Hi all, was wondering if anyone could help me with this issue. Previous mechanic diagnosed bad injectors, 3 of them was leaking on top of the injector. Code was low fuel pressure. I've changed lots of injectors on Cats, John deere and Komatsu. I replaced the injectors new quills and new injector lines. Changed filters and changed oil at the same time. Primed the system, tried to start and no start. Hooked up ET and says low rail pressure when cranking. Tested PRV and even cleaned it, tested fuel pump and transfer pump. Only 760psi in the rail and needs to be 6000. My customer didn't want to pay for CAT ones, purchased reman from local shop. Never had issues with Common rail system but this is stumping me. Any help would be appreciated. Thank you
Could you start with a Serial Number please. Hours on machine/engine.? Is the HP injection pump original.?
Last 8 FJH00634. 14540hrs. And yes, original HP pump. Forgot to mention, the one way check valve on the PRV for the cooling of the injectors, when I was cleaning it, brake clean spray can open the one way. It's doing it's job, not allowing fluid one way but really easy to open the other. I know that it's just a return line but should it be that easy to open?
Did you install the injectors correctly according to the instructions? This Common Rail system on C9.3 engines is very demanding on the correct installation of injectors. And even after correct installation, you have to start the first time using ether or gasoline in the intake manifold. Also, if you have a TIER 4 engine, you definitely need to install new trim files.
Are you referring to the pressure relief valve #4 at the end of the fuel rail.?
No, the PRV is connected to the rail pressure relief. It's also connected to the drain for the injectors.This is a 336E. Also was wondering, the old injectors had 3 orings where these new ones have 2. Was wondering if that's a issue.
Really, ether? Interesting. I talked to some of my buddies and they suggested plugging off the relief at the end of the rail, go to ET and engage injector disable, then monitor rail pressure on ET and see if it rises. Then I would replace the relief. If not, plug off each injector, crank and see if the pressure rises. Try to eliminate the new injectors that I replaced. They're not new. Customer went to reman and not from CAT
That illustration is the one which appears for the FJH00634 Serial Number you quoted. Do you have any photos prior to installation or are there any Part Numbers marked on the injectors.? Question: Was the engine running before the three injectors were replaced.?
This is the injector with three rings that should be on your engine. It would be interesting to see those injectors with two rings and find out their catalog number. The bottom and middle ring hold the fuel in the return line. And the middle and top ring hold the fuel in the feed line. If there is no top ring and the quills are not pressed tightly, there will be a leak.
These are the injectors that I installed and part number.
Never mind images won't load
Can you post up the injector Part Number.?
Hopefully it went through
It's the same Cat solenoid but the bottom is different. 2 orings instead of 3. I've took this back out to show you guys.
And yes, went through sis procedure. I've replaced injectors before but none with a oring missing but the vendor assured me that this will work. Aftermarket injectors. Don't want to say the vendors name because they helped me before and the injectors that I bought thu them worked.
I just noticed that on the bottom part of my injectors doesn't have a return hole but there's a hole on top of the port that the quills go in. I guess you're right with the quills and return in one section instead of the center orings splitting them. I torqued the quills to spec and the hold down bolts too.
Another thing that I've noticed is that there's a channel for the return hole, looks like it has to return through the quill port.
And only 1 port where as the Cat one has 4. Maybe I should return these. Doesn't look like the same. What do you guys think . Customer is already pissed
If they do not appear to be identical to what was removed (which I assume were OEM) then speaking personally I would send them back whatever the supplier said or what assurances they gave. I'm not against aftermarket parts but the simple fact of 2 o-rings vs 3 plus the difference in ports would both raise red flags for me.
Ok thank you . We'll see if they will return them. If they don't, I guess I'll tell everyone who not to go to. I don't like bringing someone or a company down.
The catalog number of the injector is very poorly visible, but the last digits ***-*645 show that the injector number does not match the one that should be on your engine. You should have injectors No. 456-3493. And of course, the design difference is clearly visible, there is no central sealing ring. In this case, your fuel return line will be connected to other cavities, as a result of which there will not be the required pressure.
I assume that in your photo is the 328-9645 injector. This injector has exactly two sealing rings. And this injector is installed only on the truck Engine C7_C7S.
Curious what the manufacturer/remanufacturer name was on the boxes the injectors came in.
Update, got the right injectors, installed but still have low rail pressure when cranking code. This is on SIS status, I'm only getting 462psi max on the fuel rail. I've changed the PRV, and fuel rail sensor. Any thoughts. Oh and yes removed the pump to get tested and it's good
Oh yeah, new quills, Injector lines torqued, checked fuel pressures 94psi on a actual gauge, blew back the return to tank and feed lines from tank. Checked the relief valve on the primming pump, bypassed the secondary filters and checked the pressure regulating valve and check valve. Wondering if there's anything else that I can check.
