1996 850 Turbo, wont start but has fuel and spark

[idigvolvos]

Would a faulty TDC sensor cause a car to not start but still have spark? Same with a camshaft position sensor.

[Klausc]

All of this is getting to me. A faulty CPS will cause a no spark, no sure about the crank position sensor.

You indicated that you had a rough idle for a year or so and nothing was done. When you started the car and it immediately died, you may have caused "lawn mower syndrome". Look it up. Charge your battery to a full charge as 11V will produce a weak spark condition from the coil.

My guess is that you have a leaky injector, or a very dirty one, that is causing the poor idle and running rich. Unless you are using non copper plugs and they have been in the car for over 10K miles.

[rspi]

Over 2 weeks ago I posted the video that explains that you need 5 things for the car to start:

1. Fuel, not only at the rail, but actually spraying in the cylinders. If you spray starter fluid in the intake through the throttle body, and the car starts for a few seconds, there is a good chance that the fuel injector relay is bad and not telling the injectors to actually spray fuel, even though you have proper fuel pressure in the rail. Is fuel getting into the cylinders? Are the spark plugs wet with fuel?

2. Air, if your MAF or some other air intake problem exist the car will not start. Do you have a CEL? Did you have the car scanned? These questions went unanswered. Are you ignoring them?

3. Timing: Has that been checked? Is the cam turning?

4. Spark: That is the only thing we do know you have. Although weak.

5. Compression: For the 4th time, what are the compression numbers?

If you do not reply that you have verified these 5 things, no one can really properly help you. We can keep tossing things out there but until you verify the top 5, you really are wasting your time.

[northernlights]

Would a faulty TDC sensor cause a car to not start but still have spark? Same with a camshaft position sensor.

No cam sensor or crank sensor means no spark and no fuel. The books say it won't start or run without the crank sensor and it won't start without a cam sensor.

Volvo didn't want to have any BBQ's is they weren't sure the engine was turning, unlike the domestic cars which will run with an amazing lack of input signals.

You can have rail pressure and still no fuel to the injectors if the ECU doesn't think the engine is turning. The fuel pump will still prime with 'key-on' but the injectors don't fire without the above signals. But, it won't spark, so I think something else is going on if you see a spark.

[idigvolvos]

The car will not start with starter fluid and as I stated in my original post the cam is turning. I am not ignoring questions, just trying to go through one thing at a time with my very minimal experience (and not much time). I appreciate all the comments and help and am trying to address them. No, I did not have the car scanned, I do not have access to a scanner.

The spark plugs, battery and cap and rotor were all just replaced last week.

Thanks, I will look up "lawn mower syndrome".

[rspi]

[Klausc]

RSPI, I really enjoy your videos! The Volvo community thanks you.

As for the lawn mower syndrome, adding oil to each cylinder is less messy if you dip a drinking straw into the bottle of oil, cover the end with a finger and use the long straw to deliver the oil to the spark plug hole. About 2 inches of oil in the straw is ideal.

Also, cranking the starter with the gas pedal on the floor will tell the ECM to turn off the injectors. Once the engne starts to sputter, release the gas pedal.

Some have found that cranking until the oil light goes out, waiting 10-15 minutes to let the starter motor cool down, and repeating the process works quite well. No need to burn out a starter motor.

The OP does have another problem: something caused the engine to stop running. What that is we may never know. He does not have access to a scanner.

[rspi]

It is tough that it does not start with starter fluid. I have actually never had to try that, not sure how much it takes, but having fuel and spark, it can be tough to track down.

[jacobharding]

Did you checked the master fuel injection relay?

It's located at cooling fan carrier,it's big grey relay,usually stamped Made in Hungary on it.

Don't know if you have fixed this or not yet but just so you don't go crazy for 8 months and needlessly throw a bunch of money at the car, like I did, definitely check this relay. The relay itself may be good but check the connectors at the harness for corrosion and looseness. My relay turned out to be good but the connector was all ate up.

[jacobharding]

Actually now that I think about it mine would start and run for a few seconds and then cut off. I am thinking maybe the initial prime gets the engine started so this relay is not necessary to the car starting...maybe?...(Initial priming just pressurizes the rail and I believe this relay actually controls injector firing/timing so i'm not really certain on this unless the cam sensor controls it at initial startup and then it is handed over to the relay.) I do not have a running 850 to test this theory but maybe someone out there with an 850 (Misha?) would be so kind as to unplug the main FI relay and try starting the car. If it starts and then shuts down this would probably rule it out as being your issue.