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05 LLY Crank No Start after CP3 Replacement

18K views 11 replies 4 participants last post by  ABchevy 
#1 · (Edited)
Hey all,

A couple months ago I acquired an 05 lly for cheap because it wasn't running and it was in need of a new CP3 (according to the mechanic at the local dealership). After a long process I got the old pump out and confirmed that the CP3 was bad (the housing had rattled apart, and was for sure sucking air). I got the new one in, and put everything back together. Now i'm in a situation where even after trying to prime and crank multiple times, the truck just won't fire up.

I know I need to take a few readings with my Tech2 before I can really pinpoint the problem (rail pressure, ect). But I'm wondering if someone might have some thoughts, if this has happened to them as well.

Also, one hopefully minor detail. My helper busted the Barometric pressure sensor that sits on the drivers side of the air intake. I have a new one on the way but I put a pressure sensor of a 6.0L gas there in the mean time (same plug, same size, just not interchangable from what I read). I was hoping that wouldn't affect its ability to fire up, but it very well might be. Any thoughts on this too?

Thanks in advance.
 
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#3 ·
Well I got at the truck today again. Bled the air again as much as I could, primed and cranked. No dice.

Bad news keeps coming unfortunately. Used the tech2 and the rail pressure is reading about 5 MPa, which is about half of the 1450psi required to start from what I've read.

Any thoughts?
 
#4 · (Edited)
Used the tech2 and the rail pressure is reading about 5 MPa, which is about half of the 1450psi required to start from what I've read. Any thoughts?
You have the new BARO sensor in yet?

1 MPa (megapascal) is equal to approximately 145, PSI
100 kpa is roughly 14.5 PSI.

High Pressure Common Rail Basic Information

The high pressure pump builds rail pressure and delivers it to the fuel rail manifold where it flows through the injector lines to the injectors. The fuel pressure regulator in the high pressure pump controls rail pressure. The injectors have a hollow check ball that holds high pressure fuel until the fuel solenoid is actuated by the ECM, this allows the check ball to rise off its’ seat and an injection to take place. If the check ball in the injector is leaking due to erosion on the seat or the high pressure limit valve leaks then it will not build enough rail pressure to start the engine. It takes approximately 2500 PSI rail pressure to start.

No Start or Hard Start

1) Excessive fuel restriction, check or change fuel filter.
2) Use a vacuum gauge to check the suction side of the fuel system. You should have no more than 5 inches Hg at WOT (wide open throttle) or 7-8 inches Hg under load. If you still have too much restriction after changing the filter, check for collapsing soft fuel lines by the drivers side valve cover and under the truck near the transmission. The fuel tank pick up may also be plugged. Too little vacuum (less than 2 inches Hg) means that it could be sucking air.
3) Check for air in fuel system, install clears lines before and after the filter housing to check for air in the lines.
4) Confirm actual versus desired rail pressure, even under crank no start conditions
5) If the above are OK, then it comes down the following.
1) fuel injectors (see injectors for more diagnostic information)
2) high pressure injection pump – CP3 pump
3) Fuel pressure regulator, check to make sure it is not stuck.
4) fuel pressure relief valve (high pressure limit valve), check to make sure it is not leaking into the return system when rail pressure is 160 MPa
6) Before condemning the high pressure pump you need to make sure there are no high pressure fuel leaks.
 
#5 ·
No, the new Baro sensor is still on the way. Still not getting any codes either.

I'm going to pull enough apart to take the fuel feed line to the CP3 off and make sure there's no air in there first. If that doesn't help I'll have to start checking the return rates to see which injectors might be causing problems.
 
#6 ·
Well, more bad news today. Got myself a new fuel filter and decided to also install a clear line to the fuel filter inlet. On cranking, it really looks like there's not a whole lot of movement (or none) in that intake line, leading me to believe that the cp3 is either not sucking enough fuel, or something is preventing it from doing so.

I'm going to pull the tank later today and make sure there's nothing restricted inside there, but if that's a pass I'm thinking I have a vacuum leak somewhere, which is odd to me considering I was able to get the primer pretty hard before.
 
