No start condition: Help me figure out what's left...

My66dodge · **Posted:** Sun Feb 10, 2019 7:45 pm

I don't remember the exact spec for the r428 but with the rail pressure under 1000psi it won't start, a common rail will run up to 32000psi on some of the new ones and the minimum is usually somewhere around 1000-1200 to start from what I have seen, lower and the best you will get is a sputter. I could check alldata or my fsm but with less than 1k cranking I believe the restricted fuel filter and running hard killed your pump. I run into it all the time on the Duramax's when they go over on their fuel filters and it inverts the seal and they crap a pump. That's why I always tell my customers I recommend an oil change at 5k and fuel filter every other oil change or every third at most, I deal with lots of contractors who rely on the trucks to work hard and always run well, all it takes is one tank of bad fuel to kill a filter and filters are cheap pump insurance.

Sounds like you need a pump, I can't be sure without it being at my shop but it sure sounds like it

dgeist · **Posted:** Sun Feb 10, 2019 8:56 pm

How would you test that? Measure flow over time with a certain amount of resistance? Hopefully it's not just a matter of "swap parts until it gets better". I really can't afford that right now.

My66dodge · **Posted:** Sun Feb 10, 2019 9:48 pm

I don't recommend the swap parts method... I like to test prove repair. I would check the wiring from the rail pressure sensor to the ECM to make sure it's good, then check inputs to the sensor like power and ground, then check what the cranking pressure should be and compair it with the actual, before you crank it over make sure you pump the primer till it gets hard to make sure there is no air leaks. If the rail pressure is less than spec it needs a high pressure pump, I do the same on all diesels and GDI I repair, last week I had an 11 camaro v6 that wouldn't make more than 100 psi on the rail and didn't have spark to half the engine, it should be atleast 1000 but I like to see 1200-1500 on those engines, so I replaced the high pressure pump and the car ran great, the last "mechanic" threw 3 new coils at the right side and replaced the in tank low pressure pump... The problem is when the rail pressure is too low this car shuts off one side to use the pressure it has to run the engine on half to allow the customer to get to the shop. High pressures generally either fail abruptly or have power loss for a short time then fail and no start.

rankom · **Posted:** Sun Feb 10, 2019 9:52 pm

what about you try ordering that tool i was mentioning earlier and try capping those injectors one at a time. maybe one of them is dumping fuel into the cylinder. however i could be wrong.

My66dodge · **Posted:** Mon Feb 11, 2019 10:45 am

I just checked alldata this morning after I got to work and it says it should be able to hit 3400+ psi after a few seconds of cranking. If you have proved out the rest of the system you have a bad pump, I can not be for sure as I do not do diagnosis over the phone or internet so this is just info.

WWDiesel · **Posted:** Mon Feb 11, 2019 12:26 pm

Looking at this objectively,
Fuel Rail is not building proper pressure to start engine. :dead:

Some Possible causes:

(you have ruled out fuel dumping out the return lines of each injector by disconnecting the return lines and observing while trying to start)

(one bad injector dumping rail pressure into a cylinder, *has not been ruled out)

(ruled out by swapping out a complete rail assembly which you have done)

(ruled out by swapping complete rail assembly which you have done)

(ruled out by unplugging so all fuel will go to rail)

(can be changed out)

(based on your tests, it appears CP3 is sending plenty of fuel to rail but still not building proper pressure. *still could be the culprit?)

(not very likely since it does appear to be pumping plenty of fuel volume based on the tests you have performed?)

(ruled out by inspection and color of pins)

(you have ruled these out as not the problem)

(*always a possibility)

(ruled out by replacing sensor)

(*has not been ruled out?)

*looks like your down to about 4 possible items that could be causing the "No Start" condition? :banghead:

thoughts anyone

Mountainman · **Posted:** Mon Feb 11, 2019 1:28 pm

I agree with WW. Do the CP3 last as just about every time someone swapped one on this forum it wasn't bad! I have a pile of them on the shelf because everything else fails first.
Was the jeep going in to limp mode, or just had reduced power?
And didn't you say you had some electrical gremlins? If so, I would start by cleaning the body ground that is below and forward of the battery, and then all other grounds that have to do with engine/ecu.
-oh, was the temp gauge ever acting weird?

After you answer these questions I'll rethink what parts could cause these symptoms.

dgeist · **Posted:** Mon Feb 11, 2019 10:08 pm

Mountainman wrote:

I agree with WW. Do the CP3 last as just about every time someone swapped one on this forum it wasn't bad! I have a pile of them on the shelf because everything else fails first.
Was the jeep going in to limp mode, or just had reduced power?
And didn't you say you had some electrical gremlins? If so, I would start by cleaning the body ground that is below and forward of the battery, and then all other grounds that have to do with engine/ecu.
-oh, was the temp gauge ever acting weird?

