Electrics: CEM or not?

[MWMan]

Hi all

A few years ago I started having problems with the CEM overheating and causing issues. I fitted a PC fan on the unit and this prevented the problems from occurig again. However, I knew I would have to get it refurbished at sometime, so I took the plunge a week or so ago and sent it to Volvo Diagnostics to have it refurbished. Car started up fine when I refitted it, but I didn't take it out, as I was in the middle of a heater blower motor change.

When I did take the car out, it was to go and fill up at my locoal petrol station. About a mile from home the car engine stopped and I could not get it going again. Called the AA out and he determined that it was definately a fuel supply issue. If he squirted quick start down the intake, the car fired up straight away. Anyway, got towed back to my house to start fault finding.

1. The fuel pump is OK. Put 12v on there and proved the pump worked.
2. Disconnected the fuel filter outlet and put on some tubing and started the pump. I was able to half fill a gallon container.
3. Tested the fuel pump relay by swapping it withg the Fog lamp relay - both OK.
4. Tested the continuity of the 12v output wire at the relay through to the pump - no issue.
5. Put VIDA on to check fuel pump relay operation when trying to start - it shows the relay operating.
6. Check for volts at the pump when trying to start - NO VOLTS

I am coming to the conclusion that something has gone wrong in the CEM. VIDA doesn't show a fault, but I am at a loss as to what else it could be. I will contact Volvo Diagnostics after the holiday weekend, but before I do, I was wondering if I am missing something?

Any thoughts would be appreciated.

[mcfe]

While I cannot give advice on that matter I would definitely like to know why it would have overheated.

Maybe just maybe the foam seal around your heater core has disintegrated and was blowing warm air over it?

[MWMan]

CEM abberations seem to be fairly common on these cars. The original faults I had, seemed to happen on cold dark mornings when there was a lot of electrical load - heated seats, windscreen wipers, lights etc. or during the summer on a hot day. Fitting the PC fan on the unit alleviated these issues, so I assume some components in there don't like getting warm as they age.
Quite the opposite of me !

[mcfe]

One last solution is to take it out and re-install it again(loose wire/plug). If that doesn't fix it then maybe its time to take it back to the refurbishers, they clearly did something wrong.

[MWMan]

I have my grandaughter with us the rest of the week, so I'll take a break from the car and get back to it at the weekend. I'm going to start from scatrch again on the fault finding and be absolutely sure I have gone through this correctly. I don't want to say it is the CEM refurb that has caused the problem if it is something I have missed. I'll update next week.
Thanks