ok so my mom's 94 850 Turbo wont start i have ruled out the fuel pump. when i took out the #1 spark plug out to check for spark and it dose not. my first thought was to replace the ignition coil. i got one from a junk yard and that one doesn't work either. i thought some of you could help me to figure this out. thanks

 

Make sure you have adequate fuel pressure. Test it at the valve at the end of the fuel rail. As for the spark, check to see if you have 12V going to the coil, and also a good ground. Next, if you have a volt/ohm meter, meter out the coil wire to the distributor to make sure it is good. Next, pull the cap off the distributor cap and check the condition of the cap, rotor, and the distributor itself.

Keep us posted. If it still doesn't start you may be looking at a bad crank position sensor and/or camshaft position sensor

 

Since you don't have spark it's not that important but how did you rule out the fuel pump, what did you test ??

If you took the coil lead off at the distributor tower and put it close to ground and have no spark it's likely a sensor that's failed as the coil and module don't seem to go as often.

You might have a failed crankshaft or camshaft sensor.

 

i had my brother turn the key to (run) or the second position with the radio off i stuck my head in the trunk to listen for the fuel pump...it comes on so i know its working

 

so how do i test these sensors. i have a multi meter but I'm not sure where to put the probes to test the sensors?. and what should the readings be if they are still good?

i checked the distributor and everything there is working. no cracks in the cap and the o-rings are still soft and new. plus the points don't appear to have any carbon build up.

 

i figured out how to test the sensors and for the cam sensor i get 10.7 volts and a signal of 4.7 volts. i was told that i should be seeing battery power witch in my case is 11.9 volts and that the signal should be 5 volts. is what i am seeing acceptable or wrong.

 

THose values are pretty close.

One thing I forgot to mention is for you to check all the fuses with an ohm meter to be sure they are good. Especially the fuel pump fuse and anything that is related to the ECM.

You can also disconnect the battery cables and short them together for a bout a minute. In some cases this will reset the ECM

 

First I would like to thank all of the members for the tips.
Ignition coil is working, swapped it on the other volvo and started fine
Replaced plugs, wires, distributor and rotor starts but idles wildly up and down almost stalling out, but if I let it idle for a little it evens out. Now getting code for O2 sensor voltage low. What next?

 

You might want to clean out the Idle Air Control motor and check all the vacuum hoses to see if any are torn, ripped or loose and leaking.
Especially the 90 deg elbows under the intake and near the throttle body.
The diagram isn't the best, sorry.

 

i would also try unplugging your MAF and see if it evens out. could be a fairly large air leak. check your brake booster lines

 

On the brake booster, you could pull and plug the line to check to see if you have a torn diaphragm inside the brake booster assembly.

 

If you are still having idle issues, warm the car up and do a compression test. You may have a burnt valve lowering the compression in a cylinder or two.