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'91 940 Turbo ... Loss of ALL power at cruising speed

My dad lets me use a '91 Volvo 940 turbo that loses power, all power, while driving down the highway. The first time it happened all the red lights on the dash went on; no engine power; no power steering or brakes, etc. I coasted to a off ramp and managed to get to a service station at the bottom of the ramp. AAA towed it to the family Volvo mechanic. He could find nothing. It started right up and I drove off. Since then it has happened three more times. Each time it starts up again after I somehow get it off the highway. It is currently at a dealer's in a distant city. They can find nothing either! Help! This is a dangerous problem! I'm in my last year of college. If I could afford it I'd just give the car back to my Dad and buy one that works. What I need is some idea of what's going on. Help!

Reply to
sactolarry
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There are several devices that need to be checked/replaced:

  1. Pull all the codes from the diagnostic socket. See:
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    instructions.
  2. Fuel Injection Combined relay (Failed/failing solder joints).
  3. Engine speed sensor if indicated by 2-1-4 code from above results
  4. Radio suppression relay (identical to the auxilliary fan relay). Turn key on, ground the cooling fan switch on the radiator. If thw fan runs swap the two relays and recheck. If the fan doesn't run replace both relays.
  5. Heat the ignition amplifier with a heat gun to see if the engine will stop running. If it does stop, cool it with a choke tester to see when it will restart.
  6. Check the wiring at the injector resistor pack.
  7. Heat test the coil.

In better tha 90% of the cases you will find the fix in one of the above choices.

Bob

Reply to
Robert Dietz

i would guess electrical...shorts, fuses, relays,...does it sputter at all? or, just a "shut off", as if someone "pulls the plug"...don't use dealers...use or find a good independent volvo mechanic...you will end up w/a better velue...have him/her use the car for a few days , until it acts up for them...just rent a car to replace it, or a lot of ind volvo shops will have a old 240 you can use for a few days...good luck!!! watch out for trucks following you w/this problem....

Reply to
~^ beancounter ~^

Start here for some diagnostic ideas.

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Harold

Reply to
grtdane63

So the engine is just stalling? You might be able to pop it in neutral and start it up while you're coasting if this happens again. As for why it's happening, I would suspect the hall sensor in the distributor may be failing. '91 940T is a nice car, hope you can figure out the problem.

Reply to
James Sweet

I experienced the same problem with my '92 940T. Replacing the fuel pump relay solved the problem.

Reply to
Barry Hobden

Had exactly this problem with a 93 945T. Turned out is was the "crankshaft position sensor" whatever that is. Got it fixed and has run fine since. Diagnosed by an independent Volvo shop (worked just on volvo's). Hope this helps. Howard

Reply to
Howard Nelson

I would start with a check of the charging system. Almost sounds like the alternator is crapping out when it gets hot.

Reply to
volvoguy

Reply to
HankL

Have you checked the fuel pump relay yet? If not then remove it from the relay tray and either resolder the main connections inside the relay or replace it with a known good item.

Cheers, Peter.

Reply to
Peter K L Milnes

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