I will take too! The picture of the sealing surface and o-ring would be helpfull. Thanks!

cquestad@hotmail.com

 

You've got mail!!

 

"You remove the return line from the top of the relief valve and screw in this special fitting. Attach a piece of hose to this fitting and run it into a bucket. Crank the truck. Unplug the pressure sensor causing the rail to go to max, simulating WOT, and measure the amount of fuel that comes out of the hose. You should get XX ML of fuel in so many seconds. If you measure more, your valve is bad.....and no, the relief valve does not have to pop to get fuel out of the hose. There is almost always a little fuel getting by that valve. That is why you measure it."

This is wrong.

When you disconnect the rail sensor, the CP3 is going to go to max pressure. It will open the relief valve, unless it is stuck. The thing to check at this point is the rail pressure the valve opened at, not the flow rate.

The flow rate is determined by the strength of the CP3. If you get no flow your CP3 is bad, assuming the relief valve is not stuck.

The relief valve should flow no fuel until it opens.

A better way to test this in my mind would be to make up a test line that goes between the relief valve and its return line. Put a visual flow meter in the test and mount it where it can be seen while driving the truck. Say on the front windshield. Hook the truck on the trailer and see what flow there is at high power levels.

 

.....No? Is that just a hunch or did you receive a change to the service manual? I'm sure the members would appreciate only factual information. If you have that to the contrary, we would all (myself included) like to know.....please post it. No hunches though!

When you pull that rail pressure sensor, pressure does go to max. The valve will not open unless you:

(A) Have a bad valve. A good stock valve will not pop during the short duration of the test. There are several tests in the service manual for different parts of the fuel system that requires you to unplug the pressure sensor and send rail pressure to max. A good stock valve will be absolutely fine.

(B) The valve has popped once already and reseated itself. It will pop at much lower pressures from that point on, i.e., when using a pressure box.

If your valve has popped and did not fully re-seat itself, it will be flowing a fair amount of fuel and you more than likely can measure more than the pass-through allowed while at idle.

If that valve opens when rail pressure goes to max, your valve is bad for one reason or another and should be replaced. If it does not open, it is good. Simple as that. We would have to consult with Don M on what the max pressure is that the rail sees when you unplug the pressure sensor as I haven't measured it. He has. It may be lower than your thinking.

You can hook up a DRB and see if commanded pressure is the same as actual, but all this tells you is that you have a problem. It could be the return valve in the CP3, the rail pressure sensor, the relief valve......the list goes on and on. Testing the valve by itself is the only way to verify "it" is the culprit. Of course, if you have a dealer that is willing to just replace it and see if the problem goes away or pull one off of another truck to "try", then more power to them. Definitely less work and not nearly as messy.....if that fixes the problem the first time and no further troubleshooting is required. As an example, Gypsyman had a problem where he had very little pressure in the rail, truck would not go over 55mph, smoked like a banshee. Immediately everyone thinks relief valve as he has played with some pressure boxes. After testing everything, it all checked good. It ended up being a loose injector tube from his recent injector swap causing almost all of the fuel to be returned to the tank. Couple clicks on the torque wrench and all was fine. That could have gotten very expensive if we had just thrown parts at it on a hunch.

The dealers have access to a service manual that is much more in-depth than the manual you see for sale on CD. It lists detailed procedures for testing each individual part of the fuel system. If your dealer has it (they should) and takes the time to actually look it up, they will see these procedures and the special tool that they need to do the test.

 

AK Ram is correct and not pulling stuff out of thin air according to my Cummins HPCR Classroom book with CD Rom (that I purchased from Tech Authority) for the pressure relief valve diagnostic procedure. Granted in the tech book they rely on the DRB3 to do certain things, but AK Ram's description takes this into account.

I actually had cut-and-pasted the procedure for my reply then realized that it was copyrighted so I quickly deleted my post-to-be.

Note the "duhhh" smilie refers to me!

 

Errr... I work with some Bosch authorized fuel shops and we are starting to test CP3s and CR injectors. The procedure mentioned will not test the relief valve, because:

a) if the engine is running at a reasonable RPM (1500+) the output of the CP3 is mostly constant with pressure changes, so measuring the flow rate out the relief valve doesn't tell you anything about the relief valve. It tells you how much the CP3 is pumping.

b) the relief valve is not a flow control device, but a pressure relief device in the event the pressure controller in the CP3 fails or there are pressure spikes. Its purpose is to relieve pressure once the pressure reaches a certain point. Below that point it should not do anything.

I've got the 05 shop manuals. I'll look into what they say when I get time.

