96 850 not starting sometimes

DeathRex · Post by **DeathRex** » 17 Jun 2019, 18:42

I have a 1996 850 that the motor will turn over, all the correct dash light light up, but it won't fire. It's happened 4 times in 3 years, but twice yesterday. I thought it might be the park sensor, but I moved the gear lever from park to neutral and back several times and that did nothing. Any ideas?

tardcart · Post by **tardcart** » 17 Jun 2019, 18:59

the park-neutral- park switch only disables the starter as far as starting goes. so if its turning over, its fuel or spark.( compression so unlikely will leave it out) fuel pump or FP relay is high on list.

Post by **Clemens** » 18 Jun 2019, 05:38

After truning over, remove a spark plug and see if it is wet or smells like fuel. If so, you might have no spark. Otherwise not enough fuel.
There is also a good chance that it is the engine coolant temp sensor. If it is faulty you might get a no start situation.

Post by **SonicAdventure** » 18 Jun 2019, 07:57

Interesting that you post this as I am currently dealing with this issue in my 1996 850. Things I have tried thus far to chase the problem down include new ignition, and replacing the fuel pump relay and the idle air control valve. Unfortunately, it is still occurring randomly. For instance, I can start the car, drive it 20-30 mins, cut off the motor and then 10 mins later try to start it and it wont start. If I wait 20-30 mins or a few hours, it will start up again on the first try.

My mechanic confirmed that when it was in a no-start state, there was no spark, but he was perplexed as to why spark would be present later in the day when he successfully started the car again.

Post by **erikv11** » 18 Jun 2019, 08:15

DeathRex wrote: 17 Jun 2019, 18:42 I have a 1996 850 that the motor will turn over, all the correct dash light light up, but it won't fire. It's happened 4 times in 3 years, but twice yesterday. I thought it might be the park sensor, but I moved the gear lever from park to neutral and back several times and that did nothing. Any ideas?

I agree that the first thing to suspect is a bad fuel pump relay, jumper the relay the next time it crops up. If that doesn't luckily solve it the next step is to determine whether or not there is spark. Bad ECT does not kill spark.

SonicAdventure wrote: 18 Jun 2019, 07:57 Interesting that you post this as I am currently dealing with this issue in my 1996 850. Things I have tried thus far to chase the problem down include new ignition, and replacing the fuel pump relay and the idle air control valve. Unfortunately, it is still occurring randomly. For instance, I can start the car, drive it 20-30 mins, cut off the motor and then 10 mins later try to start it and it wont start. If I wait 20-30 mins or a few hours, it will start up again on the first try.

My mechanic confirmed that when it was in a no-start state, there was no spark, but he was perplexed as to why spark would be present later in the day when he successfully started the car again.

Think of which sensors kill spark when bad ... I'd grab spare cam and crank sensors from the junkyard and swap them in one art a time, see if either cures it. Cam sensor failure is common for an aging 850, although they usually give up all at once not intermittently.

Post by **SonicAdventure** » 18 Jun 2019, 08:29

SonicAdventure wrote: 18 Jun 2019, 07:57 Interesting that you post this as I am currently dealing with this issue in my 1996 850. Things I have tried thus far to chase the problem down include new ignition, and replacing the fuel pump relay and the idle air control valve. Unfortunately, it is still occurring randomly. For instance, I can start the car, drive it 20-30 mins, cut off the motor and then 10 mins later try to start it and it wont start. If I wait 20-30 mins or a few hours, it will start up again on the first try.

My mechanic confirmed that when it was in a no-start state, there was no spark, but he was perplexed as to why spark would be present later in the day when he successfully started the car again.

Think of which sensors kill spark when bad ... I'd grab spare cam and crank sensors from the junkyard and swap them in one art a time, see if either cures it. Cam sensor failure is common for an aging 850, although they usually give up all at once not intermittently.
[/quote]

Erik, referencing my other post about my V70, would the cam and crank sensors from that car (both base model engines) work in an 850? If not, what year range 850 would I have to pull them from? I'm thinking it would have to be 95-97, but I'm not sure.

DeathRex · Post by **DeathRex** » 18 Jun 2019, 10:25

So far it has started every time. I pulled the fuel pump relay, and took it apart, there is a circuit board in there. The relay contacts looked excellent, but there were three, looked like cold solder joints, on the PCB. You wouldn't think the joints would be bad because it's a dual sided board and the holes are plated through. But when I put some solder on, it just kinda pulled away from the component. I sucked the solder out and resoldered it. I have the back seat down so I can hear the fuel pump when I start it.
Is there an ignition relay?

Post by **erikv11** » 18 Jun 2019, 18:50

SonicAdventure wrote: 18 Jun 2019, 08:29
SonicAdventure wrote: 18 Jun 2019, 07:57 Interesting that you post this as I am currently dealing with this issue in my 1996 850. Things I have tried thus far to chase the problem down include new ignition, and replacing the fuel pump relay and the idle air control valve. Unfortunately, it is still occurring randomly. For instance, I can start the car, drive it 20-30 mins, cut off the motor and then 10 mins later try to start it and it wont start. If I wait 20-30 mins or a few hours, it will start up again on the first try.

My mechanic confirmed that when it was in a no-start state, there was no spark, but he was perplexed as to why spark would be present later in the day when he successfully started the car again.
Think of which sensors kill spark when bad ... I'd grab spare cam and crank sensors from the junkyard and swap them in one art a time, see if either cures it. Cam sensor failure is common for an aging 850, although they usually give up all at once not intermittently.

Erik, referencing my other post about my V70, would the cam and crank sensors from that car (both base model engines) work in an 850? If not, what year range 850 would I have to pull them from? I'm thinking it would have to be 95-97, but I'm not sure.

Absolutely, definitely grab them from the 98 they will work in your 96.

DeathRex · Post by **DeathRex** » 19 Jun 2019, 11:53

Well Liam took it to the store, about 2 miles away, and it wouldn't start when he went to leave the store, and he said the fuel pump is working and it's full of gas. He didn't check for fuel pressure, but it sounds like spark.

shegarty · Post by **shegarty** » 21 Jun 2019, 06:50

+1 on the cam and crank sensors. When they go bad the ECM will inhibit spark to prevent firing because it does not know where in the cycle the engine is. As we are talking about electrical components this will be worse or happen more frequently during temperature extremes (ie. after a run and the engine bay is hot) and then disappear once cooled off again.