Hi guys

Hoping I could get some help with my sick volvo.

I've had her a few years, but has had little use over the past couple months.
Battery went flat from sitting. I charged up a new battery and swapped them over. Car fired up for about 5 seconds then died. Fiddled about checking some electrics and what-not and she fired up after that, only to not start the following time - seems its now got an intermittent starting issue, which has now degraded to a complete non-starting issue.

Car has single pump in the tank (Regina?)

I have checked:

1. Spark = Yes, getting spark.
2. Fuel = No.
So, checked power to fuel pump, none.
Then connected a hot wire to the fuel pump and pump fires up instantly. So pump is ok.
3. Fuel pump relay (blue one) - swapped this out for two others, no joy.
4. ECU, read that the fuel pump dirving circuit in the ECU can die with age, so swapped with a replacement ECU, with all the same part numbers (although the sticker was green, and writing on it indicates its from a 740 Turbo).... no joy, did not start the car.
5. Used multimeter, checked pin 30 on the fuel pump relay socket, and it goes hot when ignition is turned on, but as soon as I crank the car, the voltage drops to ZERO whilst cranking, stop cranking it jumps back to 12V+ - Needless to say forcing the contact closed whilst cranking did not energise the pump whilst cranking....

It seems to me that some signal is stopping power getting to pin 30 for the fuel pump relay whilst cranking the car....

Continuity has been tested between the fuse 1 and the fuel pump relay socket... and also the wiring between there and the fuel pump and all checks out...


Any help muchly appreciated!

Best

 

Hi Guys
No worries on replying here. I have fixed the issue. I saw online that there is a Fuel injection relay, big white one which outputs a signal to the fuel pump relay, so opened that relay up and found 4 dry solder joints. Re-flowed the solder on all of them and it fires right up now.

What baffles me though, is relay M, the supposed fuel pump relay does not seem to energise (left cover off relay and there is no movement from the contacts) when cranking/running/ or ignition on... the fuel pump is running though as I have listened to it, and tested with a meter, its getting 13.8v... so out of curiousity, is it possible relay M is not the fuel pump relay?

 

98 940's were never sold here in the USA (1995 wsa the last year) and the LPT version was never sold here either. but, 1995 non-turbos were Bosch with only one fuel pump, so I don't doubt 1998 LPT would be much the same. afaik, Regina was done and history by then.

on the last couple years of USA non-turbo 940's, they did away with the big dual relay in position "E", and went with a conventional single relay in position "M" for the fuel pumps only... the 'main injection relay' functionality was moved to the 'Radio Suppression' relay that was already under the hood.


as far as your 1998 goes, I dunno, I have no wiring diagrams for those. But if you have a relay "E", that should be both main and pumps, and I dunno what relay "M" is. on some earlier years it was used for rear fog lamps.

 

ok, on my copy protected DVD of greenbooks, I found a 1998 940 wiring book in Swedish. Now, I can't read Swenska, but it shows position M as being either relay 2/49, 2/3, or 2/34, and says those are... [translations by google]

2/49 - Dimbakljus (vänsterstyrda bilar) [rear fog light (left hand drive)]
2/3 - Reducerat halvljus (DIM-DIP) (Storbritannien) [reduced low beam (DIM-DIP) (UK)
2/34 - Dimframljus (Japan 1998) [??? dim something light?]