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Discussion Starter · #1 ·
Lets see if this post makes it to air as none of my other ones have been posted.
Many issues with the '96 900S I was given. I want to check the power to the fuel pump. How do I get the plug apart for the yellow wiring under the rear seat to test it? Push, Pull, Pry??
Hopefully this one will get published and I can start getting some assistance here as you look like a very knowlegable lot.
Thanks all

Paul
 

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http://www.saabcentral.com/forums/showthread.php?t=61165
One of a number of excellent posts on this subject.
With your multi-meter and a needle, poke/probe...carefully of course.
You can also use an inexpensive test light....
Haynes (ref)
Black/Green is FP +
black is FP -
fuse 32 is the current source
The other wires are for the fuel level sending unit.
 

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Discussion Starter · #3 ·
So, the wires inside the opening under the rear seat aren't for the fuel pump? I am not with the car now But I recall yellow wires. What my main issue was, to test them, is that I couldn't get the connection apart at the plug. there are two sets there.
I will repost my itroductory thread to give an idea of my issues and the vehicle in question.
Thanks
 

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The cover under the back seat gives access to the fuel pump wiring, yes.

As EW posted above, one connector is for the pump motor, the other one is for the float sensor.

If you want to test the pump power, you can also do it from the fuel pump fuse. With the fuse plugged in, you should measure around 12 volts to ground with starter engaged and engine cranking. (or engine running). With the fuse out, and meter set to measure amps, and connected in series (across the fuse terminals) , you can measure the fuel pump current, etc...

edited to add:

The red cap is the connector lock. It should have a small slot on the edge for the tip of a small flat blade driver to help slide it out. Once pulled out, the connector can be unplugged.
 

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Discussion Starter · #5 ·
That seems easier, thanks. Bear with me please as I am an MGB Man and have dealt with Lucas wiring for years. This beast has me totally stumped in just four days.. If the car wasn't free to me, It would be heading to Saab heaven by now I think. :)
 

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Discussion Starter · #6 ·
Hummm.. I posted an introductory thread again and was informed that it had to go through a Mod. again. What is up with that? :(


And thanks for the tip on the cap..
 

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Discussion Starter · #8 ·
That's odd, I've never had a post go through a mod. Did you list another site or something?... Ron

Nope. This is four posts now that have given me that response and never appear. The site let me post last night the all of the sudden.. wouldn't. This is more frustrating then the car...
Is the site based on IP addresses as I post from work as well as from home..
 

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Discussion Starter · #10 · (Edited)
The cover under the back seat gives access to the fuel pump wiring, yes.


If you want to test the pump power, you can also do it from the fuel pump fuse. With the fuse plugged in, you should measure around 12 volts to ground with starter engaged and engine cranking. (or engine running). With the fuse out, and meter set to measure amps, and connected in series (across the fuse terminals) , you can measure the fuel pump current, etc...

So there is both a fuel pump fuse and a fuel pump relay, which appears to be under the steering column. Does the power go through the fuse first or the relay first. And.. what kind of sound is the fuel pump supposed to make? A tick tick like my MGB's or a humming sound? Either way I hear nothing. I used a test light at the fuse and I have power on the one side of it and the fuse is good. And. looking from the top, which relay is the fuel pump relay. The manual only gives letters and I think it calls it "L"

Paul
 

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So there is both a fuel pump fuse and a fuel pump relay, which appears to be under the steering column. Does the power go through the fuse first or the relay first.
Relay, then fuse.

And.. what kind of sound is the fuel pump supposed to make? A tick tick like my MGB's or a humming sound?
Humming sound.

When you turn the key from ON to START, the engine cranks, and the CPS generates a signal as the aperture disk passes in front of the sensor tip. If the engine control module (ECM) sees a valid signal, the ECM closes the fuel pump relay, the relay applies power to the fuse and from there to the pump, and only then you can measure power at the fuse. If the engine does not start and you release the key (from START back to ON), the CPS signal stops, and the ECM turns off the relay. If the engine starts and runs under its own power, the CPS continues to output a signal, and the fuel pump continues to run.

You can hear it best with ignition (and everything else) off, if you power the pump directly from the positive battery terminal, either to the fuel pump fuse socket using a long jumper cable or wire, or at the access panel. That's what the access panel is for.



And. looking from the top, which relay is the fuel pump relay. The manual only gives letters and I think it calls it "L"
See link: Relay Tray
 
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