Injector return flow test...

[JCobb]

Okay,



So I tried an injector return flow test, at least the way that I thought you were supposed to do it. I am not sure if I did it correctly, but here is how I did it.



I assumed that we are trying to just isolate the injectors so that we are only getting injector return, not cp3 return, etc.



Not having the required miller tools, I used an m12X1. 5X20mm bolt as a plug in the front filter housing banjo bolt location. This is the line that comes off of the top of the rail pressure relief valve and ties into the CP3 return line.



At the rubber hose connection on that same line, I took off the factory rubber hose and made the return line coming off the CP3 run into a catch can. The other end of the line the one I plugged that comes off the rail relief valve, I left the end where the factory rubber hose was just open because my bolt should have plugged it off.



Then I routed the fuel line that comes off the back of the motor/head and returns fuel to the tank into the graduated cylinder (a quart oil container with 'ml' measurements on it).



This was my attempt to isolate it to just the injector return. I think I did isolate it to just injectors.



I then had the truck close to temp, about 140*F and started it, started my timer, ran it for 1 minute, shut off truck, found that it does way less than 180ml, more like 80ml.

I found that if I added the CP3 return to the 80ml injector return, I had about 280ml.



Did I do this right? If I did, then I am assuming that my return flow is within spec, and my injectors are fine.



I did all of this because of a rough start/idle smoke for 5 seconds problem I had been having. Look at this link here...

Bad FCA, Injector, Rail pressure relief? - Page 3 - Dodge Diesel - Diesel Truck Resource Forums

 

[JThacker]

Ingenious thinking, I think you did it right. Let me study it and go look at my truck and I will get back with you, maybe sag will chime in. He is a chrysler technecian. Jay

 

[TCluff]

I Pulled My Inj Out And Had Them Flow Benched, The Returns Were Low On All 6 With One Completely Failed, I Feel This Was The Most Accurate Way To Go About It...

 

[JCobb]

service manual...

Well that is something to check into, but in the chrysler service manual it states that below 180ml was the acceptable amount, it didn't specify a minimum. Now I am more confused, someone please help!

 

[sag2]

Here is the return flow test with photos for clarity. In this photo the 9012 is a banjo bolt that only allows flow through the length of the bolt. In other words, it does have a hole the long direction, but DOES NOT have a hole passing through the diameter. This isolates the combined return from the pump and POV from the return from the head. So the flow from the pump and POV is measured from the 9012, and the head return is measured off the bottom of the filter housing in the next photo.

 

[sag2]

In this photo, the head return is passing around the 9012 in the photo above, and returns to the fuel tank at the fitting below and to the rear of the filter housing. (Without the 9012 installed, the pump, POV, and head returns are all mixed together at the banjo bolt where the 9012 is installed, because the banjo bolt is drilled length wise AND cross drilled. )To measure the head (injector) return you remove the quick disconnect from the fitting and attach a hose to the engine side an insert it into a measuring cup.

 

[sag2]

In this final photo the hose from the 9012 and the hose off the bottom of the filter housing that normally returns to the tank are measured at the same time. The 9012 should have 1000ml or less, and the head (injector) return should be 180ml or less in one minute with the engine idling. In both cases, less is better. A "good" set of injectors will usually return 100ml or less, and a "really good" set less than 80ml. Remember that the head return is not only from internal injector leakage, but also the connector tube to injector connection as well. To properly diagnose the bad injector, you use the cap off tool to cap off one injector at a time and measure the return flow each time. In very general terms, each injector should return about 15 to 20ml, so if your return is 150ml and you cap off one injector and the return drops to 80ml, you just found the leaking injector or tube.

