Bad Rail Pressure Sensor?

Dtruck1

Dtruck1

Engineer
Joined
Jun 22, 2010
Messages
434
This has been happening on and off for the last month.

First Instance: Was close to the house, came to a stop sign and put the trans in neutral. (G56) Rpm went down to 400 and slowly recovered to normal idle rpm. Still idled smooth. Shut the truck off at the house. Went out a few hours later and the engine started, but only went up to 400-500 rpm then slowly died. Accelerator input had no influence on the engine continuing to run.

Unplugged FCA and engine started. Shut off engine and ordered a new FCA.

Installed new FCA, truck started and ran fine, for a week. Now it is doing the same thing again, but it seems to come and go. Sometimes I can go a few days and no problem, then out of the blue, I come to a stop, before stopping place in neutral, and then rpm goes down in the 400 range, and then the truck barely wants to start.

Any ideas? I was thinking intermittent rail pressure sensor.

Thanks,
Rob
 
Any codes? When mine went bad it had a really bad lope/knock and was billowing out black smoke. All 3 pins were corroded on the sensor.
 
Are the RPM really that low, or is that just what your tach is reading? Mine reads wrong most of the time, it is a known issue, FYI.

If they really are that low I highly doubt it is the RP sensor, but if you want to try a known good one, I have two spares, I could let you try one, if it fixes the issue I will sell it to you for $100 shipped. Let me know.
 
Thanks for the input guys. I found the problem. I was messing around with the wiring harness at the rail pressure sensor and when I wiggled it around the plug, the engine kind of stuttered for just a split second. I then shut the engine off and restarted. Started normal. Pulled the plug on the sensor and found corroded terminals. Cleaned them up and haven't had any issue today.

There were no codes being thrown when it was acting up.

Verified RPM with a reflective tach and a piece of reflective tape on the balancer.

My guess is I was getting low volts at the sensor, but not out of range, just enough to jack with the low rpm rp.

Thanks again,
Rob
 
Thanks, I hate intermittent electronic problems. This time I got lucky. Thanks again.
 
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