I have been having similar starting difficulties with my Volvo as this thread:https://volvoforums.com/forum/volvo-...p-62194/page2/

I have check spark on all 5 cylinders, compression on all 5, fuel injection, and the timing belt. All are working.

I still need to check timing and the crank position sensor.

Before reading the above post I was down to two options : bad crank position censor or bad ECU.

The car had been sitting outside, undriven, for about a month before I drove it home and it resoundingly 'died'.

Are there any ways to quantitatively check the fuel in the gas tank?

Thank you in advance for any advice and/or time you provide. I am very much appreciate it

 

if you think it might be bad gas, then try to fire it up using a little spray of starting fluid. If it fires up then dies, then you know it's something to do with the gas. But one month old gas shouldn't be the cause of it not starting, unless it was bad to begin with.

If you've got spark, fuel and compression at the cylinders then the only thing that should be keeping it from firing is the timing of the spark. Well, or you're not getting air in there.

 

Thanks so much for your reply.

I did nab some starter fluid and tried it out - no luck.

Because I like to throw money at things to solve my problems (X.X) I replaced the Crank Position Sensor - no luck.

Still have spark - compression - and fuel. I keep leaning towards a busted ECU.

Since this is a 1998 can I simply swap it out or do I need to get the new unit coded and what not?

Not to familiar with that procedure - so if there is any other item I can check prior to replacing the computer I would appreciate it

 

I would try to find a noid light and check for injector pulse.
If you have spark and fuel the pulse might be missing.

 

did you check the fuse to the fuel pump ?. Spray on some contact cleaner and see if this works

 

You need 3 (4 things) for ignition, fuel, spark, and air. If compression is good, fuel is spraying, spark it there (means the cam shaft sensor is good), then your problem is likely air. Do you have a CEL?

 

Thank you all - some updates:

I tested the injectors with a noid light and am seeing a pulse on all five injectors. To triple check that they were firing I removed the spark plugs after turning the engine over and it smelled like fuel.

I have checked the Fuel pump fuse and relay - both are working. If I had made a mistake though - wouldnt the starter fluid test have started the car?

When I turn the key to the 'On' position all my warning lights engage - but only the SRS one turns off. This includes my CEL staying lit. From what I have read this is usually a sign of a bad ECU.

Furthermore, when I plugged in my OBD-II sensor and tried to read the engine data - I receive a failure to communicate message which after trying to connect again appears to go away - thus appearing to connect to the ECU. To be honest though, the signals I read from the OBD after this reconnection appear to be default settings?

Even more back story - when replacing the serpentine belt - I unkowningly removed the ECU without allowing it to power down. The car started up and ran a few times after that - but nothing since then.

I have not checked the O2 sensor or the IAT sensor - nor would I know how.

Thank you all again.

 

I would try to find a cheap used ECU to try.

 

Called up the volvo dealership and confirmed that for a 1998 I can put a used ECU in the car w/o programming.

Found a used ECU from a friend who runs a local junk yard and tried it out - no change.

My friend also gave me the pin out diagram for the ECU connections and I checked the power level at PIN #27 (main power relay) and didnt get 12.5+V. My question is would all the dash lights turn on if the ECU was not receiving power?

Now it is looking like some electrical wiring problem - which is rather intimidating - so I have pretty much determined to sell her...

 

Well if you have spark,injector pulse,fuel and compression it should run.

Maybe check timing now to make sure it did not jump time. It has to be something pretty simple if you have all elements for it to run.

 

Just an update:

Ended up taking it to a mechanic and he got it to start. The issue was two fold - a midly worn distributor rotor and a locked up ac compressor clutch.

He replaced the rotor and took off the serpentine belt and she came to life. Now on to an ac compressor replacement - oh why volvo did you bury your ac compressor

 

Names roger can u message me to 5054265815 I am going thro the same situation but came to a holt if anyone can hlp plz and ty

 

Hi Roger, there are a lot of no start threads on here, every month or two. A 1998 S70 is exactly like an 850, so all the 850 no start threads would also apply.

Do you have spark? Fuel pressure?

 

Ty on the info and ya I have spark and gas pressure I'm going down the line on what can be the problem now going to get the security board under the dash to see if that us giving me the problem but I'll keep updated as I go about doing it