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Discussion Starter · #1 ·
Changing the fuel filter today on my newly acquired '85 900S, I noticed the inlet and outlet gas was pretty dirty (looked like bath water). I'm glad I got the filter, but I'd like to clean the tank out before putting it on. I did a search but I guess my terms were a little vague. What's the best way?

turn the ignition on and all the gas pump out through the filter inlet?
siphon it out at the cap?
pour something (alcohol, fuel treatment, etc.) in the tank first?
Do nothing and just fill it up with clean gas?

There's a little less than a 1/4 tank left according to the gauge. Thanks!
 

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There's a little less than a 1/4 tank left according to the gauge. Thanks!
So anything up to 20 litres left. A jerry-can full. Quite a bit. What are you going to do with it?

If there's mucky fuel coming OUT of the filter, that's purely because the filter's broken down internally, probably because it's been neglected for waaaay too long.

I'd just lob a new filter on, fill up with fresh, and - if you're really worried about the amounts of carp in the tank - change the filter again in 6mo or a year or something.

If rubbish really was getting through the filter, you'd notice it running badly, since the injectors would block in short order.
 

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I would be more concerned about crap in the little filter/screens inside the injectors themselves. IMHO, if the injectors are ok, everything is fine.

You may also want to change the sock on the pump.
 

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Discussion Starter · #4 ·
Yeah, it seems to be running fine. I was only changing the filter as a precaution (who knows when it was done last). It's definitely possible that the gas I saw was mucked up by the filter since the only gas I saw came from the inlet and outlet sides of the filter after I removed it. I'll check the gas in the inlet line itself and if it's not too bad, just replaced the filter and fill the tank with clean gas. Thanks for the feedback.
 

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Discussion Starter · #6 ·
Oh man, did someone have algae in their tank? Then again, I saw a TV special that said algae was the next big power source. :roll:
 

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Discussion Starter · #8 ·
UPDATE:

Unfortunately, I'm not registered yet (no plates) so I couldn't drive it for a full fill-up, but I put a couple gallons of fresh gas in along with some Techron, and then bolted in the new fuel filter. It's idling much smoother and revs up without hesitation. A full "field" test with topped off fresh gas may be a few weeks off, but I'm pretty happy with the outcome and am glad I didn't drain the gas. Thanks again!
 

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You thought the diesel guy had troubles- the jet engine guys have to add a bio-cide to their fuel (one trade name product is Prist). If you want to check the fuel in the tank for water, get a clean real chamois cloth, a good sized funnel and a catch container. pour the fuel through the chamois and any water in the fuel will be trapped. water will puddle in the bottom after the fuel drains through. I would shake the car to slosh the tank before trying this so the maximum amount of water will be mixed with the fuel. If you trap more than a 1/2 oz of water per pint strained, I would pump the gas into a container and offer it to the fire dept as a burn trainer. Or if you are really desperate like me, strain the whole amount through the chamois and feed it back to the tank.
 

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If you have dirty gas, chances are that you have a crack in your tank or another way for dirt to get in. The easiest way to check this is to feed compressed air CAREFULLY into the filling hose (use a rag to prevent the air from escaping), and listen underneath the car for the sound of air leaking out.

Draining the tank is easy. The best way is to take out the floor of the luggage compartment (2 screws), undo the hose clamp on the smaller of the two hoses on the right hand side, and to use a small hose as a siphon. Tilting the car over with a jack from the left-hand side will help.

Changing tanks (if you have a crack or so) shouldn't take much more than 1-2 hours depending on how rusty things are.

:-J
Jørgen
 

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... I noticed the inlet and outlet gas was pretty dirty (looked like bath water).
My bath water is usually pretty clear......

If you have no other problems, "Let Sleeping Dogs Lie".
 

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Discussion Starter · #13 ·
Alright, it was more like bath water (if I took baths) after working on the Saab all day (with an engine clean and oil change). Thanks for the tip on the compressed air. If the gas still looks dirty after a couple tanks of fresh gas, I'll try that out.
 

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Been there, done that. Norway is a WET country, and we didn't only get dirt into the tank. The buildup of water was substantial. I drained it twice, and at first I thought we'd bought it along with the petrol, but it kept coming back. The amazing thing was that the car kept running. When it finally refused to start, it was only because the Fuel Pressure Regulator had rusted to pieces. We replaced it, cleaned out the tank, and kept driving. Best luck!
 
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