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Old 4 Weeks Ago
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Default Potential failure of (or failing) fuel pump assy in 2.1 sedan

Took my newly acquired 1992 2.1 sedan for a drive to get some spare parts from one of the 'Saab servicing alumni' of Australia (Stephen Emanuel of Saab Salvage).


Car was fine on the trip down. Made one stop on the way for lunch. After a couple of hours engaging in Saab banter and collecting parts I'd requested I headed home. On the way I stopped for fuel.


Went to start the car after fuelling and it coughed/spluttered and basically would fire, but ran almost at stall revs then died every time. Got car pushed clear with help to a safe spot, tried a few things. With some technical advice the theory was a failed/failing fuel pump. Of course I didn't need a replacement fuel pump a few hours beforehand, and wouldn't have had the tools on hand to replace it on-site in the servo carpark if I did have one.



Got the car towed home (ouch cost-wise), now it's back home safe but with suspected bad fuel pump or a related issue.


I know how to manually jumper the pump to run from the fuse/relay panel.


At the servo I tried bashing the bottom of the tank, and also the top of the tank (next to where the pump assembly fits in), but it didn't overcome the problem.



Being a 1992, it's the later style of pump assembly. What are the common failures for these pumps? I'm aware that from about the mid-1980's up Saab changed the pump design from a single roller-cell Bosch unit suspended in the tank to something more fancy with a pre-pump, and plastic check-valves at the top where the fuel lines attach. No chance of getting a new pump assembly (there was one on Ebay just a few months ago but I didn't have the car then!).


Craig.
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1992 has the single Walbro pump, common with 9000, NG900, 9-3, and 9-5. Pump assemblies are easily and widely available. I have a 2005 9-5 pump in my c900. Or, you can just replace the actual electrical bit with an "insert." Fitting an insert costs far, far less but entails mucking with nylon fuel hose which isn't all that much fun.

Pumps mostly work or they don't work. Give it 12v, see what happens.
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For a backyard hack approach, if you hot-wire the pump and pulse it on & off, in a quiet environment, you should be able to hear the 'ball' bounce in the seat of the pressure regulator valve (suggesting the fuel pressure is exceeding the breakdown point of the FPR)....that and hear the fuel flowing in the lines.
Using a screwdriver or similar item as a stethoscope helps.

Sure, not absolute but can help steer the diagnosis.

The last 5dr was just short of 300,000 kms and the pump was still running strong.....
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Fortunately I still have my fuel pump manual switch box that I made many years ago (about 15!) to diagnose fuel issues on 8v 900's. Works just the same on 16v's but the connection points are a bit different. I think the Bentley manuals have it covered.


Will see what I can figure out with the switchbox and some simple checks. I'll make sure what the pump does and if it actually seems to run I'll crack the fuel rail connection and check the flow.


Car's only done 179k km's but it's spent a lot of time since 1992 parked up not running. Stuff does degrade over time and non-use can sometimes be more detrimental than regular use.
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Have had some time today while tinkering on some things ('wet' carpet, etc.). I've manually switch-boxed the fuel pump between fuses 27 and 30, and the pump runs. I cracked the banjo at the front of the fuel rail, and fuel sprays out. So no fuel filter blockage.

Just for ****s and giggles I pulled all the connectors off the AIC, AMM, TPS, etc. and put them back. Cranked, and the motor started, idling spot-on. Ran is for about 5 mins.

So I know the wiring between fuse 30 and the pump and ground is all good. And now the motor has cranked and started, I know the wiring through the system relay and fuel pump relay to the other side of fuse 30 is all good. I didn't get my hand on the two relays as I don't have time to pull the centre-console, knee bolster and carpet to get my hand up to the relays.

None of this proves the fuel pump is 100 pct though. But it does rule out IMHO the crank sensor as if it wasn't working the ECU wouldn't get the signal from the EZK box to tell the ECU it's ok to turn on the fuel pump relay or produce the signal to the ignition amplifier module to fire the spark plugs.

I also took off the distributor cap to check it and the rotor. They're both new fitted by me a week ago. What I did find is the distributor o-ring seal(s) need replacing as oil is getting into the distributor body (and therefore the cap).

What I might do in the interim is keep the fuel pump switchbox in the car in case the pump seems to play up again. My wiring links aren't really up to on-road use but that can be fixed:





pic page


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I disagree , You certainly haven't eliminated the CPS as a potential problem .

THEY CAN BE intermittent failures , usually heat related .

When you couldn't start the car , I believe you had been on a significant trip , not running it for 5 minutes.

