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Discussion Starter · #1 ·
My temp gauge sender is on the fritz, sometimes it'll jump down to almost zero, but I can temporarily make it work by jiggling the wires on the sender at the end of the motor.

Thesaabsite sells a replacement for not too much $, but I've got a couple questions.

They mention that one unit fits up to a certain engine number. I've got a '94, so I'm probably safe, but I just looked at my engine and didn't see an obvious number. Any guess about where to find it? I did see a number stamped into the ps bracket, but I assume this isn't the engine number.

How the heck do I disconnect the overly clever red connector thing that sits on a bracket under the "silencer". I managed to get it out of the bracket, but I can't figure how to unlatch it. Since I don't even have the sender yet, I decided to seek advice from the wiser minds here before I broke it.

In other news, I successfully replaced my fuel filter today, Wohoo!
 

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JMarkert said:
In other news, I successfully replaced my fuel filter today, Wohoo!
Did you do it with pressure in the system or pull the fuse and run it dry?

As for engine numbers, I believe their are some numbers stamped on the distributor side of the head. I think at some point Saab decided that the diameter of the temp sensor was too small or something like that, I think I read it in a TSB.

As for the wiring plugs, what you do is this: you pry that red portion away from the body of the plug. You'll hear it click out, but you need to keep going with it, until its pulled out about half to three quarters of an inch, then the connection should part nicely.
 

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Discussion Starter · #3 ·
Did you do it with pressure in the system or pull the fuse and run it dry?
Thanks Nate!

Pulled the fuse and let it run dry. There was still some pressure in it, and of course the whole cannister is full of gas (how the heck do I get rid of a half a can of gas legally in the city? a problem to solve tomorrow I guess).

I'll take another look on the distributor side in the morning and see if I can find numbers. And I'll just pry on the red thing when the new sensor comes in.

Oh, and it looks like I'm finally moving Nate-land in the fall! Rhode Island here I come.
 

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I've read the whole thing about not running the system dry with the engine running because it ruins something in the pump, but I did it over 20k miles ago and nothing has changed. As for the connector, you will see their is a little recess to fit a screwdriver head into.

No kidding, what part of RI are you moving to, or is that still up for debate?
 

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Discussion Starter · #5 ·
yup, i saw the little slot and poked at it with a screwdriver, but was afraid to really pry until i got more advice.

I don't know about pump failures, but i can see how the FPR could go, it would be really really easy to get some grit into the system while doing this. Perhaps that's the source of the FPR trouble.

I believe the folks who've had fuel pump trouble after the replacement, but it's really hard to understand why pulling the pump fuse would do any harm. The pump isn't running dry, it's submersed in the tank, and the lines are still full of gas, it's just the pressure has dropped some (but not zero!). And besides, it's not actually running when the pressure drops, and anyway, the system is partly empty with the new filter no matter what you do.

I'm probably moving somewhere near Narragansett, but not sure exactly where yet. An easy commute from a place I can afford, hopefully.
 

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JMarkert said:
... i can see how the FPR could go, it would be really really easy to get some grit into the system while doing this. Perhaps that's the source of the FPR trouble.
I have seen some speculation on the SN board that FPR failures can be caused by particles coming off the rubber coated washers used on the fuel filter.

Another explanation I heard was something like this: The role of the FPR is to maintain a stable fuel pressure relative to the intake manifold - lower when cruising, higher when on boost. When the engine is started with the pump disabled to relieve pressure in the fuel lines, the FPR diaphram is stressed outside of its normal operating range as it tries to adjust pressure with no fuel supplied by the pump. A new FPR will do just fine. An FPR with an old diaphram may not survive the strain. Running out of gas can cause a similar problem - the FPR can fail due to a combination of age and stress with no fuel pressure.

No evidence to support either theory though.
 

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Discussion Starter · #7 · (Edited)
Both theories seem credible though. There were certainly a lot of little rubber washer bits to carefully clean out of the screw thingy, it would be easy to miss a couple. And the FPR range story makes a ton of sense. Perhaps we can just forget about all these messy fuel pump stories and declair this mystery settled? :)

But wait, the FPR is just mechanical, isn't it. Wouldn't the diaphragm go out of its normal range when the pressure drops for whatever reason? It shouldn't care if the pressure drops b/c the fuse is removed, or if it drops a lot a couple minutes later b/c the line is open. So, we have a proximate cause for FPR failures after a filter change, but no evidence either way for whether pulling the fuse is good or not.
 

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I did not mean to suggest that pulling the fuse was worse. I heard the same explanation for fuel system problems after running out of gas... again, no evidence, and who takes an FPR apart after it fails... Some suggest substituting copper washers for the rubber coated ones, but my new fuel filter seems just as happy with the stock rubberized ones... <shrug>

The coolant temp sensor did change, not sure when. Aside from the year and ID number, you can look to see if it has wires attached or not. eEuroparts has pics.
 

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TSB #260-1869:

Revised diameter for the engine coolant temperature sensor in the cylinder head
Cars affected

Saab 900 and 9000 4-cyl. M94-M97, up to and including engine number V002172.

Background

The cylinder head has recently started to be delivered as a spare part with a larger diameter opening for the engine coolant temperature sensor.

The new cylinder heads are Factory-fitted on M97 from engine number V002173.

Attached is the part code numbers:
 

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Discussion Starter · #10 ·
Thanks folks - my sensor does have wires attached to it, and I've got a 94, so I can go with the old style (and cheaper :) ) sensor.
 
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