Messages

31

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 24 April 2024, 09:07:36 AM »

The level sensor feeds were the first thing I checked with the Tech2.  They arrive at the ECU separately, but Tech2 only sees the combined value. Actually it only reports the lowest of the two, which is why the gauge falls to zero when one goes open circuit.

It may be warm enough today to work on the electrics without dropping anything.  I’ll try.

32

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 24 April 2024, 12:14:17 AM »

The V6 fuel system does not have a return pipe through a pressure relief valve.  The pump is electronically controlled and varies the fuel pressure under the control of the ECU.

I have cans of Forte engine and injector cleaner coming tomorrow. 

The P0089 fault in WIS does mention it being triggered by no fuel.  It also mentions a blockage in the fuel line.  I'm also thinking about a loose electrical connection.  The level sensor may have a a fault but separate to that, if one of the level sensor signals to the ECU is broken for a moment or two, the ECU may think the tank is empty and trigger P0089, it won't show on the gauge because that has a damped response.  Perhaps I can read the instant fuel level with Tech2...

She went out to a singing engagement tonight.  No engine light on the way there, but it came on as she started to drive home. 

33

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 23 April 2024, 09:40:00 PM »

No, I didn't.   I'll double check the circuitry when it's warm enough for my fingers to grip the multimeter probes...

I have been thinking that the P0089 fuel pressure fault and the level sensor fault may be linked,  but I think that will depend on the fault being in the sensor attached to the pump, rather than the separate sensor in the other half of the tank.

I was also pondering if there's a pressure drop or spike when the pump starts up.  From my hydraulics background, I wondered that if there's a small blockage in the feed.  If it stops the flow briefly the pressure will be lower than expected at the sensor and could trigger a fault.  If the blockage releases suddenly, the pressure would surge and also trigger a fault.  That sort of blockage is typical of a sticking non-return valve.   Further reading required...

34

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 23 April 2024, 05:15:26 PM »

Oh! ****

In a gap in the rain I went out, cleared the code, set the Car Scanner to show the fuel pressure.  Went out and retraced the route she did last night, then came home via the motorway and the supermarket.  The light stayed off.  So no data to compare.

35

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 22 April 2024, 10:11:08 PM »

Oh well!  She's home and the engine light is back on...

If it's coming on more regularly, I'll clear it, run with the pressure recorder and see if I can pick up the instant it triggers.

36

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 22 April 2024, 07:47:19 PM »

That's the consensus on the internet, but I've run a long record of pump pressure and it hasn't dropped at all.  There's no suggestion of hesitation at full throttle, so when it first happened, I changed the sensor and it seemed to solve the problem.  Six months later it was back and I heard a theory that the filter allowed very fine particles through which, over time, sat in the far end of the fuel rail.  It was suggested that I filled the fuel rail with fuel treatment, which i did and the light went off again for almost a year  Now it's back.

I filled the fuel rail again with the intention of leaving it standing overnight, but the failed battery meant that the treatment stayed in for 36 hours.  It's started and I've run it a few miles and the light is still off.  I felt the engine was running a bit smoother, but it was maybe my imagination.  The SWMBO took the car out and when she came home, said "What did you do to my car? It's running a lot smoother than is was".  Maybe the fuel treatment has cleared an injector, or maybe the new battery is helping.  She's out on a much longer drive this evening.  We shall see if the light has stayed off.

I'm hoping it stays dry enough to check the level sensors tomorrow, if the rain stays away, but it isn't looking promising.

37

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 22 April 2024, 01:35:39 PM »

Nothing today.  It's cold and wet.  We had a frost overnight.

38

Off-topic chat, Help, Advice, General motoring issues / Re: Peeling lacquer

« on: 22 April 2024, 01:31:30 PM »

The problem you will have is that the exposed paint will be dirty.  Unless you get it really clean, the lacquer won't stick.  And, it's clear that the exposed paint is not suitable for getting lacquer to stick, as it hasn't stuck before.  So you will probably need to sand down to get a key, which will expose the metallic particles and alter the finish.

Maybe a good clean and de-grease and a coat of lacquer is all you can achieve, in situ.  But expect to have to do it again in a year.

39

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 21 April 2024, 11:15:00 PM »

OK, so that points to a break in the sensor resistance at high level.  The resistance for a break being infinity, it would give a reading of empty.

40

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 21 April 2024, 07:27:16 PM »

It's sunny now, but too late to start anything.  I may have a bit of time tomorrow, but she needs the car at some point.

One point I realised was that the CarScanner report said that the level sensor failure was "high output", which implies that there is less resistance than expected.  So the sensor must reduce the current as the level drops.  But it also implies that the sensor has a short circuit, not a break as I had imagined.

41

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 21 April 2024, 01:57:29 PM »

I think I'll try the ECU once it's refuelled.  I got the new battery fitted.  Now it's raining again...

42

Off-topic chat, Help, Advice, General motoring issues / Re: Peeling lacquer

« on: 21 April 2024, 12:03:16 PM »

Take the bumper off.  Rub it down and start again with a primer.  If you just try and replace the lacquer, it will still look odd.  You really need a key for the lacquer, and if you rub down the black, it will look like it.  A fresh coat of black with the lacquer a few minutes later without rubbing down.

43

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 21 April 2024, 09:22:07 AM »

There is supposed to be an accessible connector in front of the tank.  That’s my only hope for a DIY diagnosis.  Once (if) I have pinned down which sensor is damaged, I’ll probably get the garage to fix it.  It’s due a service/MOT by the end of June and they will be around the back of the car as the rear Haldex is due a service and clean out.

New battery this morning.  Halfords were closed by the time I got there, due to a road closure, diversion and subsequent traffic jam.

44

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 20 April 2024, 08:06:55 PM »

I have found the connectors on the front wing for the fuel level sensor wiring.  But, sadly, I feel it's too risky to have go at splitting them. 

They might be more accessible if I take off the bumper and remove the LH headlamp.  The connectors are low down, fixed to the inside of the inner wing, under a lot of loom, and bits of the loom are clamped and tied down.  It could be done, but I took the battery tray out for access, and it showed that a lot of the plastics are now very brittle.  The battery tray was easy as the battery is dead and was out of the car anyway.

I think it's the first time I've needed a T40 Torx screwdriver!

Picture of the 24 pin connector, looking straight down. usually hidden by the battery tray...

45

Saab 9-3 Sport Saloon / Convertible / Combi (Wagon/Estate) / Turbo X / AWD (2003 on) / Re: 93 V6 fuel pressure release.

« on: 19 April 2024, 05:49:36 PM »

I put the battery tester on the battery and it said "Bad - 23%", but I'll check it again after a run as the tester requires a fully charged battery, and I'm not sure that it is.  If it is bad, it's not quite 4 years old and it has a five year guarantee,

I've dismantled the fuel pressure sensor again.  The engine light stayed off this morning, but came on on the way back home at lunchtime.  I had no problem with the fuel pressure release, not much fuel came out of the valve and none when I pulled the sensor out. More oddness.  I've left a slug of fuel system cleaner in overnight as it started to rain again...

I cannot find the connectors at the front for the fuel level sensor.  There's nothing that looks like the WIS.  I'll have to go in under the back when i can guarantee a warm few days.