'87 740 Turbo: Cuts out and will not restart for 40 min

Hi All

Some advice needed...

After only a few miles of driving the car will sometimes cut out (It cuts out quickly no splutter just dead) and not be able to be restarted for 30-40mins. During this time the starter will turn the engine over as normal but there's no hint of starting.

When it does cut out it is at low speed or waiting at lights, changing to second gear or soon after a slow speed corner - maybe at other times it happens but the momentum allows it to continue?

On one occassion it cut out after about 1 minute from cold - 50 yards, it wouldn't restart. I replaced the radio supression relay and it started first go. I thought this had fixed it as the problem didn't reoccur - two weeks later it's back. I have also replaced the fuel pump relay just in case.

I have read that it could be the hall or RPM sensor but have looked with a torch and felt around the base of the rear mounted distributor and there doesn't seem to be a hall sensor - based on what I've seen in pictures. There is a couple of electrical connectors suspended from wiring loom attached to the firewall nearby that terminate in a small block on top of the bell housing - is this an RPM sensor?

Any suggestions of which sensor I sould have or what could cause the car to die suddenly like this and not restart?

Ian

http://pic7.picturetrail.com/VOL188/...8/23744414.jpg


Ian,

It sounds as if you have the flywheel sensor.

The Hall Effect type can be identified by look at the ditributor base, if the black connector, (bottom left in the picture) is present you have the hall sensor (arrowed)

http://pic7.picturetrail.com/VOL188/...8/31553560.jpg

If you need to replace a flywheel sensor be very careful if the sensor is seized into its mounting bracket.

It is quite easy to apply sufficient force to break the bracket, replacement of this requires the splitting of the engine and transmission!!

For more info click the link below.

http://www.brickboard.com/FAQ/700-90...alIgnition.htm

Colin.

1990 740SE B200E/M47, remote C/Locking.

Thanks Colin,

The picture and URL helps, I must have the RPM sensor. I think I'll leave it in place for the time being until I've ruled out a few more suggestions from a Volvo garage...

Some of you might be interested:

- In tank fuel pump could be faulty. Apparently taking out its fuse (number 11?) should produce a different sound when starting. If this doesn't change the sound from the fuel pump it suggests the in tank pump might not be working, putting extra pressure on the main fuel pump. This case may explain the intermittent cut out's on low speed corners - if the tank is low, cornering could cause the fuel to move away from the pump intake and the main pump to suck air.

- Ignition Module (housed in aluminium box mounted inside fender near the battery) might be failing when the temperature under the bonnet is high. These are expensive new but if a second hand one were to fix the problem I could look at taking extra measures to ensure it keeps relatively cool.

Ian

http://pic7.picturetrail.com/VOL188/...8/23744414.jpg

Ian,
IF the problem is the ignition module (Volvo call it a power stage) they have been known to fail because a layer of rust/corrosion is blocking heat transfer to the bodywork metal.

It`s worth unbolting the unit from the inner wing and cleaning the heatsink and inner wing down to bare metal and apply grease or similar to prevent future corrosion.

If you do need a replacement I have a couple of spare second/hand ones, or

http://www.gsfcarparts.com/

list it (they call it a control module) for £42.50 + VAT.

My bet though is on the Rpm Sensor.

As to the pump problem, there is a short length of hose betwwen the
in-tank pump and the pick-up which is known to leak causing the pump to suck air when the tank is low on fuel.

Keep us posted.

Colin.

1990 740SE B200E/M47, remote C/Locking.

[BillB]

In addition to Colin's advice, it's worth checking the tach when cranking - the needle should jump a little. If it's dead and the fuel pumps don't hum suspect the hall/RPM sensor. If dead but the fuel pumps DO hum it's almost certainly the power stage. Regards.

P.S. I'm surprised an 87 has an RPM sensor - turbos only got them in 89 AFAIK.

[drivesavolvo]

Hi it is highly unlikely that you have the hall effect dizzy in your car. most of the turbo models had a different system.
With the fault you are expieriencing i would suggest you look at the following parts.

Ignition amplifier. although unlikely to be faulty.

Thermal timer. situated at back of inlet manifold on the head
or ECT sensor ( engine coolant temperature ) depending on which type of injection system you have. Mechanical has Thermal timer. electronic has ECT. Ect is a two pin sensor under the inlet manifold screwed into the head. the spanner to use is an open ended 17 or 19 mm (11/16 or 3/4 ). i have also expierienced a number of problems with the earth to the ECT breaking down, this would cause massive over fueling to your vehicle.

