I have a 2002 dodge ram quad cab. 4.7 engine. 150,000 miles. I just replaced crankshaft sensor and truck still won't start. It cranks but won't turn over. The code still read p1391. Any ideas

 

Welcome to DF.

For future reference:
https://dodgeforum.com/forum/dodge-r...ead-first.html

Will move you to the correct section now.

 

What mods do you have on the truck... is there any chance you have the ASP underdrive pulley installed on it?

In some trucks the woodruff key has been known to brake which would cause the crank timing sprocket to lose timing and a disagreement between the cam sensor and the crank sensor... The ASP pulley has been know to be the biggest cause of the issue although it has happened on engines that have not had the pulley installed.

In a nut shell the crank timing sprocket is only held in place with a VERY thin tab extending from the woodruff key and Pressure from the torquing of the harmonic balancer...

If you cant find your issue... I would start looking there... this is not a small job and you may need to remove the entire timing cover to see... You could try just removing the harmonic damper and see if the Sprocket key way is lined up with the woodruff key.

And it could also be a dirty plug or broken wire going to the sensors...

Also you may want to change the Cam sensor as well... The PCM could be mistaken one bad for the other.

Keep us posted.

SPEED SAFE, AIR RAM

 

Your description is a little vague to say the least. If you want any kind of serious help, you need to provide the backstory. Was the truck running before you replaced the sensor? What brought you to the conclusion that it was bad? You know, tell us what got you to this point, because there is no point in us throwing guesses at you.

 

The truck quit running 100 feet from the house it drifted in the driveway. I went auto parts store and grabbed the code reader. It read p1391 cnf. It wouldn't crank at all I granted the sensor. Now it will crank. But won't start.

 

Agreed.... Help us help you...

I tried corresponding but without information or answers to questions, there can be no real help. So on that note, this is where I would begin with the information I have:

1. Inspect Camshaft & Crankshaft plugs for Oil and or bad pins/wires.... <--- Possible
2. Replace BOTH the Cam sensor & Crank Sensor <--- Possible
3. Check Camshaft Timing Sprocket and insure the cam pin has not sheared from the cam. This is found by removing the passengers side valve cover and removing the cam sprocket. You will need to install a Cam Wedge tool and zip tie the chain to the cam sprocket before removing the sprocket. Remove sprocket and make sure the timing pin is still visably protruding from the cam surface... This should line up with the hole on the cam sprocket. <--- Possible
4. Check Crankshaft Timing Sprocket & Crankshaft Woodruff key... This key has been known to brake and cause the crank sprocket to lose timing.<--- Possible

Good luck... Keep us posted.


NICK