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T6 cranking, not starting.

A mid-size luxury crossover SUV, the Volvo XC90 made its debut in 2002 at the Detroit Motor Show. Recognized for its safety, practicality, and comfort, the XC90 is a popular vehicle around the world. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America). P2 platform.
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MarkCXC90
Posts: 9
Joined: 27 April 2021
Year and Model: 2004 XC90 T6
Location: Leicester

T6 cranking, not starting.

Post by MarkCXC90 »

Hi.

I had a 2003 T6 that started perfectly every time. It now doesn't. :?
Works carried out in between these states. New CV boots and drive shaft at the front. Few new suspension bushed at the rear. I also had to jet wash the underside as it was caked in fine sandy mud to see what suspension bushed needed attention.

The car now happy cranks but doesn't ever catch. It temporarily starts when squirted with Easy-Start so I am assuming this is a fuel issue. I don't get any codes on my generic OBD reader. Mobile mechanic has had a look and poked around for an hour, he also couldn't get any codes and suggested it could be a faulty crank sensor not allowing the fuel pump to pump, the sensor has now been replaced with no change.

Tried the Shrader valves near the fuel filter and on the fuel rail and neither had fuel or any pressure in them.

Any ideas?

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SuperHerman
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Post by SuperHerman »

Fuel pump. Sit in back seat with ear to the middle area cushion. Have someone put key in and turn to position two, but don't start. You should hear the pump prime. If you don't failed fuel pumps are common enough at this age.

MarkCXC90
Posts: 9
Joined: 27 April 2021
Year and Model: 2004 XC90 T6
Location: Leicester

Post by MarkCXC90 »

Hi, thanks for your answer.

Can't hear anything from the pump. I even took the middle row of seats out to make sure. Is there anything that would stop the pump from priming apart from a faulty pump? I've swapped out the cam sensor as well now. Didn't make any difference.

Cheers.

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ggleavitt
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Post by ggleavitt »

This is a 2003 so electrical is a bit different than the post -05 models. No DECOS pump I believe (which means no FPS or PEM). Anyone validate that this correct? It's a UK model as well, not at all sure when International goes DECOS (wold be interesting to know).

Check fuse 25 on the side of the dash (under plastic panel) for the pump. As well, this model year CEM has relays so you could check CMI12 (see viewtopic.php?t=71741 for location) to see if it's broken.

I may find more as I look around but this should get you started.

edit- DECOS information
2006 V8 Ocean Race #740/800 200k, 2008 V8 Sport 183k

MarkCXC90
Posts: 9
Joined: 27 April 2021
Year and Model: 2004 XC90 T6
Location: Leicester

Post by MarkCXC90 »

Hi, thanks for the reply. I can confirm I don't have a PEM as I spent ages looking for it! :D

I don't have a fuse 24 on the side of the dash. I have this on the right hand drivers side:

Image

Image

Nothing fuel related. The left passenger side is a sea of emptiness.

Image

I do have a fuse box in the engine bay. Have I have checked the 15A fuel pump one and it is fine.

Image

Image

Cheers.

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SuperHerman
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Post by SuperHerman »

Gain access to the fuel pump and check that it is getting power. If it is getting power and not turning on - then that is your problem.

You have checked the fuses. I suppose you can figure out the wiring, positive and negative, and send power directly to the pump to see if it works.

MarkCXC90
Posts: 9
Joined: 27 April 2021
Year and Model: 2004 XC90 T6
Location: Leicester

Post by MarkCXC90 »

Hi, sorry for the late reply, sometime life takes over. Anyway, some progress, not much, but some hopefully. Managed to do some tests.

Checking the voltages to the fuel pump.

With the connector NOT plugged in:
Keys not in ignition 11.7v
Keys to position 2 11.4v

With the connector plugged in:
Keys not in ignition 0v
Keys to position 2 0v

I also applied 12v directly to the pump from the battery and I could hear it working. After leaving it working for 5 seconds I attempted to start the car and it started first time, and ran for a few seconds until the fuel ran out.

So.... The pump is working, everything in the engine seems to be working as it started. For some reason the car doesn't want to tell the fuel pump to work.

Any ideas?

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volvolugnut
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Post by volvolugnut »

Check for some wiring connection that you sprayed while pressure washing.
volvolugnut
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MarkCXC90
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Joined: 27 April 2021
Year and Model: 2004 XC90 T6
Location: Leicester

Post by MarkCXC90 »

Bit more of an update. After reading https://www.matthewsvolvosite.com/forum ... hp?t=87867 I wired up the fuel pump directly to 12V and it started and ran fine. Unfortunately unlike the link it stopped running as soon as I disconnected the 12V or connected it back to the proper feed.

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Post by abscate »

This platform doesn’t use a traditional,fuel pump relay wired to the battery.

A hard soldered relay in the CEM sends voltage to the PEM, which then modulates current to the fuel pump as demanded by feedback from the fuel pressure sensor.

The PEM is the most common weak link, you either use an oscilloscope to diagnose the waveforms or buy a used unit to swap in

CEM is central electronics module
PEM is pump,electronics module
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