940 2.3 LP turbo cuts out - help!

salsaman · Jul 15th, 2009, 00:10

Just bought 940 2.3. LP turbo Estate 1996 144,000 miles. Sometimes it cuts out while on the move and wont re-start. If I turn the ignition off and wait a minute or two it will re-start. It's not miss-firing while driving, but when it's warmed up the idle increases from around 750 rpm, when cold, to just over 1000 rpm, when hot. Help would be much appreciated - I had to push it to the kerb, fully loaded, on my own this morning, when it cut as I approached the lights. Did it again on the way home at around 20 mph.

gpl1968 · Jul 15th, 2009, 09:30

Most probably the fuel pump relay which which can be found here:

Re-solder the joints on the pcb.

Steve940estate · Jul 15th, 2009, 09:59

My car does the high idle thing. I find that if you give it a minute to idle after starting it seems ok.
Not sure about the stall though, could be idle control valve related seeing as you have an idle problem, crank sensor, injector relay (noise suppression relay) or the fuel pump relay. Ignition switches can also give problems.

salsaman · Jul 17th, 2009, 01:22

Thanks.
Do you mean fit a new relay as well as soldering the PCB? Tried tapping the relay and wiggling it while the engine was running, but this didn't induce it to cut out.

RollingThunder · Jul 17th, 2009, 10:41

The fuel pump relay powers both the fuel pump and the lambda sensor heater. Unfortunately, the relay rating is only just adequate for this application - which means that it gets quite hot. The cycle of heating up when running, and cooling off when not running causes the PCB inside the relay to expand and contract - this eventually fractures the soldered joints on the PCB, so the next time the engine is run, the joints open and the electrical circuit is broken - meaning no fuel pump. Once the relay cools down, the joints re-connect and you can start the engine again.

The free fix is to open the relay and resolder these joints. I'd say it works in over 50% of cases. The other option is to buy a new relay - it used to cost around £30 from GSF, but I sold my 940 a few years ago so have lost track of prices now

I bought a new relay, and re-soldered the original one to be used as a spare which I carried around with me.

Of course your problem may have nothing to do with the relay - but I'd give it a try as its a very common problem.

Regarding the idling issue, I'd recommend checking all the vacuum hoses for splits, and probably would also clean the throttle body ensuring that the bypass tracts are clear - you can then reset the idle speed back to 750rpm and see if that improves matters.

Hope this helps.

TonyS9 · Jul 17th, 2009, 17:51

I thought the relay problem was cured from 94 or so, but I'm not sure. No problems in my 95+96 940s.

An unusual cutting out problem is a tear in the dump valve diaphragm (the 3 bolt part on the turbo facing the air filter). But its more of a conking out rather than sudden cutting out, if you keep it reved up after applying power and slowly reduce the revs it doesn't conk out at idle. It can't idle while the pressure is wrong in some part of it.

salsaman · Jul 17th, 2009, 22:46

Thanks - very helpful. will resolder joints in relay and order a new one from Parts for Volvo Online. They quote £9 to £13 depending on colour of relay. As I have only just bought the car I think I will sevice it with plugs, filters etc,etc. Also will check all the points everyone has kindly put forward.

Jul 15th, 2009, 00:10	#1
salsaman New Member Last Online: Jun 28th, 2010 17:32 Join Date: Apr 2009 Location: croydon	940 2.3 LP turbo cuts out - help! Just bought 940 2.3. LP turbo Estate 1996 144,000 miles. Sometimes it cuts out while on the move and wont re-start. If I turn the ignition off and wait a minute or two it will re-start. It's not miss-firing while driving, but when it's warmed up the idle increases from around 750 rpm, when cold, to just over 1000 rpm, when hot. Help would be much appreciated - I had to push it to the kerb, fully loaded, on my own this morning, when it cut as I approached the lights. Did it again on the way home at around 20 mph.

Jul 15th, 2009, 09:30	#2
gpl1968 VOC Member Last Online: May 5th, 2024 23:42 Join Date: Jun 2007 Location: Wirral View Photos By: gpl1968	Most probably the fuel pump relay which which can be found here: Re-solder the joints on the pcb. __________________ Gavin 1997 945 CD (B230FK) [RIP: 1991 945 Turbo (B230FT) 1992 945 SE turbo (B200FT)]

Jul 17th, 2009, 10:41	#5
RollingThunder Grumpy Old Git Last Online: Jun 18th, 2024 12:28 Join Date: Dec 2004 Location: South Yorkshire View Photos By: RollingThunder	The fuel pump relay powers both the fuel pump and the lambda sensor heater. Unfortunately, the relay rating is only just adequate for this application - which means that it gets quite hot. The cycle of heating up when running, and cooling off when not running causes the PCB inside the relay to expand and contract - this eventually fractures the soldered joints on the PCB, so the next time the engine is run, the joints open and the electrical circuit is broken - meaning no fuel pump. Once the relay cools down, the joints re-connect and you can start the engine again. The free fix is to open the relay and resolder these joints. I'd say it works in over 50% of cases. The other option is to buy a new relay - it used to cost around £30 from GSF, but I sold my 940 a few years ago so have lost track of prices now I bought a new relay, and re-soldered the original one to be used as a spare which I carried around with me. Of course your problem may have nothing to do with the relay - but I'd give it a try as its a very common problem. Regarding the idling issue, I'd recommend checking all the vacuum hoses for splits, and probably would also clean the throttle body ensuring that the bypass tracts are clear - you can then reset the idle speed back to 750rpm and see if that improves matters. Hope this helps. __________________ S40 2.4i '07 Japanese import '96 850R - https://www.volvoforums.org.uk/showthread.php?t=312484 Ex Danish Embassy '96 940 GLE LPT - https://www.volvoforums.org.uk/showthread.php?t=326071 Last edited by RollingThunder; Jul 17th, 2009 at 10:46. Reason: Adding para on idle speed

Jul 15th, 2009, 09:59	#3
Steve940estate Steam Driven PC Owner. Last Online: Jun 11th, 2024 15:05 Join Date: Dec 2004 Location: Not sure.	My car does the high idle thing. I find that if you give it a minute to idle after starting it seems ok. Not sure about the stall though, could be idle control valve related seeing as you have an idle problem, crank sensor, injector relay (noise suppression relay) or the fuel pump relay. Ignition switches can also give problems.

Jul 17th, 2009, 01:22	#4
salsaman New Member Last Online: Jun 28th, 2010 17:32 Join Date: Apr 2009 Location: croydon	Thanks. Do you mean fit a new relay as well as soldering the PCB? Tried tapping the relay and wiggling it while the engine was running, but this didn't induce it to cut out.

Jul 17th, 2009, 17:51	#6
TonyS9 Premier Member Last Online: Today 01:14 Join Date: Jul 2009 Location: Holywood	I thought the relay problem was cured from 94 or so, but I'm not sure. No problems in my 95+96 940s. An unusual cutting out problem is a tear in the dump valve diaphragm (the 3 bolt part on the turbo facing the air filter). But its more of a conking out rather than sudden cutting out, if you keep it reved up after applying power and slowly reduce the revs it doesn't conk out at idle. It can't idle while the pressure is wrong in some part of it.

Jul 17th, 2009, 22:46	#7
salsaman New Member Last Online: Jun 28th, 2010 17:32 Join Date: Apr 2009 Location: croydon	Thanks - very helpful. will resolder joints in relay and order a new one from Parts for Volvo Online. They quote £9 to £13 depending on colour of relay. As I have only just bought the car I think I will sevice it with plugs, filters etc,etc. Also will check all the points everyone has kindly put forward.

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