 

[JThacker]

Hey sag, you helped me thru the same test about a year ago, since then I have sent the injectors to a company and had them bench tested and hi flow nozzles installed. Recently I did the return flow test because of some white smoke on start up and my return values were Engine Cold 1. 70 2. 73 3. 75, after getting up to operating temp and the thermostat opened the values were 1. 120 2. 110 3. 115. Is this normal? If not is it more indicative of injector problem or sealing issue with the connecting tubes or copper washer on the injector, I have a new set of connector tubes and washers to install, if need be. Thanks Jay

 

[sag2]

Hey sag, you helped me thru the same test about a year ago, since then I have sent the injectors to a company and had them bench tested and hi flow nozzles installed. Recently I did the return flow test because of some white smoke on start up and my return values were Engine Cold 1. 70 2. 73 3. 75, after getting up to operating temp and the thermostat opened the values were 1. 120 2. 110 3. 115. Is this normal? If not is it more indicative of injector problem or sealing issue with the connecting tubes or copper washer on the injector, I have a new set of connector tubes and washers to install, if need be. Thanks Jay

Not sure what the 1. 70, 2. 70, and 3. 75 represent. Is that 170ml? If you run the test three times without capping off an injector your return volume should be about the same each time.

 

[JThacker]

Those are volumes of three different tests. With engine cold the head return was in the 70 ml. range three times. With the engine at operating temp. the head return was in the 100-120 ml. range. So the increased engine temp resulted in more head return and I was wondering if this is indicative of more of a leak between connecting tube and injector or maybe the sealing copper washer on the injector or more likely intrinsic injector malfunction. If it is possible to discern this. Thanks, Jay

 

[JCobb]

Update...

Hello sag2,



Well I checked my head return tonight according to your recommendations sag2 (which again I am very thankful for), I am getting under 100ml of return. I am guessing its about 80ml or maybe even less.

I am saying this because, my measurement device only shows 100ml increments, but I know that it took another 45 seconds after the 1 minute was up to fill the bottle to the 100ml mark.



Anyhow, can I now rule the injectors out? Or, in other words, can I rule out the fact that they are cracked or sticking open? They may still be dirty, which would be fine, I just don't want to have to replace them (the whole body). I don't mind taking them out and soaking the nozzles or something to clean them, but, hopefully no replacement of the body needed.



The problem I was having was a cold start problem, truck would smoke a little and idle rough for first 5 seconds of startup. I disassembled FCA and POV, and cleaned them the best I could, thought it fixed the problem, but soon as I ran biodiesel again, it came back.



Switched back to straight diesel fuel, same problem, now using FASS pump and 2 micron filter, same problem still. Put in Power Service and MMO, problems gone, but still on the tankful that has those in it.



Anyhow, if I can rule out the injectors, I will start switching out sensors as one of those might be the culprit (my cousin has an 05 identical to my truck). I was thinking of trying FCA first, then pressure relief valve, then rail pressure sensor (that way I can maybe see which one changes anything?).



What do you think? Thanks a ton in advance.

 

[sag2]

With those return numbers you can rule out the injector leaking internally, or a connector tube leak, but the injector could still be leaking at the tip. The Bio is a very good solvent, and any deposits that were in the fuel system are now broken loose.

So the best way to find the leaky injector is to pull back the exhaust manifold and cold start it. Try to slide a piece of sheet metal or cardboard between the head and manifold to divert the flow so you can see it. The smoking cylinder is the bad one. No need to remove the manifold, just slide it back as far as you can. You might have to start it a couple of times to isolate the cylinder(s)

 

[TMoe]

I once read fuel was used to cool injectors so some return is necessary. That sure doesn't sound right if less is better. Anyway, why is less return from pump, pov, etc. , better? Isn't that a measure of fuel pump output-injector leakage-fuel consumed? This fuel is used to cool the injection pump and I would think the more returned the better for both cooling and filtering. Just curious.

 

[JCobb]

okay...

So sag2,



If I find that by doing this, a cylinder(s) has a leaking injector at the tip, what would my next step be? Clean them, or do I need new tips/nozzles?



Next question is, what if I cannot get it to smoke/idle rough? Seems like whenever I put in that power service, it never wants to do it at startup, but soon as I get it all diluted out of the tank, it gives me some trouble.



