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940T Stalling

Hi All,

Got a 1994 940 Turbo Estate. More and more regularly now it's cutting out. Tacho drops to zero (even if the wheels are still turning the engine) and Lambda light comes on. Leave it a minute or so and it will restart and drive normally - until it happens again.

Seems mostly to happen after a hot restart - not so often when cold.

Now the fault code that is set (although it doesn't set a code every time) is 1-4-4 - no fuel load signal.

My first thought was the ever troublesome fuel pump relay - but with the tacho dropping too it could be the ignition amplifier on the front inner wing... Or am I wrong?

Checked all the connections to the AMM and to the ignition module on the wing and to the sensor just downstream of the AMM - all look good - clean and tidy with a smear of grease on them.

Any thoughts would be jolly helpful!

Reply to
Simes
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You're right - the tach dropping while the engine is still rotating is a convincing indication of the ignition dying.

Three common trouble sources come to mind:

1) The crank angle sensor. In the 940T I think it is in the top of the bell housing, but it could be in the distributor. I'll leave it to the experts to clarify that. The crank angle sensor has caused more frustration than any other intermittent failure because it fails when it wants to and comes back when it wants to... no rhyme or reason. 2) The ignition module. Since ignition module problems are almost always heat related and you have done a basic check I don't think it's your problem. 3) In some models of Volvo in this era there is a "radio suppression" relay somewhere near the A/C drier. My 765T doesn't have one so I don't know what it looks like. User or Mike F would be the top sources of that sort of detail.

A less common source but too easy to overlook is a bad connection at the battery. If that maintenance is overdue now is a good time... but I don't think that is the problem.

Mike

Reply to
Michael Pardee

With me was same car same problem. Turned out to be the Crank position (angle?) sensor.

When it hard failed it left me stranded with a $100+ towing bill.

Howard

Reply to
Howard Nelson

I think you're right - crank position sensor for hall effect pickups, crank angle sensor when it is the optical type like my old Nissan had.

Mike

Reply to
Michael Pardee

Well - I've replaced the CAS and the ignition module - still exactly the bloody same!

Any more thoughts?

Reply to
Simes

Look for a black relay with 4 round pins, it's usually clipped somewhere near the shock towers under the hood. It's the next most common cause of these random stallings.

Reply to
Mike F

Cheers Mike - seems that the fuel pump relay was the culprit. A bit of resoldering and all appears well.

Reply to
Simes

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