87 760Turbo Starts But Dies

Hello group,

We acquired a 1987 760 Turbo wagon last year. Just under 160,000 miles,
seemingly reasonable shape but no promises made. Had been used for mostly
short local trips last few years. A sticker indicates that the belts were
replaced at about 150,000 miles, a year earlier.

Early last year, the car failed to start for the previous owner at 156,800.
Mechanic replaced fuel pump relay, fuel pressure regulator, cooling temp
sensor and distributor ignition assembly ($276). In May, the car failed to
start again, just after doing over 200 highway miles. Another mechanic
found engine block soaked with gasoline and cleaned everything up again. He
replaced the fuel pump ($213) to try to solve the flooding problem.

The next day, the car passed state inspection for safety and emissions. A
high point of our turbo brick ownership to date. A week later, it was dead
in the driveway again and this time we towed to a Volvo dealer.

The dealer mechanic also found fuel pouring out of the cylinders - stopped
when injectors were unplugged. He checked compression and found all
cylinders over 140 psi. They spent a lot of time checking ground wires and
cables and repaired several shorts. But still no clue on the fuel problem.
So we bit the bullet and replaced the Electronic Control Module ($993) and
car left dealer running well.

In the next six months we drove another 2,000 miles or so, mostly short
trips, some highway. But with the onset of winter it started dying with
growing frequency and now it's reached the point where I haven't made it out
of the neighborhood in two weeks.

When left to sit for a time, the car starts quite readily but will die
within 35-45 seconds. If I do manage to get the car warmed up and try to
drive, it lately tends to die suddenly while in motion. When the
start-die-restart process is repeated too many times, the car refuses to
start at all as if flooded -- yet I don't smell gas when I stick my head
under the hood. Part of the problem is when the idles speed swings up and
down "searching" it tends to die at the low end of the search. But that
happens less often than the engine just quits with no provocation. And that
seems to be happening with increasing regularity.

The question is what to investigate to find the cause of this. I have
acquired a shop manual and begun getting familiar with the basics. I would
like to make this car run well enough to do at least a few more thousand
miles of short trips -- it's getting to be a personal challenge!

Therefore, I would greatly appreciate the value and benefit of any guidance,
suggestions, lessons learned, etc. regarding where I should start looking
for a solution to this problem. I have read a lot of good advice here so
I'm hoping for a bit more to help me target my effort. Thanks very much.

 

I'm somewhat new to the VOLVO game, but I have a 1990 Turbo wagon and
one of the things everyone who knows anything said to me was to check
the wiring harnesses. Apparently they were made with rather shabbily
during the mid 80's and can lead to a wide range of problems for the
car.

 

On a Volvo flooding can only occur a few ways. If the control unit is
bad and won't pulse the injectors, if the diaphragm is ruptured in the
fuel pressure regulator raw fuel pours directly into the intake
manifold, or if the coolant temperature sensor is defective in such a
way that it thinks the temperature is very cold but warmer than -84*F.
The third option could be due to a faulty or defective engine harness.

First, however, you need to find out whether the engine loses fuel
first, or spark first, and then once it won't start whether it's missing
fuel or missing spark or both. Then we can proceed.

Bob

 

I have an '87 740 turbo (viturally the same car as the 760) and had the same
problem with the car starting, but not running. The problem was the fuel
pump relay. It is a plug-in module under the hood that cost less than
$20.00. It takes only about 3 minutes to remove one and plug in a new one.

As for the late '80's volvo being poorly made. I bought mine new in '87 and
after 100K miles it continues to run fine without a single major problem.
When it does break, it is far easier and cheaper to repair than my 2001 V70
Turbo.

 

The cars aren't cheaply made, the engine wiring harnesses are made with
poor insulation though. If yours hasn't died due to a rotting harness
yet, it will.