as I mentioned before similar to what happened with the CTS on my van. Thanks

Hello again Ken. Well, I have 2 failure modes, 20 percent of the time it won't start, seems like sitting might bring this on, not sure, other failure mode is it starts and idles fine but as the engine warms up and transitions from open to closed loop it starts missing at idle (not sure about off idle). This seems to be happening more frequently. Any ideas are appreciated.

Thanks,

Greg

Kase, I finally took off the throttle body, cleaned it out completely, replaced the IAC motor, reassembled, have been driving without incident for about 3 days now. Hopefully that's it.

Thanks,

Greg