Volvo 940 wont start.

[Lolvo 940]

Yep that's what I thought too. Just he mentioned same issue with pump only priming once. Which was my original concern as my other 940 primes everytime you turn ignition on.
Will try the coil lead trick and let you know.

[aardvarkash10]

this thread is a classic example of why I obssess over fact-based diagnostics...

[aardvarkash10]

learn this off by heart.

[Lolvo 940]

Hi. Some success! ran a lead from battery to Blue wire on coil. There was another terminal to go on so didn't disconnect the blue. Started straight away runs fine. And could switch it off. So what should I check now?
Thanks for all your help

[aardvarkash10]

go to this page on the link I posted above. We are going to be referencing two pages:

LH-jetronic 2.4 multiport fuel injection system ( MFI ) ( B 200 FT, B 230 FT/GT )

and then a few pages down;

EZ 116 K Distributor ignition ( DI ) system ( B 200 FT, B 230 FT/GT )

Specifically, we are interested in two components. They are the fuel relay (2/13), and the radio suppression relay (2/12).

We are going to test them, systematically. Are you ready to follow?

[Laird Scooby]

Find the Radio Suppression Relay (RSR) again, and the socket it plugs into.Remove the relay from the plug and turn the socket over so you can see underneath and the wires that go into it. You should have :

Red
Green/Red
Blue/Yellow
Black

Get your voltmeter, connect the black -ve lead to battery earth and with the red +ve probe, check you have 12v on the red wire.

Now put the red +ve probe onto battery +ve and connect the meter -ve black probe to the black wire in the relay socket. Again you should have 12v.

Now switch the ignition on, +ve meter probe into the blue/yellow, -ve probe to battery earth and check you have 12v again.

If there's enough space to refit the relay, refit the relay and re-check these tests with the ignition on and also check the green/red terminal has 12v WRT (with respect to) earth (+ve probe on green/red wire, -ve probe to earth) - if all of these tests have given the results listed then assuming the RSR is ok, it should start.

However, somewhere along the line of those tests, you should have found an anomaly. This anomaly points the way to where the fault really lies.

At a guess, it's either going to be another duff RSR, corrosion in the relay socket or a bad earth connection on the blac wire from the relay socket to earth.
The earth point is the left hand inner wing somewhere behind the headlamp - there are several things grounded/earthed here, see page 12 of this pdf and the diagram is 31/2 :

http://www.myvolvolibrary.info/Tech_...C842%2Cnull%5D

Also see Pg7 of that, item 2/12 for the two possible locations of the RSR just to make sure.

[Laird Scooby]

Originally Posted by aardvarkash10

go to this page on the link I posted above. We are going to be referencing two pages:

LH-jetronic 2.4 multiport fuel injection system ( MFI ) ( B 200 FT, B 230 FT/GT )

and then a few pages down;

EZ 116 K Distributor ignition ( DI ) system ( B 200 FT, B 230 FT/GT )

Specifically, we are interested in two components. They are the fuel relay (2/13), and the radio suppression relay (2/12).

We are going to test them, systematically. Are you ready to follow?

I've hopefully just saved you some typing Ash! Posts crossed!

PS - we already know the fuel pump relay is ok, it primed and the engine fired and ran with my "Heath Robinson" test so it seems to be all about the RSR.

[aardvarkash10]

its a freakin' tag team event! Thanks for doing the hard yards - do you mind if I review your post?

Nope, You nailed it. :-)

[Rversteeg]

Does it run now as well WITHOUT the additional wire?
By putting 12 V feed directly onto the coil you bypassed the radio interference suppression relay 2/12. What you also did, is indirectly feeding the injectors as well, as they are fed via the same relay.

I would check the feed side of relay 2/12 (coming from the fuel pump relay) by measuring or by putting a direct 12V feed on the input side.
I would also check the relay by putting a bypass wire across relay 2/12.
If the engine does not run with a bypassed relay of 12V feed on the relay there is probably a fault in the wiring between coil and relay. From relay to injectors is not suspect, otherwise it would not run with 12V directly on the coil.

The ground side of the injectors is controlled by the ECU, just as the ignition amplifier, so it makes sense that you can switch off the engine with the ignition key.
It seems like you almost cracked it!

[Laird Scooby]

Originally Posted by Rversteeg

Does it run now as well WITHOUT the additional wire?
By putting 12 V feed directly onto the coil you bypassed the radio interference suppression relay 2/12. What you also did, is indirectly feeding the injectors as well, as they are fed via the same relay.

I would check the feed side of relay 2/12 (coming from the fuel pump relay) by measuring or by putting a direct 12V feed on the input side.
I would also check the relay by putting a bypass wire across relay 2/12.
If the engine does not run with a bypassed relay of 12V feed on the relay there is probably a fault in the wiring between coil and relay. From relay to injectors is not suspect, otherwise it would not run with 12V directly on the coil.

The ground side of the injectors is controlled by the ECU, just as the ignition amplifier, so it makes sense that you can switch off the engine with the ignition key.
It seems like you almost cracked it!

If you have a look 3 or 4 posts up, you'll see i've added a test procedure to find out whether it's the RSR or the wiring.

Because of the wonderful, unpredictable nature of back-feeds when doing a "Heath Robinson" test there was a slight question over it switching off as normal - theory says you would be right that the engine could be switched off with the key but i have known it to keep running.