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Discussion Starter · #1 ·
1989 9000 2.0 non-turbo 150,000 miles

Starts after a fair bit of turning, but will die after 10 seconds. Attempts to rev the engine cause spluttering and coughing.

Hard-wiring the pump I can get fuel flowing freely through the injector rail to the pressure regulator's input, but when I reconnect that, nothing comes out the other side of the regulator. So, my pump is not producing sufficient pressure to flow through the regulator.

This suggests that the fuel pump is weak and that it is not producing sufficient pressure to run the engine. Or will a siezed-shut regulator (causing over-pressure) display the same symptoms ?


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More diagnostics....

Was given various second-hand 'useful spares' with the car.
Tried 2 other ECUs - no difference.
Tried another airflow sensor - no difference.
Unplugging the idle control valve - no difference.
Checked the throttle position switch - all works as it should.
Sparks are strong and continue to spark while engine is misfiring.

I've looked on various BBs and forums which suggest possible causes, but........
There is no DI cassette thingy on my car, so it ain't that.
All hoses and electrical connections are clean and in good condition. No vacuum hoses are split/holed.
It isn't a blocked filter, because fuel flows freely as far as the in connection to the pressure regulator.

The car has run well enough in the 2 months I've had it - this problem came on without warning over a few miles last night while cruising at 60. It has done it twice before, but both times it started again and ran perfectly after a 10 minute rest by the side of the road. This time, it seems permanent.

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Mike
 

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Discussion Starter · #2 ·
Found an interesting comment from scaero in another post:

>>The pump will run for 1-2 seconds after the key is switched on and then turn off, only switching on when the fuel pressure drops below a certain point.

>>with the car running (idleing) this is normally every few seconds for 2-3 seconds.

My pump seems to run continously - whch seems to lend support to my 'low pressure from pump' hypothesis.

What do you think ?

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Mike
 

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I've got the same problem that I've been trying to get to the bottom of for 6 weeks. When I came home from work the car was mis-firing really bad. The next day it wouldn't start. I first suspected the pump, but it seemed ok. Secondly I suspected the earth on the fuel pump relay but this seems ok. Then I suspected the ECU but again this seems ok, so I am back to square 1. I have both a spark and fuel and the car turns over but won't fire into life. Now after reading your post maybe it is the fuel pump after all. My car is a 1988 9000 CD with roughly the same miles. This weekend I will measure flow rate of the pump again. Let me know how you get on.
 

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From my experience of fuel pumps it seems that they have a life of approx 150,000 miles(ish) this is based on my pump that died at 132,000 and the second hand replacement one that died 10,000 miles later (the donor vehicle had 140,000 on it. I then was forced by circumstance to buy a new complete unit (ouch). The new pump is much quieter than any of the others - it emits a faint high pitched hum, and I couldn't say that I ever hear it stopping and starting when idling. I fact I'm not sure it does because there is a return circuit in the pump system so that unused fuel is returned to the tank. When the engine is cranking and not starting it may well stop pumping, but if a brand new pump needs to run all the time even when idling I think a low pressure problem with your pump is unlikely. On that point when a pump can't deliver enough fuel the symptoms are clear, the engine will start and idle but will refuse to be 'worked' that is any application that requires more fuel. I know this because my first fuel pump repair attempt became unstuck when one of the internal hoses collapsed and reduced the fuel flow a trickle. This can happen with a blocked fuel filter. A dying fuel pump will often make noticable noises kind of like a growl or will change pitch as the motor experiences more and more resistance. When you pull the motors out you can see the shards of metal left in the housing by the grinding! In your case I would concentrate on the ignition system some more esp. if it actually misfires (rather than has fuel starvation) Let me know if you want to know more about fuel pump fixing/removing.
Cheers
George
 

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I had something similar happen last winter...

My 1990 9000i would start (just barely), but when I stepped on the gas to get going, the revs dropped, and the car stalled. This would continue for as long as I cared to try it... If I did get the car moving, its acceleration would be very poor, and shuddered terribly.

