Ok I know I haven't been around for a while! Anyways, recently bought 12 Ram 2500 6.7 HO 4x4, mileage 281,000! I know the truck personally and good friends with the guy I bought it from. Was driving down the road the other day about 65mph and it started acting like it didn't wanna go, Pulled in grabbed a bite to eat, get back in and it was little hard starting, and kinda sluggish in o/d. Get back to the shop and decided to replace the fuel filter, now it wasn't dirty and kinda slow to fill back up, so replaced intank lift pump have good fuel pressure and flow to filter. Truck will try to hit once and that's it, accidently cleared the codes but do remember that it said something about low fuel rail pressure. Hooked up diagnostic tool again and monitored fuel pressure it's running about 4,000 at starting but will not start, no tuner, bone stock. Any ideas where I need to look? I'm outta ideas!!!

i thought the 12's had 2 fuel filters...  a water separator at the back and another somewhere else. 

even still you need closer to 5K rail for the injectors to fire. might be time for new injectors, there is a return flow rate test you can do to determine this. I'm thinking you have to much return flow. 

I thought the dual fuel filters started in 2013 with the DEF motors. 

 

I've heard numbers from 3500-5000 for the minimum pressure needed to fire. 

 

You can unplug the FCA on the CP3 and that will allow full fuel. See what it cranks at or if it starts. If it does start don't let it idle, shut it off as the rail pressure will be very high. 

 

 

 

 

Ok I’m only getting 400 psi when cranking unplug the fca an still nothing. Cracked fuel line going to the rail and no flow. 

Can you hear the lift pump cycling?

23 hours ago, Killer223 said:

might be time for new injectors, there is a return flow rate test you can do to determine this. I'm thinking you have to much return flow. 

 

My thought's exactly. 281k on possible stock injectors is rather excessive. Typically replacements are suggested at 100-150k miles on average. Some people get away with more mileage but it's not safe.

 

I've got to ask has the grid heater light been staying on after you start?

53 minutes ago, AH64ID said:

Can you hear the lift pump cycling?

Lift pump is working....replaced it with new oem lp. 

No light goes off and stays off. 

31 minutes ago, Mopar1973Man said:

 

My thought's exactly. 281k on possible stock injectors is rather excessive. Typically replacements are suggested at 100-150k miles on average. Some people get away with more mileage but it's not safe.

 

I've got to ask has the grid heater light been staying on after you start?

Light goes off and stays off till recycle 

4 minutes ago, mrtowman4u said:

Lift pump is working....replaced it with new oem lp. 

No light goes off and stays off. 

Light goes off and stays off till recycle 

 

It doesn’t sound like injectors, as the CP3 should still output fuel to the injectors. If you’re not getting fuel to the rail the issue is before the rail. 

 

Disconnect the the fuel supply to the cp3 and put it into a jar or something. Turn the key to on, then bump it to start and release. The LP should run for ~30 seconds and you should get quite a bit of fuel. This will verify you don’t have a blockage issue. 

Being the grid heater light isn't on then the ECM has not detected high return fuel flow. 

 

I did have one truck that had a loose connector tube and was pumping the rail pressure into the return rail. After I tighten the connector tube up the truck started and ran great. 

2 minutes ago, Mopar1973Man said:

 

I did have one truck that had a loose connector tube and was pumping the rail pressure into the return rail. After I tighten the connector tube up the truck started and ran great. 

 

It sounds like he’s not getting fuel to the rail, so it seems to me the issue is in the CP3 or supply line. 

 

Kind of like why I got that FCA for sale in the classifieds. I thought the same thing on my particular case. Change the lift pump, FCA and still cold start it would run but after then warmed up the rail pressure would fade till it stalled. The #4 connector tube was just loose enough that cold it sealed good enough that rail pressure built up to start but as everything expanded and warmed up the rail would drop to below 4k and stumble and then die out. Won't start until cold again. once the tube was tight problem disappeared. So hoping, in this case, something simple allows the rail pressure to bleed out in the return rail. Just crazy thought being I did experience this one. 

Yes that can happen, but he cracked the line to the fuel rail and got nothing. That’s not caused by an injector or crosstube. 

Edited January 9, 20187 yr by AH64ID

Hmmm... I'm out of ideas I gave it my best shot... 

31 minutes ago, AH64ID said:

 

It sounds like he’s not getting fuel to the rail, so it seems to me the issue is in the CP3 or supply line. 

 

I’m gojng to do a cp3 flow rate in the morning! And also check the supply line flow.

take the CP3 supply line banjo loose the top of the CP3, bump starter see how much fuel comes from said line. 

if you have fuel, then the next thing is the pressure relief on top of rail, you can take it off and plug it or some times they can stick open. if you get fuel from the pressure relief banjo, then it needs to be replaced. 

fallow this video for instructions. report back with results. 

I'll add if you take the banjo off the return port and there is more than a slight dribble, it's injectors. 

 

Edited January 9, 20187 yr by Killer223

OK so this afternoon, I took the fuel supply line off of the cp3 and I'm getting a good rate of flow. Took the banjo bolt out and I'm getting minimal flow out of the pump. Unplug the fca and it's acting like it wants to crank but no start. 

Looks like the issue is with the CP3. There are several components it could be. 

 

Personally I would call Todd at TC diesel. He knows his CP3’s and common rails. 

Just now, AH64ID said:

Looks like the issue is with the CP3. There are several components it could be. 

 

Personally I would call Todd at TC diesel. He knows his CP3’s and common rails. 

Who is Todd at TC Diesel?

 

6 minutes ago, mrtowman4u said:

Who is Todd at TC Diesel?

 

 

 

He is active on TDR and has a diesel repair shop that specializes in the HPCR fuel system.  

 

http://www.tcdiesel.com/

I talked to Todd several times, and checked everything out that he suggested. He thinks I have a gremlin living in it. Still no start, but getting fuel to rail an Injectors. I'm at my witt's end with this truck!

 

Crazy idea... I'm reaching here... How about alternator test for AC noise and possible ECM issues because of AC noise damage? Yes you can pull the alternator and have it tested but it might give a clue to if the ECM possible was damaged by excessive AC noise. I've now had one report that proves that AC noise is possible on newer trucks.