Often, I read brickboard entries with problems that people experience, and end up stabbing in the dark, trying to guess what the cause could be. Recently, I found myself in the same situation, after having my car die on the road. I found myself going through all the guesswork, trying to imagine what could be causing the no-start on my 1987 760 Turbo Wagon. There are a lot of blind alleys out there, and there is no substitute for an in depth understanding of how it all works. Barring that depth of understanding (which I definitely lack), a good alternative is a reliable and easy to follow, troubleshooting checklist.

One problem faced by spare-time do-it-yourselfers (myself included) is the lack of understanding of how all the electrical and fuel-related components interact with the computer-brained bricks we drive. Another problem is our unfamiliarity with technical nomenclature, reference to the same parts by different names, and the location of various components throughout our bricks.

The brickboard is by far, the best on-line technical information source that I’ve come across for detecting and repairing all sorts of foibles with Volvo mechanical and electronic components. With this in mind, I’ve prepared my 2 cents worth of experience gained by hit-and-miss diagnosis on one aspect of troubleshooting with one 700 series turbo brick – the dreaded no-start.

For anyone with enough patience to read through the text below, please feel free to correct errors I’ve made and fill in any blanks I’ve left. One reason I’ve put all this in writing is for self-assistance next time I will inevitably have to go through the basic testing procedures. Hopefully, these steps will also be of use to someone else, as well.

The following is an attempt to outline, step-by-step, the procedures I went through after my car abruptly quit, began to start again, and then refused to start. The fix here happened to be a faulty Hall Effect Sensor in my original distributor. However, the no-start symptom could have been caused by one or several of a number of problems.

Of course we should all follow the usual precautions. Example: for your own safety, stay away from any parts which might be moving, like the fan and drive belts. For the car’s sake, disconnect the battery when disconnecting and reconnecting electrical components like the air mass meter, so you don’t blow any on-board computing equipment. Be sure to turn the ignition key off when done with each segment of testing.

Experience with 1987 760 Turbo (186,000 miles) no start:

After 45 minutes of driving home from work on mostly local roads and streets, my car missed momentarily, a second time about a minute later, then it died. Pulled car safely off the road. Restarted car and it ran for about 5 seconds. Restarted 3 more times for 5-10 seconds each. The fourth time, no start.

Tried to restart 15 minutes later, no start.

Got a tow to my mechanic’s, luckily only three miles away.

Next day, mechanic started the car, no problem. Fast idle, driving 30 minutes. He said he could not diagnose unless the car would not start. I drove the car back home, suspicious of getting stranded on the road again. Took the following steps to try and locate problem.

Resolder relays and check electrical connections:

Resolder fuel pump relay over visible etching around lugs (fuel pump relay is located behind fuses in center console on separate relay panel. Fuel pump relay on 700 series is the white rectangular one on left side of relay panel, second row when looking from back of car toward the front. Note: date stamped on fuel pump relay indicated it was original to the car.

Resolder radio suppression relay. Radio suppression relay on 700 series turbo engine is the black rectangular one located in the left side of engine bay, mounted on front strut housing.

Started car, idled for 5 minutes and drove for about three miles. Car died and would not start. Let sit for 15 minutes, and it started, drove home.

Started car, idled, ran 20 minutes in driveway, and died. Restarted immediately, idled another 20 minutes, died.

Restarted drove back and forth in driveway, car died.

Restarted again, idled 5 minutes, then died.

Car would not restart. Installed new fuel pump relay; no start

Let sit for 30 minutes. Still no restart.

Waited another 30 minutes. NO START.

Took following steps to try and diagnose problem.

Wiggle key in ignition switch while trying to start, to see if there might be a bad connection or bad ground in ignition switch.

NO START

Remove and clean each fuse in the fuse panel with spray electronic cleaner and wipe with cloth.

NO START

Clean ground connections with electric spray cleaner and cloth at intake manifold, on firewall, and electric connections at Ignition Module, Air Mass Meter, Coil, Battery, Overpressure Switch, Ignition Control Unit, Ballast Resistor near Ignition Module.

NO START

Check vacuum hoses, for cracks. Small crack near end of one small hose. Disconnect hose, cut 1/2 inch off end of hose, reconnect. Blow though each visible hose and check for leaks. No air leaks.

NO START

Mark distributor and rear of engine where the two meet, in order to keep same timing as set. Remove Distributor and check visually – Clean Contact Points on Distributor Cap and Rotor which were burnt. Clean connector at plastic Hall Effect Sensor connector which was intact, but slightly oily. Note, Distributor O-Rings need to be replaced. Reconnect Distributor and Hall Sensor wire.

Test fuel relay and fuel pumps:

There are 2 yellow/black wires plugged into a white plastic connector located above the brake pedal in passenger compartment. These 2 yellow/black wires are connected (via the white plastic connector) to 2 black wires going to the ignition control unit, which is located above the white plastic connector.

Connect one end of a foot-long test wire onto the yellow/black wire which is nearest the rounded part of its white plastic connector). Turn ignition key on. Connect the other end of the foot-long test wire to a known ground. Heard the main fuel pump whirring on the undercarriage below the drivers seat. Heard the in-tank fuel pump whirring by removing the gas cap and listening to it. Both fuel pumps (front and rear) whirr.