Fuel pump relay. This is found by removing the ashtray and back case. Remove cigar lighter and pull off sorrounding panel, put thumb into cigar lighter hole and pull off panel. 2 screws become visable. the bottom screw goes in straight and the top at an angle. undo both and remove the whole cigar lighter panel.
You should now have access to the relay box behing the fuses.
The fuel relay is situated on the left side in the middle row. (3 rows from from to back middle row on left.) should be green or white ( white was from 89 onwards if memory is correct) 2 inches tall by 2 inches lenght and 1 inch wide. remove the relay 6 pins should be visable ( 2 lines of 3 pins ) open the relay and look at all the contact points on the circuit board. you may find one on the switch unit has broken. if so either replace or re-solder the joint. hopefuly your problem will be cured.
If you should need further help or advice then mail me direct on Sakeje@onetel.com.
good luck, Keith

Thanks for the feedback so far.

I have dismissed the possibility of fuel pump problems for the time being, though next time it goes in for a service I'll get them to check. The car currently has half a tank of fuel but still dies when warm; it also doesn't show any other signs of fuel supply problems - according to a few volvo mechanics I've spoken to - poor running etc.

A friend has resoldered some of the joints in my ignition amplifier, it is the older style, contained in a black aluminium box (shown here to the left of the battery - mounted on the wheel arch)

http://www.zen15787.zen.co.uk/car/ig...amplifier1.jpg

I'll fit this later and see if I can still recreate the problem.

Below is a picture of the flywheel rpm/tdc sensors mounted on top of the bell housing. On this model there are two and they are apparently more expensive than the single rpm sensor fitted to the later models: £141 +VAT each ... ouch. I hope it's not these. If so is it worth going for second hand rather than forking out £330??

http://www.zen15787.zen.co.uk/car/rpm-sensor2.jpg

And their connectors coming off the loom running along the firewall:

http://www.zen15787.zen.co.uk/car/rp...connectors.jpg

Below is a poor picture of the (intake) side of the distributor, if it had the hall sensor I'd think it's connector or wires should be visible here.

http://www.zen15787.zen.co.uk/car/distributor1.jpg

I'll also look into the ECT and it's earthing as a possible cause, as suggested by Keith.

The fuel pump relay (which has been replaced as a precaution) is the white one. This should be correct (I hope so) as it was sold to me by a volvo dealer when I gave them the year/model.

I am restricted by tools, time, space and knowledge but hope to get to the bottom of this soon - While the problem exists I can't risk the 5 mile trip through central London to the mechanic I usually use. Thanks again for the advice and ideas so far.

Ian

PS The rpm/tdc sensors have yellow bands, I have read that the later ones had white bands and were more reliable does anyone know or can anyone confirm if they are interchangeable?

http://brickboard.com/FAQ/700-900/El...wheelSensorBad

I wanted to give some feedback as I'm up and running without failure. This might be premature as we have only needed to use the car on three occassions since I made a change - but each trip was long enough to cause the fault in it's previous state.

I'm not sure of the official name of the part that has been replaced but I refered to it as an Ignition Amplifier above. I sourced a second hand one for £40 as new they are apparently close to £400 and reconditioned £135 (with no guarantee they find a problem). I know this part might have or develop the same fault, but as there were a few parts that could have been the cause and the new cost for each solution was close to the value of the car I decided to go second hand with this part first.

This is reassuring, quote below taken from this URL on our site:

http://www.volvoclub.org.uk/tech/fuel_injection/efi.htm

"1984 to 1989 740/760 turbo models with Bosch Motronic part numbers 0261 200 022 and 0261 200 026. Symptoms... problems usually begin with intermittant on road breakdown or failure to start (no injector pulses or injectors operating continuously). Usual diagnosis is Motronic ECU failure which is replaced but problems continue.

More likely cause on these vehicles is failure of Luxor injection amplifier (rectangular black cast alloy box located immediately behind battery with connector uppermost. This box is part of traction control system and is fitted to all these vehicles whether or not traction control is specified. Failure is due to PCB design and quality control shortcomings."

Another point of interest: I mentioned in the previous post that a friend of mine (electronics engineer) resoldered some of the joints in this Injection Amplifier. When I reinstalled it I had a more immediate problem, the engine would start and run for about two seconds and then cut out, from this point it wouldn't restart for some time (can't say how long as I normally went back to the internet and manual before trying something else the next day). I may now get my spare reconditioned.

Thanks for the feedback.