I believe it was reduced power anything over about 30 mph would simply die out and stall (hence the suspicion of inadequate fuel), not an actual limp-home. There were no additional codes in the ECU.

The electrical gremlins were things like Sirius/XM rebooting while cranking and so forth. Nothing really strange. I've had issues like that before when batteries were failing, which is why I had the battery checked, and it did indeed need replacing. Temp gauge never had issues.

With regards to WW's list. I'm confused by 5/6. I thought the plug just in front of the intake flapper assembly was for the FCA solenoid? I didn't know you could test the overflow valve separately...or are these two linked together behaviorally.

Agreed that I haven't validated fuel being dumped into cylinder, nor camshaft sensor. Can the latter actually prevent pressure build-up in the rail, though? My understanding is it doesn't get used until after the engine fires.

WWDiesel · **Posted:** Mon Feb 11, 2019 11:30 pm

Hopefully to clear up any confusion?
Items 5 & 6 in my post.
5. mechanical valve on side of CP3 pump)
The Cascade Overflow valve regulates how much excess fuel is used for lubrication inside the pump and how much is returned back to the fuel tank via the drain manifold and return hose. It also helps in removal (limited) of air in the fuel.

There is only one electrical connection on the rear of the CP3 injection pump.
6. Fuel Quality Solenoid (sometimes also incorrectly referred to as the Fuel Pressure Regulator or Fuel Control Actuator)
----It is located on the rear of the CP3 injection pump and is an electronically controlled solenoid valve. The ECM controls the amount of fuel that enters the high-pressure pumping chambers by opening and closing the FQS based on a demanded fuel pressure. The FPS (Fuel Pressure Sensor) on the fuel rail provides the actual fuel pressure measurement. When the Fuel Quality Solenoid is opened, the maximum amount of fuel is being supplied to the fuel injection pump. Any fuel that does not enter the injection pump is directed to the (5) Cascade Overflow valve.

Fuel enters the fuel system from the electric fuel transfer (lift) pump if you have an intank pump installed. Fuel is forced through the fuel filter element and then enters the low pressure Fuel Pump/Gear Pump, which is attached to the rear of the fuel injection pump. The Fuel Pump/Gear Pump is a low-pressure fuel pump which is also used to pull fuel from the fuel tank if no lift pump is installed. Fuel enters the high pressure section of the fuel injection pump from the Low pressure fuel pump as supplied and controlled by the FQS.

Fuel entering the high pressure injection pump is pressurized to between 300 -1600 bar by three radial pumping chambers. The pressurized fuel is then supplied to the fuel rail.

More on the FQS:
Fuel Quality Solenoid

The solenoid is pulse-width controlled by the ECM and meters the amount of fuel that flows into the high-pressure elements inside the high-pressure pump.
The solenoid is inactive up to 30 seconds after the ignition switch is initially keyed to ON position to allow maximum fuel pressure to the fuel rail during cranking and start up. ECM assumes FQS valve control when CPS signal and rail pressure are within acceptable limits

The ECM determines the fuel pressure set point based on engine sensor and rail-pressure inputs. If the actual fuel-rail pressure is too low, the ECM commands the solenoid to allow more fuel to flow to the high-pressure pump. This minimizes the difference between the actual fuel-rail pressure reading and the set point. The ECM will also operate the solenoid to delay fuel, reducing flow-rate, if the fuel-rail pressure becomes too high.
The FQS valve is commanded open by the ECM to allow the high-pressure pump to build maximum pressure (23,206 psi).
Thus, rail fuel-pressure can be increased or decreased independent of engine speed

GordnadoCRD · **Posted:** Tue Feb 12, 2019 3:49 am

Regarding FCA.. With the CRD it stands for Fiat Chrysler Automobiles, and is usually spat out in derision.

The term Flow Control Actuator is never used by Mopar in reference to the CRD, the reason being the confusion that it's causing here, as this engine has a Flow Control Valve, (FCV) that is completely different, but sounds confusingly similar.

To avoid confusion, with the CRD, the proper term is FQS. Fuel Quantity Solenoid. In the CRD case, it most perfectly describes what it is, and what it does.

The FQS, WWDiesel has properly described where it is, what it is, and how it does it. My only modification is that it's properly called FQS rather than FAC or FCA, and that it's the component that the ECM uses first to make quick adjustments to correct under-spec rail pressure. As far as hydraulic circuit location, it is positioned between the Cascade Overflow Valve and the high pressure pump unit. It's static condition is 100% max flow. It's fully energized condition is as close to no flow as it can get.

