1990 760 Turbo wagon dies at random!

This is going to sound like a repeat of an earlier situation with
another car.

We have a 1990 760 Turbo (intercooler) wagon with 147k miles. The
vehicle will die at random, stop lights, freeway, city streets, etc.
It will usually start up once I coast to a stop, or it will take a
minute or so before it starts. It can go months before it dies, and
then it may die every day for a week or so.

I’ve had 3 different mechanics try to solve the mystery. So far, we
have replaced:

System relay
Air Mass Meter
Spark Plugs
Cap & Rotor
Plug Wires
Speed sensor
Power Amp Ignition
TB Gasket (during cleaning I’m assuming)

No luck with fixing the problem so far. Want to take a crack at it?

I just checked the fault codes and they read 2-3-2 & 3-1-1.

Thanks for the help!

 

2-3-2 suggests fuel supply anomaly and 3-1-1 suggests Speedometer signal
absent. It is possibly curable by thoroughly cleaning the inlet tract (from
filter to manifold including Idle Air Control Valve). This is a two yearly
maintenance job. Also check all connections to and from ECU and ICU plus all
sensors that feed to the ECU/ICU.

Cheers, Peter.

 

My volvo had a faulty car alarm that caused the car to cut ou when you were
driving it.

 

Wild guess, based on the lack of pattern and the random amount of time
before it restarts - crank angle sensor (or whatever the Hall effect device
is called in the 1990 765T). It is infamous for doing that and being the
very devil to catch in the act. One clue - if the tach kicks when you try to
restart but the engine doesn't fire, it isn't the Hall effect dealie or
anything in the ignition. Has the fuel pump relay been resoldered or
replaced yet?

Mike

 

I had a hot-start/run problem in my 1989 760 turbo that proved to be the
"charge air overpressure switch". Basically, it's a vacuum switch that cuts
power to the fuel pumps if your turbo is blowing too much boost.

It's the first powered link in the fuel system after the ignition switch,
and if it's faulty it's a real bugger to diagnose. I just bypassed it with
two alligator clips and a scrap of wire, and the car starts and runs fine
now. IPD doesn't sell it, and my local Volvo dealer was no help in trying
to order one.

The Haynes manual (which only covers up through '88, I believe) had the part
living up under the dash around the brake pedal cluster, but by my 1989, the
Volvo engineers had moved it to a strap on the coolant overflow tank under
the hood. I suspect it was the dramatic heat cycles that killed it.

Best of luck!
--Dale

 

Thanks for the input! No alarm system is the Volvo, so I can rule
that out.

 

I’ll try cleaning the inlet tract this weekend!

As for the fuel pump relay, I don’t think that has ever been changed.
Where is this located?

The Volvo just quit on me this morning at a stop light. Just died.
It did start on the second try. Total time that elapsed was about 20
seconds. No check engine fault this time. I had been on the road for
about 35 minutes when it happened.

 

The fuel pump relay on your 760 is behind the passenger side kick panel on
the side of the Centre Console. It sits on the relay panel which is mounted
vertically. The Fuel pump relay is The one on the top row between the top of
the double relay (headlights) and the foremost relay (Central Locking
system).

Cheers, Peter.

 

If it is the same location as my '85, it is in the center console. Remove
the ash tray and ash tray mount, exposing the fuses. The relay is on the far
left side (as you sit in the car); a rectangular white plug-in module in the
second row back (toward the nose of the car). They are notorious for
intermittent solder connections in the circuit board inside.

Mike

 

Sorry Mike but this is a 1990 (post facelift) model. The fuses are in the
end of the dashboard and cannot be accessed if the driver's door is closed
and the relays have their own special place as I have already described to
the gentleman.

Cheers, Peter.

 

Thanks for the info, Peter! Next time I'll know (if I don't forget between
now and then.)

Mike

 

Thanks for the help!

I replaced the Fuel Pump Relay this evening. When I pulled the
plastic covering off the old one, I did notice a small crack in one
solder joint. We shall see if that fixes the problem.

Stroller (aka Brian)

 

Something like this?

http://www.viatrack.ca/Misc/badcon2.jpg



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

 

DOES SILVER SOLDER HELP ?

 

Sorry John but it doesn't as it is harder than electricians solder and is
more affected by vibration.

Cheers, Peter.

 

I also have a 1990 760 Turbo wagon with the exact same problem. Mine
has 99.6K miles on it. It was serviced by a dealer until two years
ago when I bought the car.

This morning, running at 30 mph, the engine died. I put it into
neutral and tried to restart as I was rolling but it just kept
cranking. I was able to pull to the side of the road and stop. After
10 seconds, I cranked it and it started.

Another problem, which I thought might be related, is that you have to
crank the engine for about five seconds before it starts. However, it
you crank it for two seconds, then wait two seconds, it will start
immediately.

I am going to pull the diagnostic codes now and I’ll let you know if
they are the same ones you got.

Regards,
Jim O’Connell

 

bad fuel pump relay???

 

1-4-4 states " Load signal from fuel injection system absent. Did you check
all codes available on 2 (fuel) and 6 (ignition)? Port 4 is not normally
used in fault diagnosis of ECU/ICU problems.

The Volvo ignition power amplifier suffers similar problems to the late 80s
Fords. It is mounted usually at left front of inner fender and suffers
corrosion of the connector's connections and poor grounding (of both heat
sink and wire connection.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

 

Peter is correct, I checked on Port 2, not 4,---but got a 1-1-1. I
got the 1-4-4 on Port 6.

Does anybody else have any experience with the Volvo ignition power
amplifier? What does it look like?

 

I recently had the same issue with random stalling in my 1999 Volvo
S70 Turbo w/55,000 mi. I went to the Volvo dealership parts dept. and
bought a new fuel filter [$45], fuel pump relay[$85], and fuel
injection relay[$36]. I took the parts to Midas for installation and
also had a throttle body cleaning[$79] done.

Not only did it solve the problem, but I’m getting much better gas
mileage and the car accelerates much much better.

-Datakix