Sorry, also did a solenoid test on the pump and injectors
Also removed return line to bleed the system.
I haven’t had much trouble bleeding these after replacing all 6. I cycle the key and let the electric pump run. I hook up ET and cut out all six injectors manually. I crank the engine for a few seconds with the highest line on the rail cracked loose. I tighten the cracked line, power all injectors and it should fire up in a few seconds of cranking.
Ok, I'll try that. I just go with whatever SIS troubleshoot procedures say. It actually says to remove the back to tank line, put a clear tube on it and put in a container. I did that and no air and still no start. What ever happened to Crack three injector lines and crank. I miss old school. Thanks again.
The first start after replacing the injectors can be difficult, there is air somewhere. I recommend starting the first time with a small portion of ether or gasoline in the intake manifold through the air filter compartment.
I've tried the ether, no start, hoping that there's too much air in the system. Thanks for the suggestion.
I dunno about anyone else but IMHO if it won't at least offer to start with a squirt of ether down the intake then it would appear to me that there could be another problem apart from the fuel system. A diesel engine should run, albeit badly, if you keep squirting ether into it. I'd be interested to hear the opinions of others. Do you have ET.? What Active Diagnostic Codes is it showing.?
Low rail pressure when cranking
Im taking advice from the one guy that said to cutout the injectors crack the highest line, reactivate the injectors and crank. Fuel rail pressure is still at 450psi.
I've mostly did all the test for low rail pressure when cranking and still no start. The final test is to do a "Fuel system Functional test" and you need to start it. *** it doesn't start
I even plugged all the lines on the rail except for 1 and still 450psi. Special plugs. $1000 for 5. Wowo
And yes checked the primming pump and it's at 95psi
Quite recently there was a similar problem on an industrial C9.3, after installing fuel injectors there was no pressure in the rail. The problem was that the customer installed the injectors himself without using the service manual for their installation. As a result, reinstalling the injectors according to the service manual led to an increase in pressure in the rail, and the engine began to start.
What I can’t understand is why the engine makes no attempt to fire when ether is sprayed into the intake. Even if it doesn’t run it should at least offer to run.
I used SIS procedures. Im a Red Seal mechanic and have changed many injectors. I've been a contract mechanic since 2013. This is a first for me. Recently replaced a head on a 9.0 John deere and changed the injectors and quills. The customer didn't want to pay for the injector lines but it started first turn. Another mechanic diagnosed that it was bad injectors. He even showed me that the fuel was coming out of the top of the solenoid. So yes the injectors needed to be replaced.
When ether is sprayed it wants to run but dies
Maybe the problem is in the electrics? The fuel rail sensor, for example, is faulty. Perhaps the Shutdown Switch is on?
So it will run off either? Was it running when you disassembled it to change injectors?
I have questions: 1- did you go back in with the right part number of CAT injectors? 2- Who tested the HP pump and is it timed correctly? 3- What is active on the status flag at the bottom left of ET? 4- Have you tried blocking all the lines off and dead heading the HP pump while cranking?
1- yes got the right injectors 2- sorry replaced the pump and yes it's timed right. I got the timing pin and turning tool 3- no active codes but when I crank it the "low rail pressure when cranking " code comes out 4- I did the procedure that to block off 5 injectors and have number 3 go into a container and still 450psi 5- yes I thought of disconnecting the solenoids on top of the pump to put it at full but pressure goes to 0 and solenoid codes comes up
Won't run. It trys to run, but dies. Yes, about 5 months ago it ran. The previous mechanic diagnosed it and left. Was wondering if dye would have effected anything. He put dye in the fuel system, found the problem then here it stayed for 5 months.
Replaced the fuel rail sensor and pressure relief valve. I also thought of the shutdown switch but it works. As soon as you activate it, a code comes on the screen
There’s really too many unanswered questions here. Saying it’s got the right injectors doesn’t tell me what the cat part numbers are, a new HP pump doesn’t tell me if it’s a Cat or aftermarket. And have you done the injector leak off test again after the new injectors were installed? At the end of the day, you’re either not making any flow, or you’re losing all of it. Have to determine which is happening.
Was wondering if anyone knows this but the one line above the transfer pump that goes into the block then two lines goes to the egr i think. Is there a check valve or relief valve in there that might be stuck? I'll get pics
It's the right part number for the injectors and pump. Got it though finning. Will do another leak down test but was talking to my buddy who's a retired mechanic and he said that when I plugged off the rail and had the number 3 into a container, I've already eliminated the injectors. It's still making 450psi. Was wondering if I'm missing a check valve or relief that I've missed.
