[jeroendo2]

Hi all,

My Saab 9-5 lost power during a mile then stalled. What I have done or know is;
- it now cranks but won't start
-swapped DI cassette, no help
-pushed fuel rail valve, no pressure
-had previously "check engine" warnings once in a while, and went off.
-sparkplugs visually look ok.
-sprayed brake cleaner in throttle body then cranked; no result, assuming also no spark.
- see vid; RPM meter moves but I'm not convinced CPS is workingRPM meter

- I read I can test CPS by reading ohm between 2 pins. I assume after disconnecting the connector? Do I need to remove CPS to test it or can leave it where it is?
-any other advice, apart from reading the computer?

Saab 9-5 2002 2.0t automatic

 

[jvanabra]

Correct resistance of the sensor is 200-900 ohm. You do not need to remove the sensor to test. Also, be aware the sensor can fail and still show the correct resistance. You are probably best off testing for spark and fuel pressure. If you have either one, the CPS is fine.

 

[bob3000]

Correct resistance of the sensor is 200-900 ohm. You do not need to remove the sensor to test.

I'd add, if you are inclined to go to the effort of crawling up in there then just change the CPS with a Bosch and be done with it.

Fifty bucks well spent.

 

[Windsor]

No effective way to test CPS other than replace it. Can you hear the fuel pump buzz under the back seat when you turn the key to the on position? Do you get fuel pressure at the SchrAdler valve on the fuel rail?

 

[jeroendo2]

No effective way to test CPS other than replace it. Can you hear the fuel pump buzz under the back seat when you turn the key to the on position? Do you get fuel pressure at the SchrAdler valve on the fuel rail?

Hi, no pressure at fuel rail valve. Will check if I hear it under the back seat. If I hear it it means pump works, and likely default CPS won't let pressure in rail ?

 

[jvanabra]

After the car has been sitting a while, when you first turn the key the pump runs for two seconds and stops. It will not run again until there is a signal from the CPS.. so if the pump runs while cranking, you know the CPS is working.

 

[Windsor]

Just to clarify what Jvanabra said, every time you turn the key, you will hear the pump prime and then stop

 

[jeroendo2]

Update: the fuel pump under rear seat zooms for a couple of seconds when turning the ignition on ( not cranking) However still no fuel at fuel rail valve. As I thought that it would run if I spray break cleaner in inlet and it didn't do anything I am getting confused, Did I saw someone writing; "if there is no fuel then automatically there is no spark"?
note; i measured 900 ohms at CPS that is a first good sign but no guarantee I have already understood. Tomorrow will swap spare key which has no alarm function with original key.
So main question; Does Saab 9-5 give no spark if no fuel?

 

[jvanabra]

Just to clarify what Jvanabra said, every time you turn the key, you will hear the pump prime and then stop

That is not accurate. The pump only primes once every X hundred seconds. I don't know what that is, but I think it's 5 or 10 minutes. If you keep turning the key off and on, it will only prime once.

 

[jvanabra]

So main question; Does Saab 9-5 give no spark if no fuel?

That's not exactly right. If there is no CPS signal, the ECM will not run the pump and will not run the DIC.

That is not to say if the DIC fails the fuel pump doesn't run.

If the pump is priming, you should have fuel at the fuel rail... if you don't, the pump is suspect. The next test is to get a fuel pressure gauge, run the fuel pump manually (jumper the fuse), and see if you have correct pressure.

Brake cleaner probably will not start a cold engine - use carb cleaner or starter fluid.

 

[jeroendo2]

That is not accurate. The pump only primes once every X hundred seconds. I don't know what that is, but I think it's 5 or 10 minutes. If you keep turning the key off and on, it will only prime once.

Should the fueling valve only spray strongly when cranking, or without cranking, just ignition on, is enough?

 

[jvanabra]

What you are suggesting is not a good test. You really can't understand what is happening without a fuel pressure gauge.

If the car has been sitting for a little while, you turn the key, the pump runs for about two seconds, and then you IMMEDIATELY depressed the valve on the fuel rail you should get a spray of fuel. But, that only happens if everything is working correctly - fuel pressure regulator, check valves, etc. - and there is no certainty that's true.

I would really encourage you to buy, rent, or borrow a fuel pressure gauge. They are typically not expensive.