This isn't the first time I've seen incorrect literature on this sort of stuff.

 

Could be that perhaps AK Ram and I have '03 versions, while yours is '05? Anyhow, if the test is now in fact different please let us know!

 

I just checked the 05 shop manuals and it doesn't say anything about testing the rail relief valve. I checked chapter 14, Fuel System Diesel and chapter 9 Diesel Engine Service.

Cummins Quickserve does have information on testing the valve. They check flow at either idle or with the Insight tool over riding the pressure control.

Here is what it says

<paste>
Test

If available, run the engine using INSITE™ fuel pressure override test. Otherwise, run at idle. Place the end of the fuel drain hose, or pressure gauge adapter, in a bucket and measure the flow.

Specification At Idle: No flow.

INSITE™ Override: One drop per second (16 mL per minute or 0.5 ounce per minute).
NOTE: If return flow from rail pressure relief valve is greater than specification, restart engine and bring to high idle. The engine will attempt to reseat valve.
NOTE: If Fault Codes 449, 2311, 272, 553, or 2216 are active, do not replace the fuel rail pressure relief valve without first determining the cause of the fault condition. See to the appropriate troubleshooting tree(s).

If the valve does not reseat, replace valve.
<paste ends>

BTW: this is topic "(44-006-061) Fuel Pressure Relief Valve " for my engine, which is serial number 57239207.

No indication is given as to what pressure the Insight tool commands the rail to be, but I suspect it to be high, like the maximum injection pressure for the engine.

Basically, the valve is supposed to be leakproof until it opens to relieve a rail overpressure condition.

 

See, now you have done scared cquestad off. It is a lot simpler than this thread makes it seem bud. Judging by some of your comments above, I believe your "thinking" about it to hard as some comments are accurate and some follow a logical thought process, but reality is not logical. Reality is a little different than what you would expect. Conceding to JStieger's comments that things may have changed a lot between 03 and 05 (I just don't know), I will offer these thoughts and leave it at that.

1) If your 05 shop manual does not have anything on testing the valve, you may just need a better manual. Suggest picking one up from the source JStieger mentioned if you don't already have one. They may have dropped it all together, but not likely. They still use the same part and DC needs a way to test it.

2) Unfortunately, for the average person, I wouldn't recommend relying on anything released by Cummins on the 3rd Gens unless you know enough to spot the differences and compensate accordingly. They are not the same as DC's published procedures. For instance, unless something has changed for the 05 models (very well could have), Insight does not work on our trucks and Cummins repair procedures are only for commercially used Cummins engines that are warranted by Cummins. DC writes their own diagnostic and repair procedures for Cummins products used in Dodge trucks because they change so much. Insight is totally confused and won't talk to the ECM software that DC uses on the 3rd Gens, again, unless something changed for 05 models. Unfortunately, if the information comes directly from Cummins, it may or may not work depending on whether it involves a system that is changed or controlled by DC. It is a crap shoot.

3) Just to clarify, I have the pages (somewhere) of the repair manual outlining the procedures to test the valve. I assure you the procedures I posted, however vague they may be (I don't have the paperwork here to quote verbatim), they are accurate.

Now quit picking on me! I'm a sensitive guy and your hurting my feelings.

 

"1) If your 05 shop manual does not have anything on testing the valve, you may just need a better manual. Suggest picking one up from the source JStieger mentioned if you don't already have one. They may have dropped it all together, but not likely. They still use the same part and DC needs a way to test it."

I've got an official 2005 Dodge Ram shop manual, all 4 volumes. I bought it from my Dodge dealer.

"2) Unfortunately, for the average person, I wouldn't recommend relying on anything released by Cummins on the 3rd Gens unless you know enough to spot the differences and compensate accordingly. They are not the same as DC's published procedures. For instance, unless something has changed for the 05 models (very well could have), Insight does not work on our trucks and Cummins repair procedures are only for commercially used Cummins engines that are warranted by Cummins. DC writes their own diagnostic and repair procedures for Cummins products used in Dodge trucks because they change so much. Insight is totally confused and won't talk to the ECM software that DC uses on the 3rd Gens, again, unless something changed for 05 models. Unfortunately, if the information comes directly from Cummins, it may or may not work depending on whether it involves a system that is changed or controlled by DC. It is a crap shoot."

a) I know that Insight doesn't work on the Dodge 3rd gen engines. Insite is J1939. Our engines are equipped with OBDII or J1850. I'll bet that the Dodge dealers have the same sort of procedure to command the ECM to hike fuel pressure for testing purposes.

b) The Cummins procedure makes good sense. There is nothing to not understand about it, save it would have been nice had they mentioned what pressure the Insight tool sets the rail to.

c) These engines are Cummins first and foremost and our basic engine (ie without EGR) is used in other applications other than the RAMs, albeit with a slightly different harness and programming. I'll believe anything that Cummins writes about them, especially when the information they give is tied directly to the serial number of the engine. I've had Dodge dealers tell me all sorts of things that weren't true about these engines.


