Quit---no start for a while then start but quit again, and again---

[millsroger]

My sig truck has been running great--til Saturday morning. Fired up fine, about the time the temp gauge came off the bottom it quit cold. No restart. Sat for about 10 minutes and started right up--repeat every 10 minutes or so.

I thought OH-OH, PMD. Got it home did some quick checks. NO error codes. When no start I had no signal on PMD pin A from the computer, did when it ran. Also no sig to fuel solenoid when no start but ok when it ran.

Hummmm!

I saw a post on no start trouble with optical sensor and a comment about just pulling the plug on it to force limp mode.

Then I saw a discussion and quote from Car Quest saying that the computer will operate in limp mode if either the optical or hall effect crank sensor are disconnected or open, but if either one is "flakey" the computer sees that and shuts down the IP---and does NOT throw a code.

Next time it quit I pulled the optical sensor plug--still no start.

Went thru the quit cycle again and pulled the crank sensor, started right back up.

Got a new crank sensor this AM--runs fine.

Turned out that its not always a PMD that can cause shut down but I learned a quick check using the computer limp mode to trouble shoot with.

 

[matuva]

I would have thought your rig was starving fuel, like with a shot lift pump, or a clogged fuel line or in tank sock filter...

So you had a CPS issue with no code? Good to know

 

[millsroger]

Lift pump runs with glow plugs and I could hear it. When it re-started it ran perfectly until it just died like the key was turned off. It did throw a code 19 when CPS was unplugged but not earlier. Optical threw a code 54 when disconnected. I don't know what the ECM actually looks at to throw the codes but apparrently an erratic or noisy signal isn't always enough.