My rail pressure at idle, either standing still or coasting at speed, has fallen from a steady 7/8k to 4/5k, every once in a while it will bounce back up to 7k? A few times it has dropped to "0", engine stutters and almost dies before it recovers. As long as I'm feeding it fuel, truck runs fine, WOT is a bit low at 23/24k, usually a solid 25/26k.

I have removed the EZ, TST is off, and I put the Smarty back to stock, same symptoms. I have noticed immediatly after starting, I hear a clicking sound from the dash, it will continue clicking intermitently for about 2 minutes before it stops. When it clicks, my rail pressure gauge jumps about 1k. I thought it might be the grid heater relay cycling, but the alternator gauge does not budge.

I am thinking maybe my Walbro lift pump is failing. I have never experienced a lift pump failure on my CR before, so I do not know the symptoms, I also do not have a fuel pressure gauge, but the Walbro does seem to be running "uneven", not totally steady. I'm not sure how the lift pump relates to the clicking under my dash, sounds like it is coming from the right side of the dash.

What do you think? I would be thankful for any input. Jess

 

The clicking is probably the grid heater. Mine is quite noisy, and when I ran a RP gauge I saw it jump about 1K whenever it was cycled, on or off.

The walbro would change pitch with the grid heater as the grid heater drops the voltage to around 11.8-12.5.

As for the RP issue it could be an FCA.

 

Possible FCA going out,Does the fuel rail
pressure fluctuate more than +/- 500 PSI? A good system will have actual fuel pressure that is +/- 500 PSI from the set
point. (Example: If the fuel pressure set point at idle is 6500 PSI, the actual fuel
pressure on a good system is expected to be between 6000 - 7000 PSI). If fuel
pressure variation is excessive, an audible surge will be present. If the variation is
severe, a slight engine speed variation may also be noticed
part number 05183245AA Actuator

 

Thanks for the reply guys!

AH64ID, everything you say tracks with what I am seeing, I needed the reassurance of what I thought was taking place, Thanks.

The FCA was my first thought also, I installed an Arson III last August and it has performed flawlessly......

I left a message today for Shane at Wicked Diesel, and to his credit, he called me back this afternoon. Because my rail pressure is dropping all the way to "0" sometimes, he seemed to lean towards the lift pump. I still have the stock FCA, so if tomorrow is decent, I'll swap them, see what happens.

Big Iron, Thanks for the Dodge part#, and yes, rail pressure is bouncing about 500psi to 1k @ idle, according to my Dipricol gauge.

What do you think, anyone who has had an FCA fail, did your RP go to zero?

Jess

 

I have never seen one go to zero, maybe you have something else going on. Check the limit valve if it is leaking that could cause fuel pressure to drop really fast also. Check if Fuel pressure sensor read 0 psi engine not running key on? Clicking possible fuel pump relay installed left side engine compartment on firewall. Should have a power feed to battery with a fuse installed if truck had retrofit pump installed. Did you own truck since new? I have seen those relays go bad or corrosion at the battery causes a problem.

 

Today I went out to change the FCA, put the stock one back on. I had to move my truck first, and I noticed I had CEL, P0251 = INJECTION PUMP FUEL METERING CONTROL "A" MALFUNCTION, or INJECTION PUMP FUEL VALVE FEEDBACK depending which list you read.

I cleared the code with my Smarty and changed the FCA. My rail pressure seems more stable, but still low at idle, 5k, when I put it in gear it will go to about 6/7k, WOT is a steady 25k. While cruising rail pressure is stable, but if I let off the throttle and coast rail pressure drops to 4k.

I have not gotten another code yet, and the stock FCA seems less irratic than the modified one from Wicked.

Has anyone dealt with this code P0251, could it be a rail pressure sensor, TPS? My rail is capped so it's not the relief valve. I wonder if it still could be my lift pump, I am going to pinch off the return line on the Walbro and see if it affects rail pressure at ldle.

 

Pinching the return line was not a good idea, it blew my lid off the fuel filter canister, don't know yet what damage, will update in a few.

 

Ok, no damage, just pushed the o-ring out, put back all good. Now clean up the mess, I guess my lift pump is good.

 

Yeah the filter lid will blow at 30psi...

Well it seems the FCA may have been the culprit afterall. It's 4-5K normal idle pressure on an 03?

 

I not sure what's normal... my truck has always been 7k at idle, but I have had the EZ since I drove it off the lot when new. I re-connected the EZ today, still 5k at idle?? I have been told I should get a spike in rail pressure when I shut it off, there is a slight jump in the needle, but nothing measurable.

I am not sure what P0251 "INJECTION PUMP FUEL VALVE FEEDBACK" means. Is it the rail relief valve? I capped my rail with a solid bolt, the same length as the banjo bolt I removed. Do you think the rail relief valve could have opened, and fuel is flowing around or past the solid bolt? What is the length the bolt should be, to hold down the valve as opposed to just blocking it's path?

I think I better go back and re-torque all my cross tubes also, I have no fuel in my oil, so I'm pretty certain I don't have a cracked tip or body, plus the truck still runs good any time your applying throttle.

Anyone have experience with the P0251 CODE? Thanks. Jess

 

At this point its beyond by depth of knowledge.. I haven't seen the code before.

 

TWEST on TDR thinks maybe a sensor or the cascade valve?

Here is a list of codes for 03's

http://www.turbodieselregister.com/f...s-p-codes.html

 

I replaced my Arson cascade valve with my factory valve this morning and my rail pressure is now 6k at idle in neutral and jumps tp 7/7.5k when I place in gear. I let it run for 1/2 hr, no change. The factory FCA is still installed also, so I will have to swap the Arson back in to see how it behaves.

The weather will not permit me to do any WOT runs, but right now the trucks seems to be close to normal. I will call Shane at Wicked tomorrow, to get his take on this.

Thanks to all who gave me input, Jess

 

My 2003 (305/555) is @ ~5,000 psi at idle in neutral (range 4,500 - 5,500 psi). The idle readings don't change whether or not a pressure box and/or Smarty and/or TST is in the picture.

Another person I know with a 2004 (305/555) automatic shows ~5,000 psi in Park and ~7,000 psi in gear with brake applied.

 

Until my truck almost died, I guess I didn't really notice the difference between idling in neutral or gear. I usually watch my rail pressure while driving, so it was in my mind that 7k idle was the optimum whether in gear or not.

But changing the cascade valve back to the factory unit, definitely made an improvement in rail pressure, as stated earlier, I now have to swap the Arson FCA back into the system, because by changing both units from the Arson to stock improved the rail pressure problem. I still need some more driving time to be sure. Still have not thrown another P0251 , so I bekieve one of the two items are the culprit.

Thanks metal_miner