Here's the pictures
It looks like a return. Sis doesn't say anything about it
I agree capping off the injectors would eliminate them, which brings me back to the HP pump. If you’re getting fuel to it, there should be no reason you aren’t getting fuel out of it. Have you disconnected the PRV line and cranked the engine? Can you take a picture of the HP pump?
These are the part numbers
Here's the picture of the pump
Part numbers are all correct per serial number, so that’s confirmed. And you’ve confirmed you’ve got good flow from the low pressure side going into the pump, correct?
I've checked everything before the pump. I've blew back the feed line from tank. Checked primer pump with a gauge, 94 psi. From there i checked to the secondary filters in and out. 94psi and when cranking 100psi. Just for the hell of it, I bypass the secondary filters completely. And blew back return to tank line. Im going crazy HELP!!!!
You’ve checked right where the low pressure fuel goes into the HP pump right?
PRV has been replaced
Great, not what I asked
No not at the pump. I tested from the secondary filters to the pump but not at the pump. Im going to check it but have to get a 90degree. I see your logic, might be a collapsed hose.
When it’s acting like this we have to think on a pretty fine scale.
Damm 94psi
Going into the pump
And 100psi while cranking
Ok, can you block all 6 injectors and see what the rail pressure is?
Are you seeing engine RPM on ET? Would be nice to know what current the solenoids on the HP pump need to see for startup but as far as I know, that information is not publicized for peasants like us.
Have you pulled the supply line from the high pressure pump to the common rail and verified fuel is actually flowing into the rail? I'm not sure if CAT has a spec, but on the Cummins common rail engines they have a flow test from the high pressure pump to a graduated cylinder. If that's in spec it would rule out low pressure system and the high pressure pump. Just food for thought, I had a Cummins QSB for a crank no start, capped all the injectors one at a time. No change to the pressure in the rail. Could not get over 500 psi when cranking. Found the flow test and discovered my pump was not flowing a drop of fuel to the rail. FRP sensor read zero at key on engine off and 500psi when cranking. After the pump replacement I spoke with a Cummins tech and was advised the FRP sensor have a plus or minus of 500 psi at low pressures. Not really sure why it read 500 psi when cranking but the pump Repaired it. I saw you have already replaced the pump but a flow test might help in diag if this is a low pressure issue or high pressure issue. Hope this helps.
This might sound dumb but is it possible one of the supply hoses has failed internally and made a flap in there and is shutting fuel off to high pressure pump? I remember if rail pressure is below 1400 psi cranking it's not going to light
I checked the supply line to the pump and it's at 94psi when the pump is primming and 100psi when cranking so I think that the lines are ok.
Have to wait for one. I have 5 but the 1 will be here tomorrow. Was thinking of folding one of the old lines and maybe braze the end of it to do this test. I see what you want to see. If the PRV is working.
Yes I’d like to see if the pump is capable of putting out the flow to the rail in the first place. If you still don’t see pressure on the rail, disconnect the PRV line and see if you’re losing it there. There’s only one of two things going on, you’re either not making flow or losing it.
I really appreciate you guys giving me advice. That's why I come on these sites to get a second option. I couldn't wait, I grabbed a old injector line hammered it flat and tried it. Went to 10000psi. And yes, I was monitoring it. So what I did next, I know can be dangerous, I installed, 1 at a time, the injector lines and monitor the psi. I put #1 injector line in and cranked. Went to 7000psi and I stopped. #2 went in and the same until I got to #4 which had no psi. Installed the rest except #4 and she starts. When it was primming #4 was puking out fuel where all the other ones didn't. I guess you can't trust new parts. Thanks everyone for the advice
And ahart , thank you for the advice. If you didn't advice me to plug the rail, I wouldn't have a clue. Thanks for your help
You isolated the system and found your issue. All it takes is one, glad you found it.
Good post. Glad it’s all sorted. Excellent example of asking for help and getting it.
And another example of the statement regarding parts - "New just means it hasn't been tested in service yet".
Well here I have a update. Got the new injector installed it and it's still puking fuel out of the new injector and quill. Today I swapped the #3, which I know works, injector to #4 and #4 still puking out when primming. I plugged off the #4 on the rail and it starts. I put the line back on and no start. I looked down the injector bore and nothing out of the ordinary. What would make the fuel come out of the quill where none of the other ones do that. Only on the #4 cylinder. Hopefully someone has run into this and can help me again.
I was thinking that it might be the sleeve but when I looked down the bore it doesn't go near the passages for the return. The bottom and center orings seal of the return. And the top one is more of a oil seal.
Just for the hell of it, I reconnect the #4 line back on and low rail pressure code comes back on. Could it be a head issue? Maybe?
Is it the same quill tube as before?
Another thing I was thinking of, is the quill tube retaining nut seating down all the way? There really should be no reason for it to leak if the tube is securely fastened to the injector. Maybe something in the thread bore that’s keeping it from tightening all the way?