The one on the rear end of the fuel rail is FPS (Fuel Pressure Solenoid) (releases fuel when the pressure is out of spec TOO HIGH) Also an electronically (PWM) controlled valve. It's static condition is OPEN (no fuel pressure can build), and the energized condition is CLOSED (MAX pressure)

The one in the middle of the fuel rail is Fuel Pressure Sensor. Instantaneous condition information, observed by the ECM, and used to command solenoid adjustments.

Sensors tell the brain (ECM) what is happening and every environmental parameter it wants to know, so it makes the right decisions regarding individual commands.
Solenoids, relays, valves, etc, turn the resulting commands into actions, and the cycle continues as long as the engine is running correctly. (Closed loop condition) A couple years back I read somewhere how many times per second the ECM reads info and makes adjustments, and it was pretty astounding. I can't remember exactly at this time, but many hundreds, perhaps thousands, but for all of the things it watches and adjusts, I was impressed. And it's OLD tech at this point! (but then, so am I :frankie:

)

The Cascade Overflow Valve (COV) is not an electronic component. It is a mechanical valve that directs fuel flow into, through, and (both directly and indirectly) out of, the CP3, and serves a couple of functions. The one WWDiesel doesn't mention, is removal (limited) of air in the fuel. It works on the same principle that FASS units use (air bubbles in pressurized fuel are much smaller, and easier to bleed away)

Cascade, refers to the fact it deals with multiple processes depending on pressures provided
Overflow is due to it directly returning all (most) excess fuel back to the tank (or pre-LP pump in other applications) As well as all of the lubrication fuel and inter-component leak-by fuel. It is in this function that a limited amount of air-in-fuel can be returned to the tank. I should say that although I use the word limited, it's capability much greater than one would imagine, and If you're having air-in-fuel drivability issues, you're sucking more than a few little bubbles.

0-44 psi, it does pretty much nothing other than pass fuel through. (cranking fuel supply. No restriction)
45-72 psi fuel is passed into the internal lubrication passages. (to supply lubrication before pressure is built) Hydraulic Circuit diagram, between the LP pump, and the CP3 body/lubrication passages
73+ psi fuel is now able to pass to & through the FQS, into the high pressure pump cylinders, through the check valve, and out to the fuel rail. Hydraulic Circuit diagram, between the LP pump and the FQS.
When working, the CP3 in our rigs will progress through these steps, easily, under 2 seconds. Properly functioning in NEW vehicle condition should be within 2 revolutions.

At this point, I have to apologize and admit I've had a dissection project I've not gotten around to for about a year and a half. That is to go through a CP3 in detail, like I have with the FQS, the FPS, and the fuel rail.
Thermorex donated it. I have it. I just have been kind of overwhelmed with other things, mostly Doctor-related, considering my daily energy and pain levels. It has been kind of an inexcusably long time though. My goal is to go through it, with pictures, etc, and see if I can determine why it was under-performing.

WWDiesel · **Posted:** Tue Feb 12, 2019 1:32 pm

Thanks Gordon for the correct nomenclature for the FQS valve, I have seen it called all three different names depending on where you look or read. :banghead:

Updated my post where necessary.

Here is a cutaway-diagram of the CP3 with parts identified that is pretty good.
I changed a couple of the names in the list to agree with the corrected identification

Mountainman · **Posted:** Tue Feb 12, 2019 2:05 pm

dgeist wrote:

Mountainman wrote:

I agree with WW. Do the CP3 last as just about every time someone swapped one on this forum it wasn't bad! I have a pile of them on the shelf because everything else fails first.
Was the jeep going in to limp mode, or just had reduced power?
And didn't you say you had some electrical gremlins? If so, I would start by cleaning the body ground that is below and forward of the battery, and then all other grounds that have to do with engine/ecu.
-oh, was the temp gauge ever acting weird?

I believe it was reduced power anything over about 30 mph would simply die out and stall (hence the suspicion of inadequate fuel), not an actual limp-home. There were no additional codes in the ECU.

The electrical gremlins were things like Sirius/XM rebooting while cranking and so forth. Nothing really strange. I've had issues like that before when batteries were failing, which is why I had the battery checked, and it did indeed need replacing. Temp gauge never had issues.

With regards to WW's list. I'm confused by 5/6. I thought the plug just in front of the intake flapper assembly was for the FCA solenoid? I didn't know you could test the overflow valve separately...or are these two linked together behaviorally.

Agreed that I haven't validated fuel being dumped into cylinder, nor camshaft sensor. Can the latter actually prevent pressure build-up in the rail, though? My understanding is it doesn't get used until after the engine fires.