Next time it doesnt start , DONT assume it fuel pump ... Check you have spark .

Order of checking for a non start is Spark , then FUEL
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Pardon my ignorance, but what fuel system are you running Bosch or Lucas?
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In OZ Paul , I believe we still had Bosch in 92 ,
I haven't seen a lucas system on a 2.1 here ,
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Ok. Never had a 2.1. I find Lucas systems so much easier to work on although some guys hate 'em.
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It's a Bosch system. LH 2.4.2 + EZK.



It's possible that unplugging and re-plugging the electrical bits on the motor might have been the cure but in any case I still did basic fuel pump tests to be sure.


Agreed that the CPS could still be an issue though the simple tests didn't appear so. It'll be the rheostat type not the microswitch type.



Correct I'd just driven about 200 km (with two stops already) before the problem occured. And the motor was hot since I'd stopped at a servo to fuel up.
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c900 CPS is a Hall-Effect sensor ("shutter wheel"). Works exactly the same as the distributor-mounted sensor, just in a different, less convenient, and maybe less reliable place.
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When I had a heat-sensitive failure that I suspected was a Hall Effect sensor, I tried cooling the sensor with a spray of Brakleen.
I thought it was a great idea, but it only worked about 50% of the time.
Still, 50% is better than nothing and you can just squirt some water on the crankshaft-mounted sensor. I like diagnostic tests that cost nothing.
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Quote:
Originally Posted by jvanabra View Post
c900 CPS is a Hall-Effect sensor ("shutter wheel"). Works exactly the same as the distributor-mounted sensor, just in a different, less convenient, and maybe less reliable place.
Apologies I mean TPS (throttle position sensor) that tells the ECU whether to use the idle control loop or not.

But yes the CPS can go bad. Replaced the one on my black 2.1 hatchback. Was a pita because of the limited clearances to get at the crank pulley, etc. area. Ive still got the cut-down socket I used for that job somewhere. ;-) BTW Bill (from Saab bits in the UK) sells a kit to replace the hall sensor.

I just finished a big de-grease to get rid of as much of the long term steering fluid leaking/weeping and will go from there with more testing of the motor controls once that's all dried out.

The plan is to run the motor and let it get to full temp just idling then shut it off, leave for about 10 minutes (to simulate what I did when I was fuelling up at the servo before it wouldn't re-start) and try to replicate the fault situation. I'll do it a couple of times, and might fiddle with (wiggle around without actually unplugging) the connectors on the TPS, AMM, etc. while the motor is idling.
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Last edited by c900; 3 Weeks Ago at 09:53 PM.
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Default Investigating the bad hot start issue some more

Ran the engine yesterday just idling to try and replicate the unforunate event a couple of weeks back.


After about 20 minutes I got a 'check engine' light pop up and the idle started to gradually 'wander' back and forth between about 100 to 150 rpm like a hysterisis curve.


Once the fans ran a few times to tell me the motor had go to operating temp I had a go at getting the fault codes out and besides the 'standard' 12231 (no rpm) I also got 12223 and 12112 both of which are related to incorrect air/fuel mix at idle.


So going to try the same thing again this time I'll connect a meter to the O2 sensor and watch it's signal swing to see if it's in the correct range, and check all the intake side hoses for breaks/leaks.


I think I have a spare -019 AMM somewhere in case I need to try swapping that part.
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That sounds like typical MAF (AMM, whatever) failure. If you have one to swap, I'd give it a go.
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Hi there, I’m new to the saabcentral forum world, so forgive me if this question has been asked before. I’ve got a 2006 Saab 93 1.8i linear sport. While attempting to test the o2 lambda sensor for power I accidentally shorted two contacts together. I didn't think much of it at the time however when I went to start my car it wouldn’t fire up. It’s cranking perfectly fine and is generating spark. I suspect that I have blown a fuse for the fuel pump as no priming noise is evident in the “on” position. After consulting the owners manual it shows that the fuse panel in front of battery contains the fuse for the fuel pump and ; preheated oxygen sensor (No.2 Amp.20) however my only issue is my car does not have a fuse panel in front of the battery so I have no idea where that fuse is in my car. Some help or advice would be greatly appreciated as I have spent hours diagnosing and searching for the problem and nothing so far has worked. Thanks
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Quote:
Originally Posted by SaabEire View Post
Iíve got a 2006 Saab 93 1.8i linear sport.
Ask here instead: https://www.saabcentral.com/forums/f...splay.php?f=30
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