"3) Just to clarify, I have the pages (somewhere) of the repair manual outlining the procedures to test the valve. I assure you the procedures I posted, however vague they may be (I don't have the paperwork here to quote verbatim), they are accurate."

I disagree. The rail pressure relief valve is not a flow control device as it would be if it opened significantly at a pressure below its opening pressure. As the Cummins spec states, the leakage should be minimal to nothing even at higher rail pressures.

 

Well...I ain't scared! Just who is going to figure out my leak!

I am going to buy a new valve...and take off my exisiting one and see if I compare to find any damage to the sealing surface. I hate just throwing out 400 bucks...but I don't want the truck to be down the whole time I ponder...

It seemed that the opinion "used" to be the valve did not "meter" at all. It stayed shut till some abnormal pressure spike blew it open and then it may or may not work poperly again. But...logic would make it seem that due to the volitile nature of the fuel pressures in the rail...that some flow past the valve would allow for a more constant control of fuel pressure.

 

"It seemed that the opinion "used" to be the valve did not "meter" at all. It stayed shut till some abnormal pressure spike blew it open and then it may or may not work poperly again."

It is supposed to stay shut until some abnormal pressure blows it open and it is then supposed to close and stay shut until it again sees some abnormal pressure.

"But...logic would make it seem that due to the volitile nature of the fuel pressures in the rail...that some flow past the valve would allow for a more constant control of fuel pressure."

The valve does not function that way. The Cummins spec is for a very very minimal amount of bypass flow relative to how much fuel is actually being used by the engine. If the valve was actually a flow control device, the test spec for it would be a range of flow at a set pressure ie XXX to YYY ml/minute at ZZZ PSI. The spec is zero to a very small amount of leakage.

 

You had it right. It doesn't "meter", not in the least little bit. Unfortunately, my comments were misunderstood and it was argued several times that it was not a metering device when I never said it was or even eluded to that suggestion. The "metering" references that were made may have thrown you off in the wrong direction. As stated, the valve will almost always be passing a little fuel. It simply weeps at high pressure by design. The valve is just metal on metal inside. As you can imagine, metal on metal doesn't seal perfectly. You put 26,000 psi behind it and the spring starts to flex and it will weep some fuel. That is why you measure it when you test the valve at max psi to see if the pass-through is too much or not. That is what tells you whether it is weeping, which is normal, whether it is popped, or just got crooked and stuck open a little. All the answers are in the measuring cup when your done. It is not overly complicated. In fact, it is quite simple.

I have a copy of the service manual on my laptop and I'll try to post a picture and the part number of the tool for you tomorrow (hopefully). Unfortunately, I am working outside of the country and I'm having no luck finding the company name that makes the specialty tools with nothing more than Google to use. I have it in my e-mail at home, just can't get to it. Hopefully I can turn it up, but it sounds like you have already decided to pull and replace it. It would be nice if you could just pull it and run down to a local auto parts store and pick up a new o-ring and slap it back on. I haven't seen it in so long, now I'm second guessing myself and wondering if it wasn't the pressure sensor that has the o-ring on it instead of the relief valve. Now I'm uncertain. Hate it when that happens. I'm pretty sure the nipple on the rail that the valve screws on to has the o-ring, or is it the other way around.

 

Here is what you originally said:

"The dealer's service manual gives the procedures for testing it. You remove the return line from the top of the relief valve and screw in this special fitting. Attach a piece of hose to this fitting and run it into a bucket. Crank the truck. Unplug the pressure sensor causing the rail to go to max, simulating WOT, and measure the amount of fuel that comes out of the hose. You should get XX ML of fuel in so many seconds."

This is wrong on a few counts:

a) if you disconnect the rail sensor the pressure is going to go to whatever the CP3 is capable of producing. That is much more than the pressure at WOT. This pressure will certainly pop the relief valve. That is the relief valves function. To save the rail from over pressure in case the CP3 goes nuts or something else goes wrong.

b) thus the "XXX mL of fuel in so many seconds" is going to be a test of the CP3 to pump fuel at high pressure and NOT a test of the relief valve at all.

c) The reason the scan tool is used versus unplugging the rail sensor is so that the rail pressure is taken to WOT levels and the relief valve is checked for leakage at that pressure, not the maximum pressure the CP3 is capable of producing.

