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2002 9-5 Aero - Intermittent No Start - Fuel Pump? CPS Sensor?

694 Views 13 Replies 5 Participants Last post by  horsehockey
I have a 2002 9-5 Aero wagon with 97,000 mi. For the last few of weeks I've been experiencing an intermittent no start. The engine will still turn over and the battery is strong. There are no check engine lights.

At first I thought it was DIC related. Being a good Saab owner, I carry a spare in the trunk. I swapped DICs but I'm still experiencing the problem. The plugs are also pretty new NGKs that I put in about 6 months ago.

I use the car as a daily driver and it happens 1-2 times a week.

Any thoughts on what this might be? I'm thinking fuel system/fuel pump or maybe the crank shaft position sensor.

Is there a good way to test for either of these things, or would I have to swap the part to know for sure?
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'85 900; '10 9-3 ; '04 9-5; ex- 9000aero, 06' 9-3
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Does it happen when car is warm, or cold? any patterns observable as to when the no start happens?

A few quick notes, but not exhaustive:
-CPS generally gets temperamental when engine is hot, ..but not always, --An easy way to observe if it may be the CPS is watch to see if the tach bounces a bit when cranking...

--Fuel pump can be heard "priming" if you turn the key to start, but not ignition. Generally if you hear the pump buzz and prime you can expect the fuel pump is ok.

I would start with these observations. cold or hot engine, fuel pump priming noise, watch tach during the no starts.

Also, if it no starts, when does it start up next? soon, or much later? do you do anything to get it started again? is it no start on first two cranks but then a start on the third?

Lastly, are you located somewhere where temps have changed significantly from winter to spring?

I dont mean to barrage you with questions! :). just this info might lead to the cause :)
hope this helps and that some more info can be gleaned from these observations that will help quickly diagnose

good luck!
 

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1997 900 SE Turbo, 2002 9-5 Aero Wagon
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Discussion Starter · #3 ·
Does it happen when car is warm, or cold? any patterns observable as to when the no start happens?

A few quick notes, but not exhaustive:
-CPS generally gets temperamental when engine is hot, ..but not always, --An easy way to observe if it may be the CPS is watch to see if the tach bounces a bit when cranking...

--Fuel pump can be heard "priming" if you turn the key to start, but not ignition. Generally if you hear the pump buzz and prime you can expect the fuel pump is ok.

I would start with these observations. cold or hot engine, fuel pump priming noise, watch tach during the no starts.

Also, if it no starts, when does it start up next? soon, or much later? do you do anything to get it started again? is it no start on first two cranks but then a start on the third?

Lastly, are you located somewhere where temps have changed significantly from winter to spring?

hope this helps and that some more info can be gleaned from these observations that will help quickly diagnose

good luck!
Thanks this a helpful rubric. I'll look out for the CPS tach symptom and listen for the fuel pump.

Every time except for once, it's happened to my wife while I wasn't there. Usually I'll show up about 20-30 minutes later and it will start.

The one time that it happened to me was the first time we had the problem. The engine was warm but not hot (~60min since it had been driven). I cranked 4-5 times before deciding to swap the DIC. That took me about 10 minutes. I tried restarting, and on the the second time cranking after swapping DICs, it started.

I'm in Tennessee, so we don't have that much fluctuation in temperature. It's been pretty moderate for the last couple months.

Thanks!
 

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I'm sure others with more knowledge than me will help out, but good to know these answers.

You might want to take a look at the throttle body for signs of oil from the intake pipe...cant hurt to just do a quick look...

again fingers crossed something apparent shows up
 

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1997 900 SE Turbo, 2002 9-5 Aero Wagon
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Discussion Starter · #6 ·
I'm sure others with more knowledge than me will help out, but good to know these answers.

You might want to take a look at the throttle body for signs of oil from the intake pipe...cant hurt to just do a quick look...

again fingers crossed something apparent shows up
Roger. Can you connect the dots for me? What would finding oil in the intake pipe indicate?

Incidentally, I replaced the throttle body in the last year, so that's all new OEM parts.
 

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Roger. Can you connect the dots for me? What would finding oil in the intake pipe indicate?

Incidentally, I replaced the throttle body in the last year, so that's all new OEM parts.
Intermittent and or weird no starts issues, when fuel pressure is good and CPS is good, might be TB issue? Thats my thought.

It may not be helpful at all in your case...but just verifying nothing weird at the TB can be useful...especially if CPS and fuel check out. (Doubtful you will have oil at TB since you have the more robust hpt TD04 turbo, but oil thrown from loose seal turbo might make TB act weird)

...I had a similar issue past year, but its not at all apples to apples, since my issue was a cold start then die immediately, then start right up fine situation that ended up being due to oil from a bad lpt garret turbo that wasnt showing any other obvious signs of failure...I chased a lot of possible avenues before just looking at the TB and seeing oil there...)
 

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1997 900 SE Turbo, 2002 9-5 Aero Wagon
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Discussion Starter · #8 ·
Intermittent and or weird no starts issues, when fuel pressure is good and CPS is good, might be TB issue? Thats my thought.

It may not be helpful at all in your case...but just verifying nothing weird at the TB can be useful...especially if CPS and fuel check out. (Doubtful you will have oil at TB since you have the more robust hpt TD04 turbo, but oil thrown from loose seal turbo might make TB act weird)

...I had a similar issue past year, but its not at all apples to apples, since my issue was a cold start then die immediately, then start right up fine situation that ended up being due to oil from a bad lpt garret turbo that wasnt showing any other obvious signs of failure...I chased a lot of possible avenues before just looking at the TB and seeing oil there...)
Gotcha. That makes sense. I know what you mean about chasing an unusual problem. That's good knowledge to tuck away for the future. My gut is telling me that CPS sensor or less likely fuel pump is the culprit.
 

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1997 900 SE Turbo, 2002 9-5 Aero Wagon
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Discussion Starter · #11 ·
Well, my wife tried starting it and reported that there is no movement on the tach needle while cranking. Sounds like it’s a CPS. I’ll swap it out with a Bosch and report back on what happens.
 

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Let us know what you observe on the tachometer while cranking. If it remains dead still, then you have a dead CPS.
If the tack needle jiggles a little bit while cranking, CPS is good.
My RPM meter goes up a little bit, from below "0" to "0" after a few cranks and falls back below "0"when I stop cracking. No dancing. Is this a dead or alive CPS?
 
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