How likely is it that a cable is broken - Fuel pump won't start

Volvo742 · Post by **Volvo742** » 02 Aug 2020, 18:31

Car: Volvo
Model: XC70
Year: 1998

Issue:
Fuel pump won't start when I turning the key to position II or III.

Fault codes:
No fault codes

Have checked:
* Fuel relay 103 clicks
* Fuel pumps have resistance connection when I measure the cables with a DMM

Exceptions:
It can happen that the fuel pump wakes to live and I can start the car. Then it will die later after few seconds.

Cause of the problem:
I have measure between pin 87 and pin 31 at the fuel pump relay(2/23). No sound from my DMM. So I'm expecting a cable break?

Can anyone tell me where the fuel pumps are at this electric wiring diagram below? I have two pumps, one at each side.

Post by **jreed** » 03 Aug 2020, 08:36

If you haven't done it already, it might be a good idea to test the system with a jumper wire between #87 and #15 on the fuel pump relay socket -- that will rule out the fuel pump relay which has a high failure rate.
It looks like you have already read through this excellent summary from cn90:
viewtopic.php?t=52252
The wiring diagram on his post has the fuel pump listed as part 6/31. On the diagram you posted, I don't see an item that looks like the fuel pump.

Volvo742 · Post by **Volvo742** » 04 Aug 2020, 02:28

jreed wrote: ↑03 Aug 2020, 08:36 If you haven't done it already, it might be a good idea to test the system with a jumper wire between #87 and #15 on the fuel pump relay socket -- that will rule out the fuel pump relay which has a high failure rate.
It looks like you have already read through this excellent summary from cn90:
viewtopic.php?t=52252
The wiring diagram on his post has the fuel pump listed as part 6/31. On the diagram you posted, I don't see an item that looks like the fuel pump.

Thanks for the reply.

I have checked with a jumper wire. Did not work. But I have also measure the resistance on these cables in the picture above. They have some kind of resistance.

I unplug the connectors and measure between them.

Post by **abscate** » 04 Aug 2020, 04:18

Go back and look for 12 Volts on the voltage scale at the fuel pump connector

The fuel pump isn’t on that diagram, you need a different one.

Volvo742 · Post by **Volvo742** » 04 Aug 2020, 07:32

abscate wrote: ↑04 Aug 2020, 04:18 Go back and look for 12 Volts on the voltage scale at the fuel pump connector

The fuel pump isn’t on that diagram, you need a different one.

I have two pumps right?

Here i have some more pictures.

Here I measure the resistance:

No voltage between Pink and black cable when key is in position II:

Volvo742 · Post by **Volvo742** » 04 Aug 2020, 07:33

I've tried with different key. No sound from the pump.

Post by **BEJinFbk** » 04 Aug 2020, 08:01

As you are in Sweden, it may be your security system.
Does this car have a chipped key?

Volvo742 · Post by **Volvo742** » 06 Aug 2020, 17:48

BEJinFbk wrote: ↑04 Aug 2020, 08:01 As you are in Sweden, it may be your security system.
Does this car have a chipped key?

Today I could measure voltage at the gray connector. 12.5V. So sound from the pump.

Perhaps a cable is broken?

Mokarim · Post by **Mokarim** » 03 Aug 2024, 17:39

Hello
Did you find the problem and did you fix it
Because I had the same issue I’ve replaced the pompe and the injector and checked the battery and the keys but nothing until someone advices me to change the cable between the two pumps so I did and it turned on
The problem is I want to travel with it but I’m afraid that it will happen again .
So please tell me if u fixed the problem did it repeat the problem or not
Thank u