Extended crank time - GDI fuel system tests?

Zeb Diagnostician California Posted   Latest  
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2015 Ford Expedition EL XL 3.5L (T) 6-spd (6R80)
P00C6 — Fuel Rail Pressure Too Low - Engine Cranking Bank 1
Extended Crank/Start
Check Engine Lignt On

This vehicle came into the shop w/ the check engine light illuminated and extended cranking after sitting overnight complaint. First shift mechanic (we have day & swing) said he could not duplicate the extended cranking - not sure how long the vehicle sat before / during his testing. Scanned and monitored fuel rail pressure. Cycled KOEO and it reached the desired 56psi. I graphed the fuel pressure PID and went to 2psi within 10 minutes. My first thought was in tank fuel pump check valve? Problem is I have zero experience w/ GDI systems. I researched the code and the testing seems to dead end. I did read the fuel system operation operation and it mentioned a fuel line pressure accumulator & a PCM strategy to energize fuel pump relay to charge the system for cold soak issues. Can the high pressure pump cause a bleed down as well? So best testing strategy at this point? Thanks.

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Glenn Owner/Technician
Texas
Glenn
 

If you are losing initial low pump pressure that quick, there is a bleed off. If the low pressure side cannot hold static pressure, it will create a long cranking condition. Do a physical gauge test and make sure it is not the pressure sensor failing, just to be sure. High pressure pumps do leak down due to failed plunger seal and plunger shaft breakage. Check for excess fuel in the oil.

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Zeb Diagnostician
California
Zeb
 

I had limited time to inspect the vehicle but planned to install a mechanical gauge. Was thinking I could isolate the low side (cap) and test for bleed down. All done if it loses pressure time for low pressure pump. If not hi pressure side would be the culprit. As I mentioned zero experience with GDI but have dealt w/ HEUI International diesel fuel systems. When their high side leaks it's a PITA.

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Glenn Owner/Technician
Texas
Glenn
 

Hi Zeb, I know what you mean. I have dealt with 7.3's for years and then came the 6.0. I bullet proofed a lot of the early 6.0 engines and they were great after you get the kinks worked out of them. The 6.2 was short lived when Ford wanted to make their own. The 6.4 was a huge improvement, but they have there issues too.

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Herman Owner/Technician
Ontario
Herman
 

Does it misfire at all when it does finally start??? I believe this car will cycle the low pressure pump when you open the drivers door. Does it??

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Zeb Diagnostician
California
Zeb
 

System operation describes energizing the FP relay 1-2 seconds as soon as the dome light is commanded on. Supposed to combat fuel vapor @ the injection pump. Conditions are several hours of cold soak. When I got the vehicle it had already been started a couple hours past. I don’t know if sitting overnight meets this criteria or not. I’d like to have a mechanical gauge w/ shut-off ready the…

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Jürgen Owner
Mexico
Jürgen
 

When shutting off the engine after a hot soak the rail pressure should rise when watching the pid on the scanner. If it does not an injector may be leaking or the hp-pump.

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Saifullah Diagnostician
Ontario
Saifullah
 

56psi while cranking on a GDI? Sounds low to me.

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Zeb Diagnostician
California
Zeb
 

56psi is KOEO. Pinpoint test wants to see above 45psi. 56psi matches desired & actual. Running is supposed to be over 100psi.

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Saifullah Diagnostician
Ontario
Saifullah
 

KOEO makes sense. I thought you meant KOER

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Glen Owner/Technician
Illinois
Glen
 

KOEO Spec with manual gauge is 62-74 PSI

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Zeb Diagnostician
California
Zeb
 

Shopkey is all over the place, surprise surprise. Under general specifications it lists 51-73psi running. Pinpoint tests above 45psi KOEO, above 100psi KOER. 56psi on the scan tool works for me, dropping off quickly doesn't work.

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Glenn Owner/Technician
Texas
Glenn
 

I have found that All Data is usually a direct copy from manufacturers information (in many brands). Mitchell On Demand is not user friendly in my experience. Shop Key and others seem to be a generic 'anyone's guess' similar to the older Chilton ‘big book’ manuals. I have older Haynes and vehicle specific Chilton manuals to this day that have saved me many times on older vehicles. Printed…

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Zeb Diagnostician
California
Zeb
 

90% of our 3 shops are happy with ShopKey so it here to stay for the moment. We service & repair heavy duty, construction & AG equipment. Our John Deere service information is from Manuals. A JD 6420 general service manual is $400, the electrical & diagnostics will run $800. JD manuals will give you a brain strain trying to find / sort information. Years ago I worked in a shop that…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Zeb, Yes, JD is proprietary with their repair information. I was a service manager for a local dealer for 3 years. I like the older products and even own a … Propane tractor that I use on a daily basis. Has for modern JD equipment, I think they are over rated and definitely over priced. The JD manuals are very expensive, but worth it if you need exact repair information, especially…

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Glen Owner/Technician
Illinois
Glen
 

Zeb, What pinpoint test and step # states 45 PSI KOEO?

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Zeb Diagnostician
California
Zeb
 

ShopKey OEM testing procedures. Pinpoint test HP “Low Pressure fuel system” . HP3 wants greater than 45psi KOER. HP4 “Low Pressure Leak Down Test” calls for pressure greater than 45psi KOEO. Pinpoint test HC calls for 62-74psi running. HC11 has another leakdown test which seems redundant - KOEO minimum 40psi, less than 5 psi leakdown in one minute.

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Glen Owner/Technician
Illinois
Glen
 

Zeb, Are your test results from a mechanical fuel pressure gauge?

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Zeb Diagnostician
California
Zeb
 

No - all done from drivers seat w/ scan tool. This vehicle was a left over from our first shift. I agreed to research the code and do some preliminary testing during my regular Friday workload. During research I found where to hook the mechanical gauge as well as pressure specifications. I did find the pressure dropping really fast on the scan tool. My next step was to install a mechanical gauge…

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Glen Owner/Technician
Illinois
Glen
 

Zeb, According to what I am seeing the above info is incorrect… HP3 is done with a mechanical gauge Ignition Off after priming the system. HC12 is done by commanding the FP on with the scan tool the watching the pressure with a mechanical gauge Ignition On,engine Off… It also depends if the vehicle has a mechanical return less fuel system or electrical return less fuel system. Maybe this will…

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Zeb Diagnostician
California
Zeb
 

Glen S. I attached HP3 from ShopKey. Bullet point # 6 has “engine running”, last sentence asks for psi reading. ShopKey lists MRFS and adds an accumulator to the GDI gas system. I will say I am no fan of ShopKey nor Ford's Pinpoint testing. Ford has always had testing done piece by piece and it easy to lose sight of the big picture.

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Glen Owner/Technician
Illinois
Glen
 

Zeb, Sorry my above test info should be for HP4. This is where i started looking up info since I assumed the P006C is present Also your HP3 does not match the Ford info

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Zeb Diagnostician
California
Zeb Update
   

Was able to install a mechanical fuel pressure gauge this afternoon. Installed on the fuel line leading back to the in-tank fuel pump. Dead headed the pump and the pressure dropped rapidly (keeps dropping but turned off camera to reduce file size) This vehicle is assigned to another tech so I will recommend he replace the in-tank fuel pump. Thanks all. diag​.​net/file/f7850d1c4… ​

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Saifullah Diagnostician
Ontario
Saifullah
 

What if the line is collapsing? Seen this on a 2016 santa fe.

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