RAM Cummins 6.7L Low rail pressure

A basic diagnostic on a 2016 RAM Cummins 6.7L. Diagnosis focus is on the low pressure side where fuel filters have not been replaced. Common rail overview.

[landonhinkle]

Thank you for explaining this system to me better. I have a late model 2012 which is a pain in the ass don't buy one. It just shut off on me driving down the road one day. Ever since then it's just cranked won't fire. I started with the fuel filter so that made me feel good while watching your video. Then I changed the solenoid in the gear pump housing on the back of the CP3 pump then I changed the fuel rail pressure sensor then I changed the fuel rail check valve I have changed all the fuses, I have changed the position crankshaft sensor, I have changed the sensors on the trans, and I still cannot get the damn thing to fire. And it has not once through any codes. I replaced the injectors and the lines whenever I put a new head gasket in it and upper block cylinder head about 10 12, 000 Mi ago.

[sts.]

all about your Maintenace folks, stay on top of it.

[JesusCastillo-vs]

I got the low fuel pressure code after changing both filters i think the truck got some air because it wouldn't turn on after i let some air out it cranked right up but started with the check engine light now once it gets to normal temp will loose power and wont go over 10 mph whay could be the cause for rthat

[gavin]

I have a 2014 Cummins, it has a rough idle lope when cold, then goes away after about 30 seconds of idling, then comes back after the engine is back up to operating temp. Discovered it is running between 3900 and 5200 psi at idle when 4700 is commanded replaced fca. No change. Runs completely fine otherwise, problem only at idle. Unplugged fca and the computer commanded 5200 and it was able to hold around that and idle fine. Restarted the truck and it commanded 4700 and rough idle came back.

[bjen]

@Tony Salas --- What about excessively cold weather like here in the North (MN, MI, SD), gelling the fuel causing fuel rail pressure being to low on the low pressure side, which in turn would affect the high pressure side since its starving it for fuel. I could see that throwing some DTC code about rail pressure.

FYI: Not a mechanic, but I still like to know how diesels work and all the in's and out's.

[_Machine_]

awesome video!!! Im having this issue. I replaced my fuel filter on my 12' 6.7 cummins. but never sucked out any sediment(My mistake). still have the 0191 code, so instead im going to eliminate the oem crappy set up and get an airdog.

[sharee-]

After replacing my fuel filters with two filters from Diesly I got a light saying water was in my fuel, I drained some fuel and there was NO WATER in it. Then I replaced the water separator sensor and the light went off. Drove 1 day with no issue next day, got a code P0087 low fuel rail pressure. I normally use Mopar fuel filters, I've also noticed my lift pump doesn't seem to be sounding off very loudly as usual. I'm gonna replace the lift pump and put two Mopar fuel filters back on.

[geriatricginger]

I'm battling an issue with my 08 6.7L Cummins right now, of fuel de-rating under load, yet I get no codes. So in the worst method possible (throwing parts at it) I've made no headway.
Under 60-70% throttle, 5th or 6th gear, say, climbing a mountain pass, commanded is at 22-23K. Rail Pressure (RP) is at same as commanded, then starts to drop as a little more throttle is input. RP drops to around 9-11k, and after 5-10 secs, derate counter increases by one, and the power is drastically reduced.. After about 30-40 secs, after backing out of the throttle, it will re-gain it's power and business as usual (until the next time).
I've replace filters, fuel rail, RP pressure sensor, relief valve, checked crossover tube torque/re-torqued tubes, replaced in-tank lift pump, etc., but problem still remains.
New Bosch injectors about 3-4 yrs ago, but only about 8-10000mi on them (replaced set because I had a failed injector).
Any way, I get no codes, but cannot seem to find this fuel de-rate problem..
Thoughts? Thank you very much.
Truck is tuned and has had same tune on it for 10 yrs.

[TheMemo]

i have the same problem I took it to the dealership they say was the fuel pump they installed as fuel pump the check engine light went away is running but it doesn’t have the same power like I used to. When I put my scanner before I took it to the dealership is low pressure rail sensor

[themotofixery]

I just got done installing a grid heater delete on my 2017 ram 3500. This involved removing the lines from the fuel rail. Now I have a code p0087 saying fuel rail pressure too low. The engine runs but stalls in a minute or two. It's asking 5000psi snd getting 1200psi. This varies with rpm obviously. I see no leaks externally. Someone suggested injector feed tubes could have become loose when removing the lines from the rail. Is this possible you think? Filters are new. Any other idess?

[frankelias]

Hi Tony, I'm Frank from Brasil, I'm working in this Jeep Grand Cherokee V6 diesel, do you know if there is any type of a regulation on The DRV valve or you just put it on The rail and that's it.

[toddkovacs]

great info tony have a 2014 3500 ram 6.7 getting low rail pressure code p0087 when first drive of the day command pressure and actual are pretty good until about 3 miles and warmed up then get code and command will demand 22k but i cant get over 14k on actual rail pressure! lift pump psi is good could it be the pressure relief valve getting weak? or something else return fuel test of the injector return line is a steady flow out the hose is this correct please any help on what to check... thanks

[edwardjayfix]

Great video!! Quick question….Have you ever had a QSB6.7 Cummins intermittently smoke under load, accompanied with a rpm surge, under load, But runs fine with map sensor unplugged? Any insight appreciated.

[mikehastings]

I just replaced every component including a cp3 conversion in a 2020 6.7, and still have low fuel rail pressure... help

[AngelLopez-vjip]

I change the filter just have one but don’t start the only part I don’t change is the injectors that’s my next step the scanner says low pressure in common rail I don’t understand what happened have 2 months in the back of my yard need help

[reidhoward]

Where is Fuel Rail Pressure Sensor located on a 08 6.7 Cummins?

[-robklein]

just did fresh rebuild on a 12 cummins 6.7..will drive but when given heavy throttle rail pressure drops to 4000psi from 18000... injectors all tested, new feed tubes.. any ideas? runs, idles and revs fine.. only happens while driving?

[domonickcolletti]

Tony i need your help. I have low rail pressure. I slapped a new Fass lift pump on and an upgraded cp3 from fleece performance. There’s no visible fuel leaks and there’s no fuel in the oil. I still have the problem. The most i get on the rail is 13500 psi when commanded is in the 20’s

[derrickmorrow]

I have a 2014 ram with the 6.7, it died on me going down the highway and now have a crank no start issue. I replaced the filters and confirmed my lift pump was getting pressure. My monitor says commanded pressure with the key in on position is 4641 psi and the actual is only 107 psi. Is it safe to assume the cp3 is bad or should i be looking at fca or rail pressure sensor?

[justinberrett]

Hi, thanks for the video. I have a 2016 ram 3500 6.7 Cummins with 120000 miles. My truck sometimes has a rough idle and it bounces from 550 rpm to 800rpm. There are no codes. Then other times without changing filters or anything it will idle correctly from 695 rpm to 703 rpm. Then a few days later goes back to rough idle. I’m new to diesel world. What do you think could cause it? Your input is appreciated. Thanks