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Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Paul Howd on April 22, 2016, 12:23 pm

Year of Manufacture *: GV04 GOE
Engine Size and Code *: 2.5 B5254T4

I am getting a poor supply to the fuel pump.

11.5 volt open circuit, but drops to zero when connected to a load

I am (going on the wire colours) assuming that the relevant wiring diagram on autodata is the first of the three wiring diagrams (Up to 2003, despite it being an 04 reg)

Can anybody tell be where the fuel pump control module (A107) is located?

I have already tried swapping the relay K20

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on April 26, 2016, 10:45 pm, in reply to "Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"
Paul Howd

Well, I have located said module

(Being an electronic box, obviously the best place for Volvo to locate it is on the underside of the car next to the wheel arch (just behind the fuel filter)! Once I had established that this was the weak link in the electrical system I popped the top off and had a look inside. It was full of water ingress corrosion! (Where is the Smiley for "I cannot understand WTF they were thinking?" :/ )

I bypassed it and the car is now running.

A new module is about £300!

What is the purpose of this ECU?

The main ECU controls the relay and the safety related cut out if the engine is not running seems to be operate just fine.

WHY is there an additional ECU here that doesn't actually seem to do anything useful? What is its purpose?

(Appart from providing a future weak link)

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Ian Baxter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1560' width='330' height='300' border=0 style='border:none;'> on April 27, 2016, 7:44 am, in reply to "Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"
Ian Baxter

Hello Paul,
Only a guess

But could it be an ecm to control PWM and fuel pressure.

Ian.

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Paul Howd <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5151' width='330' height='300' border=0 style='border:none;'> on April 29, 2016, 6:04 pm, in reply to "Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"
Paul Howd

I don't think so, the fuel rail seems to have the conventional supply/return and fuel pressure regulator set up.

There is a lot of electronics in this box!

Lots of chips, so it is more than a simple "relay" (And in any case, there is already a conventional PCM controlled relay)

There is a supply, earth, and (I guess) duplex can line.

There is also a supply/earth output feeding the pump.

The car seems to work just fine with the box removed and the relevant power feeds/earths bridged.

Even Volvo do not really seem to know exactly what its purpose is.

(My local Volvo dealer has always been very helpful with technical enquires, as are the other main dealerships that I deal with. So thank you if you are looking

)

So I am still wondering.

Regards,

Paul

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Alan Lange <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3293' width='330' height='300' border=0 style='border:none;'> on April 30, 2016, 9:19 pm, in reply to "Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"

Hello Paul, I've found this rather basic explanation.

Link: http://www.justanswer.com/volvo/9lsra-volvo-v70-does-fuel-pump-module-volvo-v70.html

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Paul Howd on May 3, 2016, 8:09 pm, in reply to "Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"
Edited by board administrator May 10, 2016, 12:42 pm

Thank you, still do not see the point given what is already clearly present. Ho Humm.

Part replaced, fault codes cleared all works fine now.

Paul

Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #

Posted by Shaun Dale <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2719' width='330' height='300' border=0 style='border:none;'> on August 16, 2016, 1:47 pm, in reply to "Re: Volvo V70 2.5 B5254T4 2004 - Poor electrical supply to fuel pump #"

My suspicion would be that it runs the pump no faster than necessary to maintain the correct pressure in the fuel rail. As you currently have it the pump is running continuously at full flow with the pressure being regulated by the pressure regulator in the end of the rail (or the fuel supply unit if a single ended rail is fitted). Slowing the pump would reduce wear and tear on the pump and regulator, reduce pump noise and power consumption.
Whether or not your mod will have any noticeable detriment to reliability you will be able to tell us in the fullness of time!
Shaun.

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