With an 850 no start how do you rule out the fuel injector relay as the problem? No CEL codes. Thanks.

FCP Groton has the relay your wondering about for 23.00 dollars. It's in the engine compartment above the radiator. Might be a cheap way to rule that out.

The injector relay would be last on my list of things to check. Fuel pump relay, fuel pump, cam position sensor, MAF/AMM (just unplug it when engine is not running, do not plug it back in with the engine running), low compression on all cylinders (add a tablespoon of oil to each cylinder), and the list goes on.

Klaus
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Proud owner of a 220S. If I had more room, I would have more Volvos.

How many miles on the car? Has the fuel pump ever been replaced?

Every 850 driver should have a spare set of relays (ebay) and a MAF sensor and Cam Sensor in the glove box. You can fix 90% of issues with these items. Some people here have had problems with the fuel pump relay.........do you have fuel pressure on the rail? You can pull the guard back that protects the fuel injectors (hold the plate and pull it back towards you.....then you can hook up a line voltage indicator on the wires to see if the injector is firing.

My guess is the fuel pump died. Depending on how cold it is where you live, try some dry gas.

If you pop a clip off the injector plug to check voltage, be careful with the retaining clip- if it flies off, you might not find it again. put an alligator clip on it or something.

Thanks Klaus and DG. My son is away at college in Salt Lake City and just wouldn't start last week after running great for months except for a roaming idle. We've only owned the wagon for about 9 months. It has about 220K but compression on all the cylinders when we bought were all about 190 plus. I don't know that the fuel pump or fuel pump relay has ever been changed so we'll check them out as you suggested. Thanks again for the advice.

If the car had a roaming idle, that could be a Mass Air Flow meter problem or it could be that the plastic intake hose from the air cleaner to the throttle body has a hole in it or is cracked. Mine developed a crack a long time ago and the car would die every time I got off the highway and idled badly. Something cheap to check out.