Hi all, driving my 2004 started to run like **** then quit , won't restart , checked fuel pressure looks good 7 psi , new filter , etc , put the scan tool on it , rail pressure when cranking varies from 2000 to 4000 ? so is my cp3 bad ? will the truck still run if only the rail pressure sensor is bad ? or does that shut it down as well ? thanks for the help !!
My truck only has about 80,000 miles on it ,

 

I'd look at the rail pressure sensor, then the rail pressure relief valve.

It could also be a bad injectors.

 

is there a specific way to check those 2 items ? thanks

 

Rail pressure valve is a replacement, injectors can be tested, but are pricey.

There may be a way to check the RPV, but I don't know off the top of my head.

 

I have been looking around the forum , is there any pic of rail sensor and the prv ?

 

 

thanks everyone here is a great help ,

 

here's a question , if the rail sensor pressure switch fails ? will the truck not run ?

 

The ECM looks for a certain rail pressure before it will let the truck start. If the RPS is bad, then the truck will not start. Some people whave used either to start their trucks when this happens, I do not recommend it due to damage to the head, cylinder walls and pistons. I don't have first hand knowledge with this, plenty of people do it, but I'm not going to chance a 12k longblock replacement with a squirt of either.

If you do use either, disconnect the grid heaters.

I believe that a starscan tool that dodge has will read the cranking rail pressure and test the RPS.

They are not that expensive, from what I understand. Decide what is cheaper, an hour or two of labor at the dodge joint, or a rail pressure sensor.

 

Have you done the key trick to check for codes. ?
I believe genos garage had the rail assembly with PRV and sensor for a third of what dealer wants.

 

If the relief valve has blown it won't let the rail build any pressure.....no start!! Pull the banjo bolt off the top of the relief valve.....if fuel is present there that could be your problem!!! Not a definite solution but a place to start.

 

Ok , scanner reads pressure switch all over the place , I removed the return pressure line there is some fuel there ? so I removed the prv and pluged it at the manifold , and the rail sensor is all over the place in psi ? so where is a good place to get a rail pressure switch

 

Sounds like the FCA is giving false readings......much like mine did.

 

what is the fca ? sorry to sound dumb ?

 

Ok , so the shop said the pc3 was bad , they replaced it , guess what no start , psi reading on scanner is all over the place 2000- 4000 , so replaced the fue pressure sensor ? same thing ? no fuel going passed the prv, unplug the fuel pressure sensor , reading goes to 18,0000 psi , plug it back in reads 0, crank the truck it's all over in psi ? and no start , everything on the scanner looks good tps , etc