I left it for a few hours, and when I returned, it worked just fine! Magic? No, it turns out that having the car sitting out in the sun all afternoon melted the ice that had formed in the fuel lines.

I added some fuel antifreeze, and it worked like new! From then on, whenever the temperature gets cold (below freezing), I add a bit of isopropyl alcohol to the tank. Usually, about half a pint to a pint for every tankful of gasoline is adequate.

It might be worth trying, since IPA is pretty cheap, and you can buy it in your local drugstore. Just make sure you buy the 99% stuff, not the 70%!

let me know if it works

Rocky
 

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What you could do is remove the fuel pump fuse and measure the resistance of the circuit.probe the feed wire to pump the other probe to earth you should have a reading of about 1-5ohms high resistance could indicate wiring fault(poor earth) or tired pump.
secondly connect an amp meter in line,bridge the fuel pump relay and measure currant draw,this should be between 4-8amps.High amps may indicate blockage or weak pump.low amps may indicate no fuel,low pressure etc.
Hope this is of some help.
 

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Another possibility is that you've dragged up a load of rubbish from the bottom of the tank and that the fuel filter has somehow got blocked as a result. It wouldn't hurt to change it anyway and they're relatively cheap.
 

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Found an interesting comment from scaero in another post:

>>The pump will run for 1-2 seconds after the key is switched on and then turn off, only switching on when the fuel pressure drops below a certain point.

>>with the car running (idleing) this is normally every few seconds for 2-3 seconds.

My pump seems to run continously - whch seems to lend support to my 'low pressure from pump' hypothesis.

What do you think ?[/b]
I'm afraid I cant help with your fuel pump diagnosis but the operation of the pump is that it will start to run when the ignition is turned on, thus pressurising the system. If the engine is not started it will switch off after a few secs, but if the engine is started the the ECU will keep the relay energized to that the pump continues to run. So the pump will be operating all the time the engine is running.
 

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Discussion Starter · #9 ·
Thanks for all the suggestions guys,

Circuit resistance is 1.1 ohms, current draw is 4.46 amp.

I checked again today. Fuel definately flowing well through the fuel rail. Putting my finger over the end stops the flow. Releasing finger sprays fuel like it was under pressure. But I have no way of testing how much pressure.

Reconnecting and removing the return line after the pressure regulator, no fuel comes through the pressure regulator.

Looks like I'm replacing the pump, I'll let you know if this fixes it.

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Mike
 

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I have no idea of the pressure of a Saab fuel pump,but I would advise against putting fingers over the end of fuel pipes,an acquaintance lost his arm after doing just that on a diesel engine.
mike
 

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Discussion Starter · #13 ·
Thanks for all your help and suggestions, guys. Normal service has been resumed.

I didn't really want to become an expert on Saab fuel pumps, but here is the info, in the hope that it helps somebody else in the same situation.

There are (at least ?) 3 types of pump assembly fitted to late 80's/early 90's 9000s. The early type which mounts with a big rubber diaphram thing - I know nothing about them.

The later type has 2 variants, both mount with a black plastic ring. Early-late has a separate fuel guage sender unit, the pump has 2 wires connecting to it. Late-late (which may be the same as the next model 90's 9000) has the fuel guage sender integrated with the pump assembly, and a wiring connector to the top of the assembly with 4 wires.

The black plastic ring attachments are actually completely different. I have an early-late car, but I could only get hold of a late-late pump assembly. So I can tell you that it is a simple job to disassemble the unit and change the pump itself. The big container thing comes apart easily, the pump itself comes out inside a gauze filter housing. This pops straight into the other type of container. I did have to get jiggy with the pipe attaching to the top of the pump - damn shrunk-on plastic pipe - but it all went back together smoothly.

I now have fuel flowing through the pressure regulator at idle, and the car runs fine again.

Incidentally, the 'plumbing' is different in each type, the late-late having a T-piece above the pump. I plumbed mine up as my early-late was originally. Since the car seems fine now, I'm not going to worry about the difference - unless somebody tells me the actual pumps are different, and late-late _must_ be plumbed as a late-late......


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Mike
 
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