S80 No power to the Fuel Pump Going Crazy

[osiris]

Ok guys so here is my problem.

2004 Volvo S80 2.5T AWD

I've spent more than two days diagnosing my no start problem and found the follwing:
***I can power the fuel pump directly and it runs and the car will start
***There is power to fuel pump fuse
***The fuel pump relay tests good but the fuel pump doesn't cycle on
*** I can jump terminals where the relay plugs in and the fuel pump runs

I have checked all wires and and connections everything seems to work properly. I do have a message saying " alarm system service required" however, the worked fine and ran fine even when this message displayed on the dashboard.

When it started failing, i got out of school started the car but was kinda hesitant at first like it was sputtering for a little bit but then it kicked in normal. I didnt pay much attention to it and drove to the gas station however when i got out of the car at the gas station and tried to lock the car with remote it didnt work. After that I started the car and drove home. Same night, I tried installing a new air bag module due to it being in an accident and when I tried starting the car i got nothing. I put the old air bag module in and NOTHING. Ever since the car hasnt started on its own unless i manually power the fuel pump as I mentioned earlier.

My sunroof wasnt working a couple days before that after leaving the car wash but 30 min later it started working.

Any ideas what this could be? I have spent hours and hours trying to figure it out, I'm going crazy!

[reggit]

Obvious things to me to check?

It your fuse good? Check with a multimeter to ensure continuity - they can look good by eye even when they are bad sometimes.

Check you've got 12v on the input terminals to the relay (obviously this will only be there when the car needs the fuel pump on).

[david philips]

try a light tap on the pump relay, look closely at the relay for loose solder terminals etc, not easy to check %100 with out a replacement relay , good luck.

[Chris_Rogers]

Here's a thought, if the car thinks it's crashed then it will stop the fuel pump to prevent a fire.
This maybe what you're experiencing, have you got a SRS message on the dash as well?

[Clan]

Originally Posted by Chris_Rogers

Here's a thought, if the car thinks it's crashed then it will stop the fuel pump to prevent a fire.
This maybe what you're experiencing, have you got a SRS message on the dash as well?

I think that is the answer , it will need to go to the dealer to have the crash mode reset with VIDA .

[Bernard333]

The fuel being cut off following the air bags going off would seem to be a sensible option but I have a 2001 V70 T5 with two air bags having deployed , the car starts and runs ok . The airbags have not yet been replaced and nothing has been reset in the elctronics system. Could be a different mode of operation in the USA than the UK or even that my car should have shut off the fuel so dont rule this possibility out .

[ShadeTek]

...or your immobiliser has got confused. Try disconnecting the battery for 10 minutes to reset it.

[Wannavaux]

Can I make one last suggestion to you as its what caught me the other week. Have you tried swapping your fuel pump relay with the one for your front fog lights?

I too had no power to the fuel pump, power to the fuse, could hear the relay clicking when ignition switched on but it would not cycle the pump pre start. After convincing myself that the fuel pump had gone (and removing the rear seats in the process to start pulling it all apart, I put 12 volts across the terminals and it was alive.

My fault turned out to the the fuel pump relay. Although it was clicking, it wasn't doing its job, I switched mine with my front fog relay (as they are the same) and my V70 has been completely reliable ever since. I truly hope the same problem resides in yours, new relays from Volvo are about £8.

Fingers crossed for you.

[osiris]

Originally Posted by reggit

Obvious things to me to check?

It your fuse good? Check with a multimeter to ensure continuity - they can look good by eye even when they are bad sometimes.

Check you've got 12v on the input terminals to the relay (obviously this will only be there when the car needs the fuel pump on).

Im going to check this out, I only inspected them and they looked ok.

[osiris]

Originally Posted by david philips

try a light tap on the pump relay, look closely at the relay for loose solder terminals etc, not easy to check %100 with out a replacement relay , good luck.

I took out the relay tapped it a little bit I even opened it up to see if there was anything wrong but it looked ok, I am going to try a different relay and see what it does.