85 900S Very Poor Acceleration (bucking)

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W4murdza - 15 Aug 2003 17:14 GMT

85 900S 5 speed 190K

First noticed a hesitation (bucking) during a drive yesterday. The bucking
would increase going up inclines and get much worse accelerating from a stop
More like bucking then than a hesitation had to clutch to stop the bucking and
coast a bit and very slowly accelerate. OK starting, at idle and at 55mph on a
flat road or a slight decline.

Changed the fuel filter, plugs cap & rotor a few months ago. Wires Ok.
Fueled the car the day before and drove several miles. No problems noted.

My first thoughts are the fuel pump is begining to fail, low fuel pressure or a
failing ignition module causing a very weak spark. Any advice would be greatly
appreciated in troubleshooting.

Jim

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saabrepair - 16 Aug 2003 02:35 GMT

> 85 900S 5 speed 190K
>
[quoted text clipped - 12 lines]
>
> Jim

I'd bet on the fuel pump myself, but check all your vacuum lines first.

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Bill Bradley - 16 Aug 2003 02:48 GMT

>>85 900S 5 speed 190K
>>
[quoted text clipped - 29 lines]
>
> I'd bet on the fuel pump myself, but check all your vacuum lines first.

    Check your gas cap. When it's bucking, pull over and try openning the
cap. If you hear a sucking sound, you need to replace the cap since
you're pulling a vacuum on the tank (the charcoal canister is connected
to the low pressure side of the throttle as well as the tank that's why
high vacuum conditions like coming off of idle and going up hills makes
it worse). I've run into it with Volvos, VWs and BMWs, wouldn't
surprise me to see it on a Saab.

    My $0.02
    Bill

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Paul N - 03 Jun 2005 14:47 GMT

My 9-3 had a bucking problem and it was a part that needed replacement that
controlled the turbo. Was realtively cheap to fix and completely solved
the problem.

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