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1988 Saab 900S rough running

On the 2/27/10 show that aired on Minnesota Public Radio, a caller said his Saab 900S ran rough when the gas tank got to about 1/2. The problem is common to high mileage Saab 900s.

There are TWO (2) fuel pumps in the 900 gas tank. The main Bosch pump is the high pressure pump that provides fuel to the engine. It resides in a plastic bucket at the top of the tank. There is a small, low pressure pump attached to the bottom of the bucket that keeps the bucket full so the main pump always has fuel to keep it cool. That smaller pump is more prone to failure. It is not very expensive, maybe $30-$40. It is easy to access and replace the fuel pumps. I have done the complete job in about an hour.

The listener also commented that it seemed difficult to fill the car at the gas pump. Yes, I have had this problem as well. Just pull the nozzle out a little to allow the tank to breathe and there is no problem filling the tank.

(Note: I erroneously posted this same message under Repair and Maintenance. Moderators are welcome to delete that one.)

Here is a diagram of the 900 fuel pump setup.

From day one my 1992 SAAB 900 suffered from hiccups during refueling. But it seems to depend on where I refuel. I agree with “WinkTimber”; stop pumping for a few seconds, let your fuel tank settle down, then continue pumping.

Saab 1988 is one of the best car for me. I may not know full details but the diagram show already how saab parts has the quality. And thanks for this, the set up will make a lot easier now.

I could not believe when I read about rough running 88 saab 900s at 1/2 tank! I have been battling this problem for some time. Fill the tank no problem right? Have been through and through the fuel pump and still have the problem. Happened to me with full tank, finally shut completely down. If your fuel pump is working with sufficient pressure i.e. checked with a gauge, check the MASS AIR FLOW SENSOR. Found online for about $160 after $ 60 core charge. It took my third mechanic to figure it out. By the way can anybody help me with something that is driving me crazy! Is there a difference between a 900 and 900s? Every reference I check starts out referring to the 900 s and the verbage changes to just 900 without the s. HELP!