This indicates that the fuel pumps both worked. Note, with wire connected to the black/yellow wire as described above, I believe this bypassed the fuel pump relay. Tried to restart with this wiring still connected, but no restart. Note: I understand that the fuel pumps are not designed to run long without the engine running, so don’t this test wire hooked up with the fuel pumps whirring for more than a few seconds while testing.

Waited another 30 minutes. No restart.

Disconnect Negative Battery Terminal

Unplugged Air Mass Meter

NO START

Reconnect Air Mass Meter and Battery Terminal

NO START

Disconnect Negative Battery Terminal

Unplug Air Mass Meter

Substitute known good Air Mass Meter

Reconnect wire to Air Mass Meter

Reconnect Negative Battery Terminal

NO START

Use remote starter:

Connect the black wire from remote starter (via alligator clip) to a small wire on the car, which is connected to the front of the car’s starter solenoid. (This small solenoid wire on the 760 has blue insulation on this wire). Connect the red remote wire (via alligator clip) from remote starter onto the Positive Terminal of the car’s Battery. Turn Ignition on with key. Press button on remote starter and crank the Engine. Be sure to turn the Ignition key off after each segment of testing.

Test for spark from Coil:

Pull Coil wire end from Distributor Cap. Place the end of the Coil wire 1/4 inch away from a known ground, such as a mounting stud of the front strut. Turn the Ignition on with key. Crank Engine with remote starter. See a blue spark in the plug?

NO SPARK.

Reconnect Coil wire back into Distributor.

Test Coil Primary Leads:

With Ignition key on, clip the ground wire of a 12 volt test light onto known good ground, such as a mounting stud of the front Strut. Touch the pointed end of the test light to one of the 2 small connectors on the Coil. Leaving the ground in place on the test light, touch the pointed end of the test light to the other small connector on the Coil.

The test light should shine brightly on each lead.

YES.

Keep the wires connected as in above paragraph. Connect the remote starter as described above. Turn on the Ignition with the key. With Ignition cranking, and the test light grounded, place the pointed end of the test light on the Negative Coil Lead, the test light should blink. Try connecting the test light into each of the 2 small leads in the Coil, one at a time. One lead should be solid with the Engine cranking, and the other should blink.

NO, EACH COIL LEAD STAYED LIT SOLID, NOT BLINKING.

Disconnect the test light from Coil.

Test for spark from Distributor to Spark Plug:

Pull wire from one spark plug and insert the wire end into a spare plug. Anchor the threads of the Spare Spark plug onto a ground, such as a Strut Mounting Stud (Note: use vice grips to anchor the spare Spark Plug to ground, since if there is not a good connection, my mechanic tells me that the spark could jump back and blow an Electronic Computer or Ignition Control Unit).

Spread the Spark Plug gap to about 1/4 inch to ease viewing of spark. If not still connected, connect the remote starter as described above. Turn Ignition on with key. Crank Engine with the remote starter.

NO SPARK.

Reconnect Spark Plug wire to original Spark Plug in Engine.

Check Ignition Module:

Ignition Module is attached to the front inside left fender.

Loosen wire clip on Ignition Module. Pull wire cluster out of Ignition Module. Clean terminals on wire end and Ignition Module end. Clean off any corrosion (may look white and powdery) from back of Ignition Module and from its Heat Sink Plate, which is attached to inside of fender, between the fender and the Ignition Module. Reconnect wire cluster to Ignition Module.

Retest the Coil for spark and retest Primary Coil Leads as described above.

Substitute Ignition Module (Number 227 100 124)

($80 from independent, who knows how much from dealer, or $5 used;

Installed known good ignition module, cleaned off heat sink plate.

NO START

Test electricity to Fuel Injector:

Disconnect one of the Injector wires, by removing the small clip from the injector base, near intake manifold. Clip the 12 volt test light wire to ground and touch pointed end of the test light to one of the injector wires. Key on, crank Engine with remote starter. With key still on and timing light grounded, touch pointed end of timing light onto other Injector wire and crank engine. Does the test light blink while the Engine cranks?

NO, STAYS SOLID ON EACH INJECTOR WIRE.

Note: I heard that when cranking engine and it won’t start, see if tach needle moves a little. If not, check Hall Effect Sensor. I believe the tach needle moved a VERY little.

Note from my mechanic when car would not start initially: "A test light on the Coil shows a solid (not pulsing) 12V on both primary terminals while cranking, and a Noid Light (special light with injector connectors, substituted for an injector) shows no injector squirt. A component common to *both* systems will be the key. None of the wirig diagrams we have is specific enough to show me, but I'm looking towards Hall Effect, or something providing RPM info to the computer. Without knowing the engine is turning, the Computer will send no spark or injector signal."

Remove distributor cap, check to see that the Rotor turns, which means that the Timing Belt is OK.

Substitute a known good Distributor which contains a known good Hall Effect Sensor.

Bingo. Engine starts!

*Original Hall Effect NG*

Car is back on the road!

Checklist complete.