If the test is performed as you described, all otherwise good relief valves will fail if coupled with a decent CP3.

You also said this:

"When you pull that rail pressure sensor, pressure does go to max. The valve will not open unless you:

(A) Have a bad valve. A good stock valve will not pop during the short duration of the test. There are several tests in the service manual for different parts of the fuel system that requires you to unplug the pressure sensor and send rail pressure to max. A good stock valve will be absolutely fine.

(B) The valve has popped once already and reseated itself. It will pop at much lower pressures from that point on, i.e., when using a pressure box."

Both of these statements are WRONG.

Statement a) The CP3 is the only pressure producing device in the system. When one disconnects the rail sensor the CP3 goes to the maximum pressure it is capable of producing, unless the ECM is smart enough to notice the disconnection and set the CP3 pressure to some preset value. In any event, if/when the CP3 does over pressure the rail, it is the relief valves job to OPEN FULLY and flow whatever it needs to to relieve that pressure. If it didn't, the over pressure would bust either the CP3 or the rail itself or the lines attached to it. A "good stock <relief> valve" will OPEN to relieve the pressure when the rail sensor is disconnected. If it didn't have to under these circumstances, then there wouldn't be any use for it.

Statement b) Relief valves don't drop in pressure after they are actuated the first time or many times, unless they are worn out. If they did drop in pressure then the dealer would have to replace the valve in the test procedure you just outlined, ie disconnect the rail sensor and allow the rail pressure to go to the max.

Lest you think that valves cannot seal 26,000 PSI, consider that the injectors themselves have valves that do just that. If they didn't, you'd get fuel delivery into the combustion chamber at random times and the engine would run horrible.

In my mind the best way to check if the rail relief valve is causing a performance issue would be to connect a flow meter into its return path and monitor that flow under actual operating conditions. DC doesn't do that because it requires driving and loading the vehicle to get realistic operating rail pressures. If they command the rail pressure to the maximum operating pressure, their test probably works just as well.

I don't mean to rag on you about this topic, but I do feel that someone needs to discuss what they feel is the correct way to work on these things so that misinformation doesn't start spreading. I've dealt with 3 cases of Internet mis information this week while helping others work on trucks. It is very frustrating.

 

Ok. I wasn't going to indulge in this anymore, but I just can't do it.

There are two very important things you are not taking in to account.

1) Pressure in the rail is regulated by the fuel return valve (or pressure control valve as Bosch calls it) in the CP3. If the rail needs more pressure, the valve closes a little and pressure goes up. If the rail has too much pressure, the valve opens a little more and pressure goes down. Simple. The fuel return valve in the CP3 gets all instruction on what to do from the ECM and is always connected to the ECM (via those two little wires you see going to it). If the ECM looses its signal from the rail pressure sensor, it will not allow the return valve to shut, forcing rail pressure into the stratosphere. For lack of a better term, we will call it fault protection.

2) The CP3 runs off engine speed. The amount of fuel the CP3 is capable of producing directly correlates to the speed at which the engine is turning it. This test is done at idle speed.

So, couple "fault protection" (return valve open) with the fact that the CP3 is not capable of pumping enough fuel at idle to run a lawnmower, together with the fact that what is in the rail is constantly being bled out via the injection cycles, and you have yourself a scenario where the rail pressure will not be no where near what you are thinking. Unfortunately, I have never measured it during that scenario, so I just don't know what that pressure is. If Don M was with us he could post that number. All I can do is speculate that given the failsafe nature of the system, the engineers that gave this to us would never let it self destruct any part of itself under any scenario as long as it was still in control (i.e. without a pressure box fooling it). The relief valve pops at 28,000psi, although we have seen it pop at less with constant high pressures weakening it over time, you are probably safe assuming this scenario will produce much lower pressures than that.

Sealing 26,000 psi is easy to do with metal on metal if that is what needs to be done. With the injectors, that needs to be done and pressure is not working against the needle coming in from the side. The solenoid provides the force to open it when it is time. The relief valve is purely mechanical and pressure is always pushing against the plunger in the direction it moves, trying to make it open. Big difference there bud.

Now, realizing that we are way off topic and I'm spewing all this out and the 05's may be a different animal all together, we should stop bickering in this thread. PM me if you want to discuss it further. I'll be happy to as I get time. I am trying to work here you know!