#7 ·
I replaced the engine in my truck, had put all the fuel injection on replacement, got ready to start, and would not, rail pressure was never building, watched it on my scan tool. i figured it was a bad cp3 although it ran on prior engine. as I tore it down, I found a almost tight pressure line that had been leaking. I tightened it up and reassembled it, primed up and fired right up. 2 days later, hooked up to camper and went camping, 40 miles out, I was getting a fuel smell and smoke pouring out the back of truck, again, found the pressure sensor that I removed several times in diagnosing, was not fully tight. so 2 ft off the white line on a 65mph hiway, i got that tightened up. all was good after that, had a happy time camping.

moral to this story, double check all pressure lines, with these systems building up to 26,000 psi, a small leak is a bad leak and will cause no start to lots of smoke.
 
#8 ·
moral to this story, double check all pressure lines, with these systems building up to 26,000 psi, a small leak is a bad leak and will cause no start to lots of smoke.
True, I've checked and rechecked everything, so I can say fairly confidently that a leak in the feed side isn't the issue.

However...I did a simple return rate test on the main return line yesterday, and I'm well over spec for how much total fuel should be returned on 15 sec of crank (160ml as opposed to ~100ml). So now I'm looking for the best place to test each individual bank under cranking, and then i'll be testing each injector on the bad bank (or banks) individually.
 
#9 ·
Here's an update on what the basic return flow tests yielded after the full 15 sec crank:

Amount from main return line to the tank: ~150ml
Amount from passenger side bank: ~27ml
Amount from drivers side bank: ~25 ml

So, it looks like there's at least 1 per bank causing an issue. Those are all the tests I have time for this weekend so I'll have to decide whether it's worth the trouble to test the return flow individually, or just remove all the injectors and have them tested at a shop. I'm not pleased with the prospect of throwing more money at the problem, but it looks like I don't have a choice.
 
#10 ·
one other place to check on the fuel filter housing is the plunger, heater plug, purge plug, one of my trucks had a small suction leak on the heater part, so I got all new seals to rebuild entire head unit.



here is a per cylinder flow rate I got with rebuilt injectors


I made up a test kit by getting 8 medical syringes from drug store, they are plunger type that measures up to 10 ml, made a plate of wood to mount them to keep them in order and secure. I then got fish tank clear air hose which fits snugly on tip of syringe, then carefully removed the return lines from injectors and used a set i had as spares to run 8 individual lines. from that point, I filled each one and let them drain to injector to fill the lines, then drained them to the 0 mark, cranked the engine and each will show the return rate. if you have a scan tool or efi live to command the rail pressure to be near 17000, or at least to monitor pressure

one other thing I did was removed all the glow plugs to reduce the compression putting less strain on the starter.





fuel return rates should be no more than 3.7 ML as per gm spec
cyl, run for a minute 15 sec crank bal at 183 deg
1 6ml 4 -2.6
2 5.5 3 -.1
3 5.5 3.5 2.2
4 6 4 -4.1
5 5.5 3 5.6
6 6.5 4 -1.2
7 6 4 -3.3
8 5.5 2.5 4.0


I found this info on a page last year, perhaps some info will help with diagnosis


Fuel Specific Gravity Testing
Use a J 38641-B Diesel Fuel Quality Tester to measure the fuel specific gravity (API Rating). Follow the instructions on the tool to btain the proper temerpature-adjusted value. This information must be accurate for the proper diagnosis of the fuel system.

Fuel Injector Return Flow and Fuel Pressures
The fuel return from the fuel injectors to the tank will vary based on the API value of the fuel. Measure the Fuel API with the Diesel Fuel Quality Tester. For this reason the Fuel System Diagnosis-High Pressure Side values will vary for identifying a fuel injector or fuel pump concern. Use the following tables when referred to by the diagnostic. The first table is to be used during the initial diagnosis to identify the worst fuel injectors. After the fuel injectors that fail the first part of the test are replaced, the return flow from each fuel injector must be measured again. This is because the fuel system is returning less fuel to the tank, and thus the fuel pressure is higher during the retest. Failure to use the correct table may result in the replacement of good fuel injectors.

