2005 Deville cranks but no start

[Old Timer]

My wife stopped at the grocery store and when she came back out, the engine turns over but no start. I checked the fuel pressure and it was about 41 psi. I checked for trouble codes and none found. The car has been running fine until now. She did not put gas in recently and has about a half a tank. It has 255,000 miles on it. I checked for spark and it looks good. Next would be to check for power to the injectors with a small led.

Edited November 16, 2019 by Old Timer

[Old Timer]

Update: I have no injector pulse.

[OldCadTech]

I think the minimum fuel pressure is 45psi, but I could be wrong.

Fist thing that comes to mind is the fuel pressure regulator. Since your update, no injector pulse, I'm leaning towards a cam or crank position sensor.

Check for codes with a scan tool. The PCM may not be seeing the engine cranking

 

[Old Timer]

Fuel PSI is between 41-45 running. I spent hours with torque pro on my phone and Scan XL on my laptop with no results at all. RPM at cranking stayed around 150, which from everything I have read was normal. Having an RPM reading kind of ruled out a bad crank sensor or 2, since this engine has 2. In desperation I pulled the PCM out and pulled the connectors off. Cleaned the connectors with CRC electrical cleaner and tapped on the PCM. Reinstalled the PCM and the car cranked right up. I'm not sure if this would be a fix, but it's running fine again now. Hope this might help somebody in the future.

[OldCadTech]

Okay, it's great that you have it running again but the tap test on the PCM is a test for a defective PCM.

Unless you cleaned a bunch of corrosion from the contacts I would replace the PCM.

[Old Timer]

The PCM is worth more than the car! I agree that it should be replaced, but the wife wants to just drive it. I'm not going to try and argue with her.  

[OldCadTech]

LOL, I agree, the wife may NOT be too happy if it happens again ( only a guess )

 

[rockfangd]

Correct me if I am wrong but I thought the RPM came from a cam signal. 

It is late and monday so I apologize if I am incorrect.

If problem does reoccur and ends up being related to the PCM maybe you could possibly find a good donor to program

[Old Timer]

I never could get clear information about where the tach signal comes from. It could be the cam sensor. It was a lot easier to diagnose problems when I worked in the Cadillac dealership. They have any information available you could ever need, but they don't want to give any of that out. The service manager that I worked with even treats me like a stranger. I knew the guy for about 20 years. The GM training centers were great and gave a bunch a literature when I was sent for classes, but that was a long time ago. I worked in the dealership when the nightmare 8-6-4 came out, but mostly I worked on the diesels. I was in it for a lot of the evolution up to the Northstar, and then opened my own shop. This 2005 came from the factory painted dark blue, but it should have been lemon yellow cause it has had problems one right after another.