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9-5 stopped, CPS? RPM moves though, how to test CPS

1633 Views 55 Replies 5 Participants Last post by  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
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Discussion Starter · #22 · (Edited)
You could have replaced the CPS numerous times by now, why are you reluctant to do so?

It's a relatively cheap part and a very easy job.
I am on an island, with no easily parts to get and the car is on the side of the road stranded, not at my house, and its raining :-( Besides that I have another car and trying to understand is a hobby too. The CPS has all signs of being well ( RPM moves, ohms correct) So with the question if it should build op fuelpressure at valve even if CPS is dead, if the answer is yes I know its the fuelpump, as for sure I don't have pressure there without cracking.
 

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Discussion Starter · #26 ·
Hi thanks for all advice, I realize I am not going the quickest road for some, I am not that much in a hurry, and in the end I will get my parts.
Today I 've put a test light on the fuse for fuel pump. It gets power when turning the ignition on, then goes off. Then when crancking it goes on again; CPS seems to do it's job. Then putted a 12v direct from battery to this fuse as one of you suggested; the pump is hearably working but when pushing the valve at rail right after doing that; still no pressure; So bad fuel pump or clogged filter. The only thing I don't get; why doesn't it fire up after spraying starting spray?
 

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Hi thanks for all advice, I realize I am not going the quickest road for some, I am not that much in a hurry, and in the end I will get my parts.
Today I 've put a test light on the fuse for fuel pump. It gets power when turning the ignition on, then goes off. Then when crancking it goes on again; CPS seems to do it's job. Then putted a 12v direct from battery to this fuse as one of you suggested; the pump is hearably working but when pushing the valve at rail right after doing that; still no pressure; So bad fuel pump or clogged filter. The only thing I don't get; why doesn't it fire up after spraying starting spray?
On the surface, this sounds like a failed fuel pump. However, as I mentioned before this is not conclusive. If the check valves on the fuel pump are not working it's definitely possible you would lose rail pressure before releasing the Schrader valve. If you have a fuel pressure gauge attached, while the pump is running, you will know for 100% certainty if you have fuel pressure.

An alternative approach, which I would also not recommend due to extreme fire risk, is to detach the return from the fuel rail (the smaller of the two tubes), slip some fuel-safe hose over the rail, and direct those hose into a container. If you crank the car and gas fills the container, the pump at least somewhat works. Of course, without a fuel pressure gauge you don't know if it's enough.

In any case, it sounds like the CPS is working. I would probably cross that off the list as a suspect. You seem adverse to buying tools, but connecting a noid light to a fuel injector connector would rule it out entirely.
 

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Discussion Starter · #33 · (Edited)
On the surface, this sounds like a failed fuel pump. However, as I mentioned before this is not conclusive. If the check valves on the fuel pump are not working it's definitely possible you would lose rail pressure before releasing the Schrader valve. If you have a fuel pressure gauge attached, while the pump is running, you will know for 100% certainty if you have fuel pressure.

An alternative approach, which I would also not recommend due to extreme fire risk, is to detach the return from the fuel rail (the smaller of the two tubes), slip some fuel-safe hose over the rail, and direct those hose into a container. If you crank the car and gas fills the container, the pump at least somewhat works. Of course, without a fuel pressure gauge you don't know if it's enough.

In any case, it sounds like the CPS is working. I would probably cross that off the list as a suspect. You seem adverse to buying tools, but connecting a noid light to a fuel injector connector would rule it out entirely.
Hi yes you are right, a fuel pressure gauge would be quicker, I'll start it tomorrow with a friend while I am depressing the valve to rule that out, thanks. checking out now noid light.
 

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Not trying to be an alarmist but….to me, it sounds like there’s something wrong internally. Cranking is uneven and could point to a problem with at least one cylinder. It could be a bent/stuck valve (or stuck lifter?). Or - gulp - a holed piston. I’d do a compression test.

I’d also suggest charging the battery since it’s cranking even slower than normal.
 

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Discussion Starter · #40 · (Edited)
UPDATE: i checked compression and it doesn't look good; see pics; 3 cilinders at 3 bars and one at almost 6 bars.
I have checked the return fuel line by taking the rubber hose away at tank; fuel coming out, not spraying miles away and checked fuel rail valve while cracking; quite some fuel coming out but again not spraying me all over. But I am afraid it doesn't matter if the engine is done we'll likely have an R.I.P. Saab.
For the record I tested compression at
Light Motor vehicle Gauge Measuring instrument Gas
my other car Alfa Spider and it measured 7 bars. So even if the tool is measuring low I am afraid there is something really wrong, maybe explains why it didn't ignite when spraying starter spray. Light Motor vehicle Gauge Measuring instrument Gas
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