Dead fuel pump relay? - dead car!! - Page 2

Dr. Rog · Jul 1st, 2011, 17:40

Fuel injection relay swapped in and out - no action
Ignition amplifier swapped in and out - no action.

Crank sensor is £40 and cannot be ordered until Monday.

Somehow I missed getting that of my "donor" car

I think I need a chap who knows what he is doing aka professional help.

Steve940estate · Jul 1st, 2011, 17:50

Is it not starting now ?

Have a look at the rev counter. It its doing something it might not be the crank sensor. I'm actually assuming that the crank sensor triggers the rev counter but thinking about it that might not be the case as most cars are run off the alternator.

Is there a spark ?
Have you tried wiggling the crank sensor wires ?

Another thought is the ignition module down near the injector relay but as you have swapped this it can't be.

If it isn't starting at the moment you might have half a chance of finding the fault if it's something a bit different.

Steve940estate · Jul 1st, 2011, 18:24

I'm guessing a bit really so as you say it might be worth getting someone who knows what they are doing.
I'd offer my spare crank sonsor but it's the one that I took off the car when it was playing up so I don't know if that would be of much help to be honest.

Hope you find something.

MTerry · Jul 1st, 2011, 18:32

Here are some quick checks. I know this because my 740 was towed into my office two days ago. As mentioned, if you crank the engine and the tach bumps up and down, the crank position sensor is working. If the tach's dead, there's your problem. The CPS drives both of them. Get somewhere quiet and turn the key to KP II. The in-tank pump should prime and you should be able to hear it. It's that hum you hear coming from the rear when you turn on the ignition. If you don't hear it, check the wiring going into it for power. If it has power, it's the pump; and if it doesn't it's probably the relay. Mine has power but doesn't work so I'm getting a new pump this evening and installing it in the office parking lot tomorrow. If all that checks out, check to see if the in-line pump just in front of the rear wheel is working. You might also want to check the fuel filter. Good luck.

Dr. Rog · Jul 1st, 2011, 19:26

Quote:

Originally Posted by MTerry

As mentioned, if you crank the engine and the tach bumps up and down, the crank position sensor is working. If the tach's dead, there's your problem. Good luck.

Tried again - watching the tacho - not a flicker of movement.

Why did I not notice that before.

Are we absolutely sure about this? even for a '96 car?

I will ring round the DIY suppliers tomorrow.

Steve940estate · Jul 1st, 2011, 19:58

I don't want to say its the problem and waste £40 of your money. I will have a look at te wiring diagram to see where the signal comes from as I am doubting what I thought was right, especially as it isn't my money.
If you get stuck and can't get anything locally I could bring the one I have to try or even pick one up near me.
I'm busy on Saturday but will be around and about, might be able to lend a hand Sunday.
I've got Camberley Auto Factors and Doset Autospares near me plus another I can't remember the name of.

Dr. Rog · Jul 1st, 2011, 20:52

Quote:

Originally Posted by Steve940estate

I don't want to say its the problem and waste £40 of your money. I will have a look at te wiring diagram to see where the signal comes from as I am doubting what I thought was right, especially as it isn't my money.
If you get stuck and can't get anything locally I could bring the one I have to try or even pick one up near me.
I'm busy on Saturday but will be around and about, might be able to lend a hand Sunday.
I've got Camberley Auto Factors and Doset Autospares near me plus another I can't remember the name of.

That's a very kind offer. Its not your responsibility, MTerry says its so and I am sure someone else will confirm. Lets see what tomorrow brings.

Steve940estate · Jul 1st, 2011, 20:56

I've been looking.

According to the wiring diagrams I have the rev counter is connected to the w terminal on the alternator and gets power from the ignition switch. The third wire is the earth and is connected to the in tank fuel pump in a round about way. I doubt this has any significance though it's just how it's shown on the diagram.
I have just tried my car and until the engine fires and runs the rev counter is still. I hadn't realised it didn't move at all so I don't really understand where the crank sensor comes into it.
Someone explain please as I am sure I have read about it somewhere.

Steve940estate · Jul 1st, 2011, 21:23

More thoughts.

As your car is one of the later ones it has the later built in alarm fitted to it I think.
My early cars alarm immobiliser just works on the starter circuit but I wonder if the later ones are a bit more clever.
There is quite a bit on Vadis about the later alarms , ways to get the car going if the immobiliser goes wrong etc.
I wonder if the later alarms will actually make the car cut out if they go wrong

RealEstate · Jul 2nd, 2011, 00:30

Dr R, did you check out the FAQ?