If you are sure you can't get a gauge, then this is what I would recommend:

1. After the car has been sitting a while, turn the key and let the pump prime for 2 seconds
2. Depress the valve on the fuel rail and release any pressure that's built up
3. Crank the car over for 5-10 seconds
4. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump and CPS are probably working
If no, then either the pump or CPS are not working

Then,

1. After the car has been sitting a while, depress the valve on the fuel rail and release any pressure that's built up
2. Use a jumper wire to run the fuel pump directly from the fuse box for 5-10 seconds
3. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump is working
If no, then the pump is not working

I DO NOT recommend doing this. Releasing pressurized fuel into the atmosphere is a good way to start a fire. You should use a fuel pressure gauge. Continuing without one is dangerous.

 

[bob3000]

2. Use a jumper wire to run the fuel pump directly from the fuse box for 5-10 seconds

Can you elaborate on this? I've never heard of that, it would be handy to know how.

 

[jvanabra]

I use a 10' piece of 16ga wire with an alligator clip on one end and a .205" quick disconnect on the other. The clip goes on the battery, the quick disconnect goes into the fuse socket... The pump will run as long as the two are connected.

 

[jvanabra]

... if you have Tech 2 you can just do "fuel pump activation" but honestly the jumper is faster.

 

[bob3000]

... if you have Tech 2 you can just do "fuel pump activation" but honestly the jumper is faster.

I'm currently shopping for a TECH2, Merry Christmas to me....a Roomba and a TECH2.

 

[jvanabra]

I never once regretted my Tech 2 purchase... I ended up giving the Roomba to a friend.

 

[Windsor]

That is not accurate. The pump only primes once every X hundred seconds. I don't know what that is, but I think it's 5 or 10 minutes. If you keep turning the key off and on, it will only prime once.

On all 4 of my Saabs the fuel pump always primes no matter how many times I turn the key.

going back to the issue at hand, a fuel pressure gauge is a must in confirming a fuel supply.

 

[jeroendo2]

What you are suggesting is not a good test. You really can't understand what is happening without a fuel pressure gauge.

If the car has been sitting for a little while, you turn the key, the pump runs for about two seconds, and then you IMMEDIATELY depressed the valve on the fuel rail you should get a spray of fuel. But, that only happens if everything is working correctly - fuel pressure regulator, check valves, etc. - and there is no certainty that's true.

I would really encourage you to buy, rent, or borrow a fuel pressure gauge. They are typically not expensive.

If you are sure you can't get a gauge, then this is what I would recommend:

1. After the car has been sitting a while, turn the key and let the pump prime for 2 seconds
2. Depress the valve on the fuel rail and release any pressure that's built up
3. Crank the car over for 5-10 seconds
4. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump and CPS are probably working
If no, then either the pump or CPS are not working

Then,

1. After the car has been sitting a while, depress the valve on the fuel rail and release any pressure that's built up
2. Use a jumper wire to run the fuel pump directly from the fuse box for 5-10 seconds
3. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump is working
If no, then the pump is not working

I DO NOT recommend doing this. Releasing pressurized fuel into the atmosphere is a good way to start a fire. You should use a fuel pressure gauge. Continuing without one is dangerous.

Thanks for your time and effort, I'll test tomorrow and give an update.

 

[jeroendo2]

What you are suggesting is not a good test. You really can't understand what is happening without a fuel pressure gauge.

If the car has been sitting for a little while, you turn the key, the pump runs for about two seconds, and then you IMMEDIATELY depressed the valve on the fuel rail you should get a spray of fuel. But, that only happens if everything is working correctly - fuel pressure regulator, check valves, etc. - and there is no certainty that's true.

I would really encourage you to buy, rent, or borrow a fuel pressure gauge. They are typically not expensive.

If you are sure you can't get a gauge, then this is what I would recommend:

1. After the car has been sitting a while, turn the key and let the pump prime for 2 seconds
2. Depress the valve on the fuel rail and release any pressure that's built up
3. Crank the car over for 5-10 seconds
4. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump and CPS are probably working
If no, then either the pump or CPS are not working

Then,

1. After the car has been sitting a while, depress the valve on the fuel rail and release any pressure that's built up
2. Use a jumper wire to run the fuel pump directly from the fuse box for 5-10 seconds
3. Depress the valve on the fuel rail and see if there is pressure

If yes, the pump is working
If no, then the pump is not working

I DO NOT recommend doing this. Releasing pressurized fuel into the atmosphere is a good way to start a fire. You should use a fuel pressure gauge. Continuing without one is dangerous.

Today a rainy day, wil check tomorrow, one thing got me curious; it seems you say if CPS doesn't work you won't get pressure at valve nor during the 2 seconds when pump starts up, nor when cracking, correct? Or would it be; with bad CPS ( and working pump) you get pressure at valve for the 2 seconds startup, when turning on the ignition, but then will fail to booster when cranking?EDIT: sorry I see jvanabra already mentioned, thnx