My 1990 760 Turbo will not start. It is about 20 degrees F here. I have verified that I have spark and broke my fuel line and have fuel flow. I checked the fuel pressure regulator, it was not leaking at the vaccum port.

Any idea what should come next?

Thanks,
Hawk

It runs!!!!!!!

Believe it or not I changed out the Bosch Platinum spark plugs to new NKG and it started immediately. They were carboned up pretty bad and guess they weren't sparking.

I understand Bosch Platinums are not the best choice for these cars.

I learned a lot about the car in the process.

Thanks to everyone for your help.

Hawk

Go to www.stepbystepvolvo.com for free guide to 740 no-starts. The in-tank pump will still deliver fuel for the fuel test but, if the main fuel pump is dead, the engine will not start.

Simple RSR test - pull the relay, jump the two fattest wires in the plug, and try to start. If the car starts, the relay needs replacing.

Another possibility - several years ago, my wife's 740 had spark, fuel flow at the rail, and firing injectors, and still wouldn't start. Turned out to be the main fuel pump - it was functioning enough to flow fuel, but without enough pressure to deliver through the injectors. What probably caused the main pump to fail was the previous failure of the in tank pump.

If the RSR checks out, try spraying some starter fluid into one of the vacuum ports in the throttle body. If the car fires then dies in a second or three, suspect the pumps.

Thanks to each of you for your responses. We have 2 240 wagons to drive (that run) and its in the teens here. I will try all of these on Saturday and hope it's warmer.

I guess I am just too old to work on a car, in the dark, in 15 degree weather, when I have another one that running.

I going to replace the plugs on the outside chance that they are fouled and not firing. I have extra RS Replays that I can swap but the wiring harness connections are getting a little broken down. The crank sensor was replaced about 5 years ago. I think the fuel pumps are not supposed to run unless the computer is getting a signal that spark should be occurring. I will see if I have fuel flow during cranking.

Thanks to all,
Hawk

Have a friend crank the car and feel the air coming from the exhaust. If it's unburned fuel, you can look into spark issues, if it's dry and smells like air and NOT gas, look further into injection.

You might also try starting it with the AMM unplugged, just for kicks. This will throw a check engine light though. It can be cleared.

good luck,
Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

Yes, RSR. It is possible to have spark, fuel pressure and air, but no start in a 700. The injectors are not firing.

You can check the radio supression relay by disconnecting the injector plugs and turning on the ignition. You should have 12 volts to ground on one plug pin and zero on the other for every injector.

The +12V and 0 volts at the injectors is not exactly right,maybe misleading.

The RSR delivers a constant Plus 12VDC to each injector when it is happy.
The injectors operate with a ground return to the battery via ECU switching.
(You can measure 0 volts without a ground return)

Look up noid light in the FAQs, that might be the easiest way to confirm
that the injectors are getting powered OK.

Nothing missleading about it. If you check each injector plug with the ignition turned on you should find 12 volts to ground on one pin and zero on the other.

One of the injector pins has a constant +12VDC via the RSR
the other pin has zero volts as you say, but that isn't the whole story
you need a ground return to the battery via the ECU
You can see zero volts and have no ground switching.
The injectors are enabled (providing the Plus 12VDC is there)
with ground return switching by the ECU.

Maybe someone will put their voltmeter ground on the block and see
+12VDC and zero volts, but the ground leg needed is via the ECU.

You need to be carefull to measure at both injector connector pins

Thats why a noid light is nice. or just a spare injector connector from a junker
to make it easy to hook up your meter to the injector harness connector.

We're just checking to be sure the RSR is supplying 12 volts. That's it!!

OK if you see a constant +12vdc at one of the injector wires then the RSR is OK
you still may have dead injectors since you need the switched ground return from
the ECU.

It helps to have a decent multimeter and a greenbook wiring diagram to
handle the electrical issues.

check your crank sensor on top of the bell housing
fuel pump relay.........be careful the relay board is located passenger side left leg behind the left leg panel. many of those relays are not removable...on the 760 check the FAQ first
ignition control module
cold start injector under the manifold

Check the functionality of your Radio Suppression Relay and the Fuel Pump Relay.
See FAQ's, both are common causes of no-starts.