EG see "Watch the tach carefully when a stall occurs. If it drops to 0 even before the engine winds down then that would indicate loss of ignition pulses to the coil negative terminal. Primary suspects would be the power stage or the crank position sensor. If tach tracks the engine speed as it winds down then that would indicate a fuel injection problem. Suspect radio supression relay or loss of fuel pressure due to relay or pump. "

Jul 1st, 2011, 17:40	#11
Dr. Rog Master Member Last Online: Oct 21st, 2017 22:15 Join Date: Aug 2010 Location: Kingsclere	Fuel injection relay swapped in and out - no action Ignition amplifier swapped in and out - no action. Crank sensor is £40 and cannot be ordered until Monday. Somehow I missed getting that of my "donor" car I think I need a chap who knows what he is doing aka professional help. __________________ Cheers Rog Previously owned 1996 940 SE auto and GLE manual, both B230FK estates.

Jul 1st, 2011, 18:32	#14
MTerry Bored Member Last Online: Nov 23rd, 2020 19:46 Join Date: Oct 2006 Location: Baltimore, Maryland, USA	Here are some quick checks. I know this because my 740 was towed into my office two days ago. As mentioned, if you crank the engine and the tach bumps up and down, the crank position sensor is working. If the tach's dead, there's your problem. The CPS drives both of them. Get somewhere quiet and turn the key to KP II. The in-tank pump should prime and you should be able to hear it. It's that hum you hear coming from the rear when you turn on the ignition. If you don't hear it, check the wiring going into it for power. If it has power, it's the pump; and if it doesn't it's probably the relay. Mine has power but doesn't work so I'm getting a new pump this evening and installing it in the office parking lot tomorrow. If all that checks out, check to see if the in-line pump just in front of the rear wheel is working. You might also want to check the fuel filter. Good luck. __________________ Elphie - '98 V70 AWD, also Polar White Sophie - '09 XC90 V8, Shadow Blue Gloria - '93 244 in Ruby Red Metallic Sandy Blu - '07 C70, Celestial Blue

Jul 1st, 2011, 20:56	#18
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I've been looking. According to the wiring diagrams I have the rev counter is connected to the w terminal on the alternator and gets power from the ignition switch. The third wire is the earth and is connected to the in tank fuel pump in a round about way. I doubt this has any significance though it's just how it's shown on the diagram. I have just tried my car and until the engine fires and runs the rev counter is still. I hadn't realised it didn't move at all so I don't really understand where the crank sensor comes into it. Someone explain please as I am sure I have read about it somewhere. Last edited by Steve940estate; Jul 1st, 2011 at 21:07.

Jul 1st, 2011, 17:50	#12
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	Is it not starting now ? Have a look at the rev counter. It its doing something it might not be the crank sensor. I'm actually assuming that the crank sensor triggers the rev counter but thinking about it that might not be the case as most cars are run off the alternator. Is there a spark ? Have you tried wiggling the crank sensor wires ? Another thought is the ignition module down near the injector relay but as you have swapped this it can't be. If it isn't starting at the moment you might have half a chance of finding the fault if it's something a bit different.

Jul 1st, 2011, 18:24	#13
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I'm guessing a bit really so as you say it might be worth getting someone who knows what they are doing. I'd offer my spare crank sonsor but it's the one that I took off the car when it was playing up so I don't know if that would be of much help to be honest. Hope you find something.

Jul 1st, 2011, 19:58	#16
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	I don't want to say its the problem and waste £40 of your money. I will have a look at te wiring diagram to see where the signal comes from as I am doubting what I thought was right, especially as it isn't my money. If you get stuck and can't get anything locally I could bring the one I have to try or even pick one up near me. I'm busy on Saturday but will be around and about, might be able to lend a hand Sunday. I've got Camberley Auto Factors and Doset Autospares near me plus another I can't remember the name of.

Jul 1st, 2011, 21:23	#19
Steve940estate Steam Driven PC Owner. Last Online: Mar 4th, 2024 23:50 Join Date: Dec 2004 Location: Not sure.	More thoughts. As your car is one of the later ones it has the later built in alarm fitted to it I think. My early cars alarm immobiliser just works on the starter circuit but I wonder if the later ones are a bit more clever. There is quite a bit on Vadis about the later alarms , ways to get the car going if the immobiliser goes wrong etc. I wonder if the later alarms will actually make the car cut out if they go wrong

Jul 2nd, 2011, 00:30	#20
RealEstate Master Member Last Online: Nov 4th, 2018 16:06 Join Date: Dec 2003 Location: Berkshire & N Wales View Photos By: RealEstate	Dr R, did you check out the FAQ? EG see "Watch the tach carefully when a stall occurs. If it drops to 0 even before the engine winds down then that would indicate loss of ignition pulses to the coil negative terminal. Primary suspects would be the power stage or the crank position sensor. If tach tracks the engine speed as it winds down then that would indicate a fuel injection problem. Suspect radio supression relay or loss of fuel pressure due to relay or pump. "

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