'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!

 

There are several devices that need to be checked/replaced:
1. Pull all the codes from the diagnostic socket. See:
http://makeashorterlink.com/?Z63E358B3
for 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

 

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....

 

Start here for some diagnostic ideas.

http://www.brickboard.com/FAQ/700-9...tartFrequentStallorHesitationBasicDiagnostics

Harold

 

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.

 

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

 

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

 

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

 

There is a possibility that it is one of two things - the fuel pump relay or
the
crankshaft position indicator. Unfortunately, it starts back up and it is
very
hard to diagnose an intermittent problem. I'm not sure , but I think the
relay for
the fuel pump in question is whit - on the left side, and above the fuses in
back
of the ashtray.
The crankshaft sensor is a round devise, it stick up out of the transmission
bell
housing and has a small black wire attached that plugs into the middle of a
harness
in the center engine compartment firewall just below your windshield. There
are also
two black relays on the drivers side - located under your head light next to
the radiator
that need to be swapped. They are both the same.
My guess is that you have the white relay problem - if you are rich, get it
at Volvo -
if not, go to a bone yard and solve your problem for $10.00. If it happens
to
be the crankshaft sensor, it should be $20.00 at the same bone yard. Good
luck / Hank
BTW --- been there / done that......

 

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.