I forgot to mention this, but as of late, I have noticed some of what I would describe as a light surging, as in my rail pressure gauge is showing a 4000 psi up and down, up and down,etc. with steady throttle pressure. I can feel it a little seat of the pants, as in truck has all power, then for a second, it has less power, then it has it all back again, then drops off for a sec, etc. Kind of like miss. Truck only seems to do this when cold. Thanks again.

 

[sag2]

I once read fuel was used to cool injectors so some return is necessary. That sure doesn't sound right if less is better. Anyway, why is less return from pump, pov, etc. , better? Isn't that a measure of fuel pump output-injector leakage-fuel consumed? This fuel is used to cool the injection pump and I would think the more returned the better for both cooling and filtering. Just curious.

Your confusing head or injector return with pump return. The pump return is the less than 1000ml spec, and is measured off the 9012. The 9012 splits the two returns for diagnosis purposes.

 

[sag2]

So sag2,



If I find that by doing this, a cylinder(s) has a leaking injector at the tip, what would my next step be? Clean them, or do I need new tips/nozzles?



Next question is, what if I cannot get it to smoke/idle rough? Seems like whenever I put in that power service, it never wants to do it at startup, but soon as I get it all diluted out of the tank, it gives me some trouble.



I forgot to mention this, but as of late, I have noticed some of what I would describe as a light surging, as in my rail pressure gauge is showing a 4000 psi up and down, up and down,etc. with steady throttle pressure. I can feel it a little seat of the pants, as in truck has all power, then for a second, it has less power, then it has it all back again, then drops off for a sec, etc. Kind of like miss. Truck only seems to do this when cold. Thanks again.

You can try to clean the tips but I would leave that to the pro's. You could try solvent and a soft brush at the least, but most likely the deposit is insode the injector tip. You be the jusge if you want to pull the tip and clean it.

As for the rail pressure not holding fairly steady, that is usually the FCA. If it is bad or sticky the idle will sound like it is surging, but the RPM will stay at 750.

 

[JCobb]

thanks...

Thanks for all the help, I tried the exhaust manifold trick, and all the cylinders seemed to smoke for a couple seconds then cleared right up. I isolated them the best I could, and they all seemed to smoke then clear up the exact same way. The truck lately has been running great. I am going to keep monitoring the situation, but if it gives me trouble again, I am going to take the injectors out, and take the tips off soak and clean them. Thanks alot!

 

[Kirwin]

Some further questions for you sag2

I am trying to diagnose a similair problem on my 03 3500 with 49K miles in my signature below. I just returned from a 6300 mile trip out west pulling our TT with a 21K GCW. The truck pulled great. About halfway through the trip I noticed at first what I thought was a miss at idle along with a "rod knock" type sound though not as loud but definetly distinguishable. This sound, almost, a clak clak type noise, can be made very apparent by letting out the clutch to put the engine under load at <1200 RPM such as during clutch engagement. The noise goes away or is masked by other noise at higher engine speeds and seems to be boost dependent. I also noticed what I would call a engine miss only detectable at low engine speeds which results in the truck shaking to some degree at idle. These two things occur with the engine hot or cold but not all the time and seeminly in varying degrees. I have two codes P0633 and P0336. On the trip I pulled two passes on I-70 in the rocky mountains at 53 MPH so I don't think power is down but the engine has much more vibraton to it at low speeds that I can't attribute to anything other than the miss that seems to be present sometimes. I was looking at the injector TSB to try to eliminate the injectors but am now thinking maybe FCA. Do you have any input on this problem? Did I miss something that I should check? Thanks for your time. Ken Irwin

 

[Johnstra]

Kirwin - Yours is almost definitely a bad injector. I had the same problem. Go to your dealer have them use their tool to kill one injector at a time. Set your park brake and ease out in 1st or 2nd. When you get the right injector the knock will go away.

-john

 

[_Hyde]

Isn't there a tool to plug one injector off at a time? I found a web site that had something like that and the tool for the injector return flow test. Now I can't find any of that to save my life. Seems like it was a performance oriented site that had them.

Thanks