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Long Cranking, low fuel pressure = check valve?

Help, Advice, Owners' Discussion and DIY Tutorials for the groundbreaking new Volvo S60 2011+, V60 2015+ XC60 2010-2018.
ncnmra
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Long Cranking, low fuel pressure = check valve?

Post by ncnmra » Thu Feb 13, 2020 8:39 am

I have a 2012 XC60 R-Design. This winter it started consistently doing a "long crank" in the mornings. After doing a bunch of research, I'm pretty sure that there is an issue with the fuel pump check valve. Once it starts, it runs perfect, with normal power, etc. As soon as it starts, I can restart no problem within a number of minutes.

I have a ODBII reader and can read the fuel pressure at about 420kpa when it is running. As soon as it stops, the pressure drops to about 190kpa and continues dropping. This morning when I went to start, the pressure was "0". As soon as I started cranking, the pressure rose back to 420kpa, it took a few seconds to crank, and then it fired up, repeating the cycle.

I understand that the fuel check valve is built into the fuel pump which is located in the fuel tank which is idiotically inaccessible save for either cutting out part of the car, or dropping the tank which involves removing exhaust and driveshaft components, so I'm not interested in replacing the fuel pump. However, I understand that some people have installed external check valves. Is there any guidance as to WHERE to install the check valve, and what kind/size is required?

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RickHaleParker
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Re: Long Cranking, low fuel pressure = check valve?

Post by RickHaleParker » Thu Feb 13, 2020 9:07 am

Have you eliminated leaking injectors and leaks in the fuel line?
--------
Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
Platform P2 2004 S60R, B2524T4, AW50/51 AWD, B8444S TF80 AWD, Bosch Motronic 7.0, BorgWarner K24 turbocharger. V8 conversion in progress.

ncnmra
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Re: Long Cranking, low fuel pressure = check valve?

Post by ncnmra » Sun Feb 16, 2020 11:07 am

RickHaleParker wrote:
Thu Feb 13, 2020 9:07 am
Have you eliminated leaking injectors and leaks in the fuel line?
No, I haven't fully. I ran some good injector cleaner through the tank and its still doing it. Wouldn't a leak be evidenced by a smell or visible sign? What is the best method to diagnose a leaking injector? From the looks of it, they aren't cheap, so replacing them pre-emptively sounds like an expensive proposition.

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Re: Long Cranking, low fuel pressure = check valve?

Post by RickHaleParker » Sun Feb 16, 2020 3:54 pm

ncnmra wrote:
Sun Feb 16, 2020 11:07 am
No, I haven't fully. I ran some good injector cleaner through the tank and its still doing it. Wouldn't a leak be evidenced by a smell or visible sign? What is the best method to diagnose a leaking injector? From the looks of it, they aren't cheap, so replacing them pre-emptively sounds like an expensive proposition.
To check for leaking injectors.
1. Pull fuel rail and injectors.
2. Put a small bottle over the end of each injector.
3. Turn key to on but not crank, to get the pressure in the fuel rail up to operating pressure.
4. Turn key off and let it set for hours.
If any of the injectors are leaking, you will see the fuel collect in the bottle.

You may need to fabricate an extension for the fuel line.

Before you put it all back together. Have somebody crank the engine as you watch the injectors spray. The fuel should come out as a fine mist (atomized).
--------
Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
Platform P2 2004 S60R, B2524T4, AW50/51 AWD, B8444S TF80 AWD, Bosch Motronic 7.0, BorgWarner K24 turbocharger. V8 conversion in progress.

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Re: Long Cranking, low fuel pressure = check valve?

Post by jimmy57 » Sun Feb 16, 2020 6:37 pm

On that car there i no way to do the injector leak test. The fuel line is a hard line with no way to have injectors out of ports and fuel line still connected. But you don't need to test for leaking injectors that way. Leaking injectors give black smoke on start and almost always will do this after 15 min or longer shut down and then start within 1.5 hours. If it restarts fine after trips into the grocery etc but has long crank cold then fuel line draining due to check valve is more likely. On that late models (1999 and later for most models) the fuel system is dead end and for the air to get out the injectors have to cycle to vent it. If you cycle the key on twice and then go depress fuel test port schrader valve and let air out and then a little fuel passes and then you cycle key once more and it cranks immediately then the check valve is the issue.

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Re: Long Cranking, low fuel pressure = check valve?

Post by ncnmra » Mon Feb 24, 2020 1:01 pm

jimmy57 wrote:
Sun Feb 16, 2020 6:37 pm
On that car there i no way to do the injector leak test. The fuel line is a hard line with no way to have injectors out of ports and fuel line still connected. But you don't need to test for leaking injectors that way. Leaking injectors give black smoke on start and almost always will do this after 15 min or longer shut down and then start within 1.5 hours. If it restarts fine after trips into the grocery etc but has long crank cold then fuel line draining due to check valve is more likely. On that late models (1999 and later for most models) the fuel system is dead end and for the air to get out the injectors have to cycle to vent it. If you cycle the key on twice and then go depress fuel test port schrader valve and let air out and then a little fuel passes and then you cycle key once more and it cranks immediately then the check valve is the issue.
Thanks for this info. Sadly, there doesn't appear to be a schrader valve on the fuel rail on these vehicles. How do you test the fuel pressure without relying on the fuel pressure sensor if there is no valve??

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Re: Long Cranking, low fuel pressure = check valve?

Post by RickHaleParker » Mon Feb 24, 2020 1:42 pm

ncnmra wrote:
Mon Feb 24, 2020 1:01 pm
there doesn't appear to be a schrader valve on the fuel rail on these vehicles.
Unscrew the Valve cap on the end of the fuel rail.
2020-02-24.png
--------
Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
Platform P2 2004 S60R, B2524T4, AW50/51 AWD, B8444S TF80 AWD, Bosch Motronic 7.0, BorgWarner K24 turbocharger. V8 conversion in progress.

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