I would think the ecu would want to know the cam is ok (mechanical failure) before it signaled the FPS to build pressure? But, you're right, the symptoms sure sound more like fueling. Perhaps you were feeling the cam sensor failing? Easy to swap that one and the FQS especially if Jim can lend you them.
Edit/in addition: if you haven't verified the 5v (ish) is getting to the FPS, then I would do that. Even if the wire is good, and ECU pin looks good still leaves the chance that the connection at the ECU isn't necessarily open. I would imagine that you could just pop off the connector at the FPS and ground the negative pin, and put a meter on the other pin. The experts will correct me if I'm wrong

But, then again, my experience with the FPS is that it's all or nothing, no fuel restriction feeling, just instant death of engine. Hmm

Mountainman · **Posted:** Tue Feb 12, 2019 2:22 pm

All that rambling means I'm leaning towards the FQS, but the cam sensor only takes minutes to swap just in case.

dgeist · **Posted:** Tue Feb 12, 2019 2:32 pm

Mountainman wrote:

All that rambling means I'm leaning towards the FQS, but the cam sensor only takes minutes to swap just in case.

Thanks. As I track (and learn), I'm basically at those two things, or a completely jammed injector, or a dead CP3. I'd much prefer if the problem turns out to be a sensor.

Cam position sensor is plainly visible. FQS looks like it's just 3 allen bolts down near the intake elbow. Am I missing something or is it that easy, too?

Dan

WWDiesel · **Posted:** Tue Feb 12, 2019 2:44 pm

dgeist wrote:

Mountainman wrote:

All that rambling means I'm leaning towards the FQS, but the cam sensor only takes minutes to swap just in case.

Thanks. As I track (and learn), I'm basically at those two things, or a completely jammed injector, or a dead CP3. I'd much prefer if the problem turns out to be a sensor.
Cam position sensor is plainly visible. FQS looks like it's just 3 allen bolts down near the intake elbow. Am I missing something or is it that easy, too?
Dan

You are correct, only 3 small bolts to R&R the FQS.
I still doubt a bad CP3 as that is a very extremely rare occurrence indeed.

I think you are correct as to being down to three items, bad injector, bad FQS, or possibly bad cam sensor?

Found this in the FSM of interest in your case:
If no signal is supplied by the camshaft position sensor, the vehicle will not start because cylinder order can not be detected. If the signal is lost while the engine is running the vehicle will continue to run until shut off.

This picture shows the bolts clearly:

Mountainman · **Posted:** Tue Feb 12, 2019 2:47 pm

dgeist wrote:

Mountainman wrote:

All that rambling means I'm leaning towards the FQS, but the cam sensor only takes minutes to swap just in case.

Thanks. As I track (and learn), I'm basically at those two things, or a completely jammed injector, or a dead CP3. I'd much prefer if the problem turns out to be a sensor.

Cam position sensor is plainly visible. FQS looks like it's just 3 allen bolts down near the intake elbow. Am I missing something or is it that easy, too?

Dan

Yup, some pre cleaning and probably want to move some stuff out of the way. I think Flash has swapped one. I never have because I have yet to see one fail.
*I thought they were torx?

WWDiesel · **Posted:** Tue Feb 12, 2019 3:00 pm

Mountainman wrote:

*I thought they were torx?

Yes, the ones in the picture are definitely small torx screws...

GordnadoCRD · **Posted:** Wed Feb 13, 2019 3:57 am

WWDiesel wrote:

Thanks Gordon for the correct nomenclature for the FQS valve, I have seen it called all three different names depending on where you look or read. :banghead:

Updated my post where necessary.

Here is a cutaway-diagram of the CP3 with parts identified that is pretty good.
I changed a couple of the names in the list to agree with the corrected identification

Wow. I'm not sure what application that diagram is for, but it is not the one used on our domestic 05, 06 CRDs.
Several components are in the wrong place, and incorrectly named. And yes, it sucks that nomenclature is different between manufacturers that use some version of this pump.
It has 3 cylinder pumps so it COULD be a CP3, but it's definitely not the one ours uses.

WWDiesel · **Posted:** Wed Feb 13, 2019 1:49 pm

GordnadoCRD wrote:

Wow. I'm not sure what application that diagram is for, but it is not the one used on our domestic 05, 06 CRDs.
Several components are in the wrong place, and incorrectly named. And yes, it sucks that nomenclature is different between manufacturers that use some version of this pump.
It has 3 cylinder pumps so it COULD be a CP3, but it's definitely not the one ours uses.

It is for the Dodge diesel and yes it is a Bosch CP3 but should be very similar to ours?
If you can find a good cut-a-way drawing for our specific CP3 with parts identified, please let me know.

rankom · **Posted:** Wed Feb 13, 2019 10:57 pm

hi guys this thread reminds me of australian 02kj that we never figured out. mprop valve is a good starting point at this time as everybody seems to lean that way. personally i would like to see more testing. maybe injector testing. also we dont know the condition of the exhaust valves.

No start condition: Help me figure out what's left...

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