API Rating = Maximum Single Fuel Injector Return Flow = Maximum Fuel Injector Bank Return Flow
30-34 = 3 ml = 12 ml
35-39 = 4 ml = 16 ml
40-44 = 5 ml = 20 ml

Retesting Fuel Injector Return Flow Values
API Rating = Maximum Single Fuel Injector Return Flow = Maximum Fuel Injector Bank Return Flow = Fuel Pressure at cranking speed (FICM Disabled)
30-34 = 4 ml = 16 ml = 176-180 Mpa
35-39 = 5 ml = 20 ml = 134-178 Mpa
............................... 176-180 Mpa
40-44 = 5 ml = 20 ml = 114-135 Mpa

Test Procedure
The fuel flows through a pre-filter screen in the tank and to the engine through the fuel supply lines. There is no lift pump in the fuel tanks or on the frame. The fuel passes through the base plate of the fuel injector control module (FICM) to cool the module. From the FICM the fuel flows to the fuel filter assembly, which combines a water separator, a prime pump and a filter element. Within the assembly, there is also a fuel heater. An integrated hand pump is used to prime the fuel system after changing the fuel filter or servicing the fuel system. The fuel injection pump at the front of the engine valley includes a fuel supply pump and a high-pressure pump. Fuel is drawn to the supply pump from the primary fuel tank by the supply pump and delivered to the high-pressure pump.
High Pressure System
The much larger section of the pump assembly is the high-pressure fuel injection pump. The pump is engine-driven by the camshaft gear. From the high-pressure pump, the fuel flows through the junction block. The junction block routes pressurized fuel to both common fuel rails. Each common fuel rail supplies one bank of four fuel injectors.
Return System
The Fuel Return System routes fuel from the fuel injectors, the junction block, and the fuel injection pump. The return fuel travels to the fuel cooler and then to the fuel tank. This fuel is used to cool and lubricate the injection pump and the injectors.
Important:
• If you were not referred to this test from another diagnostic, do not perform this procedure.
• Only perform this test when the fuel is more than 18°C (65°F).
• The fuel return volumes vary based on the API rating of the diesel fuel.
• A fuel injector may have high fuel return flow only at higher engine temperatures.


Were you referred here from one of the following diagnostics?
• DTC P1094
• Surges/Chuggles in Symptoms
• Rough, Unstable, or Incorrect Idle in Symptoms
• Fuel Injector Balance Test with Tech 2
- If you answered Yes, go to the Fuel Pressure Regulator Graphing after step 48.
- If you answered No, go to Step 2.
Remove the air duct from the air cleaner assembly and the turbo inlet.
Remove the air intake pipe. Refer to Air Intake Pipe Replacement .
Drain the coolant and remove the water outlet tube. Refer to Water Outlet Tube Replacement in Engine Cooling.
Object Number: 744233 Size: SH
Click here for detailed picture of above image.
Remove the fuel injection pump fuel return rubber hose from the junction block (2). Cap the fitting on the block with a 3/8 inch rubber cap (1) to prevent fuel leakage.
Object Number: 744234 Size: SH
Click here for detailed picture of above image.
Attach a rubber hose (1) with a barbed fitting to the fuel injection pump return hose and insert the other end into a 1 gallon clean fuel container (2).
Remove the ignition 1 relay or EDU relay, as equipped, using the J 43244 Relay Puller Pliers.
Object Number: 660433 Size: SH
Click here for detailed picture of above image.
Remove the glow plug harness bracket bolt.
Remove the glow plug harness bracket nut from the valve cover.
Remove the glow plug controller/relay mounting nuts.
Reposition the glow plug controller/relay.
Object Number: 755230 Size: SH
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Remove the fuel line retainers.
Object Number: 660446 Size: SH
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Remove the banjo bolt (2) from left rear cylinder head.
Object Number: 844173 Size: SH
Click here for detailed picture of above image.
Install the black hose (1) of the J 45873 Fuel Return Volume Test Kit to the left rear cylinder head and install the other end of the hose into one of the J 45873 graduated cylinders.
Object Number: 744233 Size: SH
Click here for detailed picture of above image.
Remove the banjo bolt (3) from the leak-off block.
Object Number: 844176 Size: SH
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Install the other black hose (1) of the J 45873 to the leak-off block (2) and install the other end of the hose into another J 45873 graduated cylinders.
Object Number: 744233 Size: SH
Click here for detailed picture of above image.
Remove the banjo bolt (4) from the junction block (2).
Crank the engine for 15 seconds while observing the fuel pressure relief valve on the junction block for fuel leakage.
• If fuel is leaking from the fuel pressure relief valve, replace the fuel pressure relief valve. Refer to Fuel Pressure Relief Valve Replacement .
• If no fuel is leaking from the fuel pressure relief valve, go to step 19.

