1991 900 problem

[albany175]

While driving through the wilds of Western Pennsylvania my wife's 1991 Saab convert quit. No notice, no warnings, no sputtering it just cut out.

Was towed to a local garage who had never looked under a Saab's hood before (couldnt get it open) and they concluded that the Saab's security system may have cut in and killed the power to the fuel pump. He jury rigged a circuit and put a switch on it.

My questions are these:

Do these things just quit?

What is the box under the back seat actually called and how do I replace the damn thing?

[gotaquestion]

Think that there are a couple of reasons that the fuel pump would be disconnected by the Saab electronics. One is if it thinks that you are in a collision, so that gasoline will not still be pumping. Other made sense when I read it, but can't think of it now. Check Bentley!

There is an ABS box under the rear seat of C900s with ABS. And an auxiliary fuse box. Did you mean another box?

What circuit did he connect?

[eggsngrits]

We'll probably need more information to identify the true "deal" here, but the standard alarm system on this model is an audible/visible alarm only. There are no "shut off" features on the standard alarm system.

Naturally, there could be an after market system on the car.

As for "the box" under the seat, there could be several possible candidates. The standard alarm control center is a 3" x 3" (approx.) plastic square that is identified as such. There are other things under there.

Did the bypass installed by the mechanic get the car running again? If so, you could be dealing with a relay failure. The fuel pump relay is located under the trim in the right front foot well.

[gotaquestion]

I do not think that he means an alarm. It is a safety feature of Saab to shut off the fuel in the case of emergencies. Sounds like it did not work right this time, if that is what it was.

[eggsngrits]

Originally Posted by gotaquestion

I do not think that he means an alarm. It is a safety feature of Saab to shut off the fuel in the case of emergencies. Sounds like it did not work right this time, if that is what it was.

I know of no such specific system on a C900. There are indirect ways that the fuel pump will shut off if there are system faults, but those are not specifically for safety.

[900t]

Originally Posted by eggsngrits

I know of no such specific system on a C900. There are indirect ways that the fuel pump will shut off if there are system faults, but those are not specifically for safety.

I think the one that is "safety" is the one that shuts off the pump when the crank-sensor / hall effect sensor reads zero RPM the pump doesn't run. There isn't any weird "inertia" switch like on Fords.

I'd look at the pump relay first... if the car runs with a jury-rigged power to the pump, the problem is probably trivial or an aftermarket alarm also