[JustTheTip]

Hi guys,

I've got the following problem recently: My 1990 900i 16V wont start.
When I turn on the ignition, I can hear the fuel pump run continiously, but when I crank over the engine to start it, the pump stops and the car wont start.

I inspected the pump and fuel lines, they are OK.
Should I be looking at a relais problem?

Any help welcome, as I'm on a deadline to get the car moving again.

Thanks in advance!

 

[Danilas]

Certainly the fuel pump relay should be checked. If it ok and you steel can't hear the fuel pump it definitely going to die. It needs in replacement whole pump (PN 4023057 / 5328653) or it motor - it's cheaper.

 

[Jim Mesthene]

I wouldn't rely on hearing the fuel pump.
A Fuel Pressure gauge, Voltmeter, or Test Light can all tell you more about your fuel pump than your ear.

 

[VonEss]

If you hear your fuel pump running with the ignition on, and the engine NOT running, you've got another problem all together. The fuel pump should only activate when your cranking over the engine and the ecu detects a spark signal. That same signal is then present while the engine is running and keeps the pump on. What you may be hearing is your abs pump, or iac valve. You can attach a fuel pressure gauge at the fuel rail and then jumper wire your fuel pump at the fuse block to see if the fuel pump is working correctly with the ignition on. The procedure is in the Bentley.

 

[ElGamalSaab]

Hi JustTheTip,

There are many threads which may assist you in testing and diagnosing issues with the fuel pumps. I will post links to threads that I was a part of when I first had issues with my Saab 900i 1991 N/A. Keep in mind that the cause of my issues was the ecu itself, and by replacing the ecu I managed to fix everything. However, do not disregard the posts, even if your ecu is fine, I still did all the necessary tests of fuel pumps, relays, pressures, vaccums, AIC, resistances across sensors etc and I suggest you also do the same. It takes time.

Running all the tests will help you understand more about the car, and ensure that everything is within its working range.

One place to start as mentioned is testing voltages across the fuel pump when trying to start the car, if no voltages or strange readings occur, you should then begin jumping fuses and forcefully activating components.

http://www.saabcentral.com/forums/showthread.php?p=4538825#post4538825

http://www.saabcentral.com/forums/showthread.php?p=4556057#post4556057

http://www.saabcentral.com/forums/showthread.php?p=4620705#post4620705