I have a 2006 s40 that quit pumping fuel a few years ago. I dropped the fuse box on the passenger side and checked the fuse. I then found a post on the web that said the pump relay was also in that cluster. I pushed on the relays and got it started. Not sure that wiggling the contacts in that fuse box was the fix though. The problem reoccured and I let the car sit for 2 years. My daughter would now like to drive it. I also had problems with the sun roof drains a few years back and the floors flooded quite a few times. I removed all of the carpeting and cleaned it. It is still out, there is a wiring harness on the passenger floor that doesn't seem to have any connectors that could be corroded from the water. Does anyone have a wiring diagram for the car or know what to trace to see where the break is for the fuel pump?
Thanks
Gary

 

That ought to help a bit - there really isn't much to troubleshoot. I'd check to see that the relay has power on the supply side of the "switch", and that it's getting power to the coil when you turn on the key. If not, then you have to trace backward to find out why (in either scenario). It wouldn't hurt to make really sure that the ground connections (that you can get to, anyway) are still OK - one of them failing is just as bad as a "power lead" failing.

 

Thanks for the diagram, I really appreciate it. I have two questions. Where is the relay physically located and does the ecm supply power conditionally to the relay?

 

The relay is R15 in the glovebox fusebox.

The ECM turns on the relay by applying 12 volts to the relay pin 2. So that would be your first check (though listening for the relay clicking would tell you the same thing). Then it's just a matter of testing whether power is available on the "input" pin 5, and (when the relay is turned on) "output" pin 3.

 

Perfect, there are quite a few noises when you turn the key. The pump is not one of them currently. I'll put a stethoscope against the relay although since the ecm powers it I am betting on no power. There is a red triangle on the dash. When I rebuilt the car I used 3 ohm resistors on place of some airbags and once in a while it would complain. Sometimes the keyfob would unlock the passenger side but not the driver side so I'd have to unlock the driver side with the passenger door button. It would eventually straighten out. My point is I grew to ignore the oddball electrical problems because only the dealer with software and an interface could look at any messages or program in new parts like the steering column which had popped when it was wrecked. I don't know if disconnecting the battery will clear the ecm, I will try it first and then check the grounds I can see and report back. Thank you for all of your help.

 

if you pull out the relay, you should see four spades - the two larger ones are for the power to the pump, the two smaller ones are to energize the relay. for testing you can jumper the two large spades to see if it engages the pump. For a first step you can check which spades have voltage with/without the key in the on position and check if the others are ground.

 

I could feel the relay closing when I turned the key so I removed the relay and got 12+ on terminal 5. When I jump it to terminal 3 there is a slight arc but I do not hear the fuel pump running. Terminal 3 has a 3k ohm to ground resistance which seems high for an electric motor. Depending on connections between the fuse box and the pump something could be corroded. However I had this car stored at a building where I had to evict a *#$_% tenant. He had ripped the fuel door off and dumped water in the tank. I unscrewed the valve at the end of the fuel rail and attached a clear pvc hose. I cycled the ignition until it started pumping gas. I'm guessing that water was still mixed in with the gas although the car started running normally. Thatwwas two years ago before I stored it. Is there an access plate to get at the pump or is it like most cars? If so I need to pull it out of this barn and get it on a cement floor before I get underneath it. Thanks for your help.

 

Ouch. Yeah, I'd say that the fuel pump is a goner. If you can bypass the relay (or hear it click, which will almost always mean that it's passing voltage if there is voltage on pin 5), AND you don't hear the fuel pump, then it's going to be either a bad fuel pump (98%) or a bad connection (2%). I just made up those numbers, BTW... But given that there was water in the tank, it's a near certainty that the fuel pump has failed - 3k ohm is a whole lot for a 12V DC motor, as you said.

 

Can you tell me how to get at the fuel pump? I read a post about an earlier year Volvo that had an access panel.

 

I didn't go through this but it looks like it'll have all the info you need...

V50 S40 fuel pump replacement thread