Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

Jeremy] Symptoms in my turbo were cutting out and dieing when driving then
restarting with no problems, not starting after sitting 8 hours and being totally flooded.
Fuel was weeping out the manifold! The cause of my problems: The power wires from
the injector to the turbo injection resistors were shorting together or to ground (note:
non-turbo cars do not have these resistors). This would cause the injectors to open
and stay open all the time in one or more cylinders. I found this by attempting to test
continuity through the wires and in the process of disconnecting the next connector it
would cause a loss of continuity in the connector I had just checked. Lesson-
disconect all connectors so you don't get the chance for a false good reading due to
an unknown short between wires. In another case, the wiring harness for the injectors
was rubbing against the bottom of the valve cover and had worn through three of the
injector's wiring. Now the solution: Replace the wires from the injectors to the resistor
pack in the forward left side of engine compartment and the wires going to the
connector that feeds thru the fire wall. The four wires going to the firewall connector
are the signal wires that give a ground to the injectors. They all end up at the same pin
so if you want to connect them at the injectors and just rum on wire to the plug that will
work too. I routed the new wires along the top of the engine away from heat sources.
Splice the new wires as close as you can to the existing connectors if you are not
planning to replace them.
760T Misfires; FI Resistor Pack Defective. [Symptom:] My 86 Volvo 760 turbo is
running very rough.. when I tested the cylinders the #2 cylinder wasn't firing. After
many hours of frustration I found a relay which is located next to the battery. This relay
is a little box with four cylinders in it The cylinders are about 3 inches long with a
radius of about 3/8 of an inch. five wires go into the box One attached to each cylinder
and one going down the center. I presume the lone one is the constant power. On this
box I saw one wire was dislocated. I re-attached this wire but the cylinder still wasn't
firing. I then took of another wire and the #4 cylinder stopped working. I then attached
the working electrode (off the box) to the #3 cylinder but it still wouldn't fire. I also
though have a periodic problem. Sometimes when I am driving normally my car will
start to misfire. If I floor it will eventually catch (3-4)seconds later. If I keep it floored it
does go.. but when I release the gas to 1/2 it starts to putter out. Could this be the
same problem? What is the name of this part? [Response:] What you are describing is
the resistor pack for the fuel injectors. Only the turbo's have them. The Volvo p/n is
3531339 and Volvo lists it for $59.39 dollars US. There is one resistor per injector. We
have seen the batteries corrode the connector over a period of time, from the lack of
battery maintenance.
Hot Start Problems: Faulty Hall Sensor. [Note from Steve Seekins:] Note that if your
car is a turbo, you do not have the crank position sensor, but you do have a hall effect