Object Number: 850646 Size: SH
Click here for detailed picture of above image.
Crank the engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or both of the J 45873 graduated cylinders (1).
Elevate the hoses (2) to retain the fuel in the hoses, and empty the graduated cylinders into a suitable container.
Install the hoses (2) into 2 of the graduated cylinders (1). Important: The engine cranking speed must be more than 150 RPM.
Crank the engine for 15 seconds.
Measure the quantity of fuel in each of the graduated cylinders. Refer to Fuel System Specifications for fuel return flow specifications.
• If there is more than the specified quantity of fuel from either cylinder bank, remove the valve cover from that bank. Refer to Valve Rocker Arm Cover Replacement - Lower Left Side or Valve Rocker Arm Cover Replacement - Lower Right Side , then go to step 24.
• If there is less than the specified quantity from each cylinder bank, replace the fuel injection pump and repeat steps 19-23.
• If the fuel injection pump has already been replaced in this repair and there is less than the specified quantity of fuel from each bank, go to step 45.

Object Number: 660477 Size: SH
Click here for detailed picture of above image.
Important: When the fuel injector pressure lines are removed, debris will fall into the fuel injector inlet fitting. Vacuum the debris from the inlet fitting of the fuel injector.
Remove the return line from injectors.
Object Number: 847742 Size: SH
Click here for detailed picture of above image.
Install the four yellow hoses (2) from the J 45873 to the injectors (1) and the other end of the hoses into each of the J 45873 graduated cylinders. Notice: Refer to Fastener Notice in the Preface section.
Install the 4 injector supply lines. Tighten
Tighten the supply lines to 44 N·m (32 lb ft).

Object Number: 674653 Size: SH
Click here for detailed picture of above image.
Connect the engine-to-chassis harness connectors to enable the starter.
Object Number: 674616 Size: SH
Click here for detailed picture of above image.
Install the fuel filter hoses, FICM hoses, and the fuel supply hose. Push the fuel supply hose in until it locks.
Install the black hoses from the J 45873 into the container that the fuel injection pump return hose is in. Prime the fuel system 30 times to remove air from the fuel system. Air will be forced out of the system within 2 minutes.
Crank the engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or more of the graduated cylinders.
Elevate the 4 hoses to retain the fuel in the hoses, and empty the 4 graduated cylinders into a suitable container.
Install the hoses in the graduated cylinders in numerical order. Important: The engine cranking speed must be more than 150 RPM.
Crank the engine for 15 seconds. Important: A fuel injector may have high fuel return flow only at higher engine temperatures. If the high return flow ceases between the bank return flow test and the individual injector return flow test the fuel injectors may need to be heated to an operating temperature before performing this test.
Measure the quantity of fuel in each of the graduated cylinders. Refer to Fuel System Specifications for fuel return flow specifications. Remove the fuel feed pipes from any injectors that have high return fuel flow, and install the EN 47589 Fuel Pressure Test Adapter Cap(s) to the fuel rail outlets. Then go to step 35.
Repeat steps 30 through 34 until no fuel injectors have more than the specified quantity of fuel flow.
Were both banks of fuel injectors tested with steps 30 through 35?
• If the answer is YES, go to step 44.
• If the answer is NO, go to step 37.
Ensure that the hoses are still installed as they were in steps 14 through 17.
Prime the fuel system 30 times to remove the air from the fuel system. Air will be forced out of the system within 2 minutes.
Object Number: 850646 Size: SH
Click here for detailed picture of above image.
Crank the engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or both of the J 45873 graduated cylinders (1).
Elevate the hoses (2) to retain the fuel in the hoses, and empty the graduated cylinders into a suitable container.
Install the hoses (2) into 2 of the graduated cylinders (1). Important: The engine cranking speed must be more than 150 RPM.
Crank the engine for 15 seconds.
Measure the quantity of fuel in each of the graduated cylinders. Refer to Fuel System Specifications for fuel return flow specifications. If there is more than the specified quantity of fuel in either of the 2 cylinders, remove the valve cover from that cylinder head. Refer to Valve Rocker Arm Cover Replacement - Lower Left Side or Valve Rocker Arm Cover Replacement - Lower Right Side . Then perform steps 29 through 35 on the bank of fuel injectors with the high fuel flow, Then go to step 44.
If both of the cylinder have less than the specified quantity of fuel, go to step 44.
Replace all of the fuel injectors that had fuel rail outlets capped. Refer to Fuel Injector Replacement .
Install all disconnected and removed components. Refer to the applicable procedures.
Start and idle the engine. You may have to prime the fuel system before the engine will start.
Connect a scan tool.
Command the fuel pressure control to 160 MPa with a scan tool.
• If the fuel pressure is more than 145 MPa, the system is OK.
• If the fuel pressure is unable to increase to more than 145 MPa, replace the fuel injection pump. Refer to Fuel Injection Pump Replacement .

