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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20388
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Volvo 940 turbo engine stops on road while drivingcannot

Customer Question

Volvo 940 turbo engine stops on road while driving
cannot re-start immediately -engine turns but sounds like fuel starvation
after 5 minutes it will re-start ok
has been like it for a year
two temperature sensors have been changed -made no difference
something stops the fuel supply i believe
Jimmie ***
Submitted: 7 months ago.
Category: Car
Expert:  Matt replied 7 months ago.
This sounds like an electrical actuator or sensor at fault .Usually when you can cycle the ignition key on / off and then restart the engine and the fault is gone temporarily this indicates that this is an electrical component causing this issue. This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;Airflow meterCrank position sensorCam position sensorO2 sensorThrottle position sensor unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40 and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins. Check the resistance of the spark plug leads ( 13-15Kohm / metre) and replace if any doubt or high resistance - Also replace the spark plugs if any of them fail this checklist: Also its worth checking that the electric pump that feeds the injectors is working correctly, it should run for a few seconds then switch off when you first turn the ignition on. If the connections to this are corroded or damaged then the pump could stop at any time. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, ideally measure the voltage at the pump and check its getting 12V
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20388
Experience: BEng hons Mech engineering, in auto industry 22 years
Matt and other Car Specialists are ready to help you
Customer: replied 7 months ago.
Thanks Matt
I've now read your response - and posted a 5-star rating. Thank You.I believe my local garage mechanic was "on the right track" when he
changed the two temperature sensors. He thought that if these were faulty
the "engine management" would think the engine was over-heating and cut
the fuel supply. Your comprehensive checklist will provide my garage
mechanic with an efficient programme for chasing this elusive fault, which
has been causing some anxiety on the roads.I will be taking the car into the garage as soon as they have a slot.
Meantime, if you have any further thoughts to add to the list, I would be
grateful to receive these by e-mail.Once again, many thanks.
Customer: replied 7 months ago.
Hi Matt
I should have said originally that when my engine dies on the road it is my strong impression that it is never under heavy power. It seems it happens when I have eased off on the gas, and I suddenly become aware of the drag of the engine - or I have taken my foot off the gas completely as I approach a roundabout or a crossing. Does this additional information narrow or broaden the search.
Expert:  Matt replied 7 months ago.
hello its possible that if its only occurring on the over-run then it may be a wiring loom thats being moved as the engine moves?

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