Fuel Pressure Regulator Graphing

Set up the scan tool in the following format:
1.1. Select the Data Display on the scan tool.
1.2. Select Engine Data 1.
1.3. Select the More softkey 2 times.
1.4. Select the Live Plot softkey.
1.5. Select the Engine Speed, Actual Fuel Rail Pressure, and Desired Fuel Rail Pressure parameters by highlighting each parameter and depressing the ENTER softkey.
1.6. Select the Accept softkey.
1.7. Select the More softkey, then select the Change Min/Max softkey.
1.8. Select the More softkey, and adjust the parameters to the following Min/Max ranges:
• The Engine Speed Min/Max range is 0 to 1000 RPM.
• The Actual Fuel Rail Pressure Min/Max range is 1.0 to 160 MPa.
• The Desired Fuel Rail Pressure Min/Max range is 1.0 to 160 MPa.
Start and idle the engine.
Good Fuel Pressure Regulator Graph, 0 Miles

Object Number: 877557 Size: MF
Click here for detailed picture of above image.
(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure
Good Fuel Pressure Regulator Graph, 26K Miles

Object Number: 877556 Size: MF
Click here for detailed picture of above image.
(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure
Fuel Pressure Regulator Graph, Surging

Object Number: 877558 Size: MF
Click here for detailed picture of above image.
(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure
Observe the live plot for sharp changes in the Actual Fuel Rail Pressure above and below the Desired fuel rail pressure while performing one of the following actions:
• Idling the engine.
• Shifting the transmission from Park to Drive, and back to Park.
• Turning the steering wheel from lock to lock.
• Turning the air conditioning ON and OFF.
If there is a violent fluctuation in the Actual Fuel Rail pressure, as seen in the third Graphic above, replace the fuel pressure regulator. Refer to Fuel Pressure Regulator Replacement .
 
#11 ·
more thoughts, check that the fuses and relays are all in good working order. i am remembering back several years now, that I had the #5 ecm relay going bad, the engine would randomly die and with a bump would come back alive. I replaced the relay with the AC relay, and had no more problems, then bought a new relay for AC. since you bought this truck in a non running condition and that you found the pump busted up some, is it possible that the fuel rails and injectors may have been contaminated? difficult part is that you may have never head this truck run prior to purchase, and that is hardest part of diagnostics.

the fuel feed line from tank to filter in my trucks have no check valve, so if you remove the suction line and blow it back, you should get no restriction. unless you have a full tank, then your pushing against that volume of fuel. this will hopefully help you from not removing the tank, possibly easier to remove the bed or unbolt it on driver side, loosen up passenger side to create a hinge and lift the drivers side to gain access to the tank, be sure to support the bed so it does not crush you.

did you check the service port on the suction line to make sure thats not leaking as well?
 
#12 ·
Thanks for the tips so far.

I have checked fuses and relays, as well as rebuilt the filter head system and dropped the tank to check restrictions. There doesn't seem to be any sort of leak in the supply side.

Based on the return test and the volume of fuel in the return system, I'm at the point where injectors are the most likely cause. I'll be looking to test each injector individually this week, and go from there.

I'll also be shimming the FPRV as a precaution (even though no fuel came from the rail I want to be sure it's not causing any additional problems before buying injectors).
 
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