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wae PowerDork
2/20/23 3:32 p.m.

Over the weekend, my daughter and I went down the road a little bit and met up with Powar so that we could drag home the 1990 Saab 900 Turbo Convertible that he had for sale here on the forum.  He said that he originally got it as a parts car, but thought it might be a little bit too nice to tear up, so he offered it up for sale.  At the same time, I had been thinking about getting another "regular" car since my eldest daughter turned 16 back in November and my middlest daughter is going to be 16 in another year, so having a car that I don't mind the kids driving around wouldn't be a bad idea.  I also wanted to give her the experience of dragging home a car that doesn't run and getting it brought back to life.  She also thinks it would be a cool idea to put together something for the $2000 Challenge and go to experience that.  This certainly won't be any sort of radical build or anything that would land in the top two thirds of the field, but it'll be a good time and a good learning experience.  Most importantly, however, this is not "her" car.  I paid for it, I'm buying the parts, and I may let her drive it if she's nice to me.

Step one was to go down and pick it up.  With the new winch installed on the trailer, it was a cinch to get it loaded up:

Der Scheißwagen towed it like an absolute dream.  I set the cruise control at 70 and it went up I71 with all those hills with no drama and no downshifting.  I think it got about 18mpg as well for the round trip.  Home safe:

Don't mind the missing headlight.  The adjusters are broken and I've got new ones on the way.  Powar wisely put the headlight in the trunk for me so I didn't have to worry about it falling out on the way home.

Today's task was to get it off the trailer and in to the shop.  I can't really keep it outside because the top is torn in a couple places and I didn't really trust tarping it.  So we went over to the shop and cleaned things up, moved things around, and were able to get this and the Miata to sit side by side:




It hasn't been on the road for quite a while so it's going to need to be brought back to life.  The gas smells really old so that'll have to be drained out and replaced with fresh.  There's also going to be some discovery, of course, but so far here's what we know about:

  1. Fuel pump
    1. Known bad, new one just arrived
  2. Drain fuel
  3. New battery
  4. Oil and oil filter change
  5. Brake fluid change
  6. Coolant change
  7. Ignition switch
    1. The switch itself appears to be faulty.  Powar said that by bypassing the switch he could get it to run on starting fluid
    2. Used ones are $100-$150 on ebay.  I'm going to see if I can take this one apart and fix it.
  8. Tires
    1. They literally have chunks rotting out of them!
  9. Front left brake is pretty seized up making it almost impossible to push around
    1. While the winch didn't have any problem with it and rolled down the trailer, no problem, both of us pushing couldn't get it to roll on the smooth and flat shop floor.  I had to jack that one wheel up and roll it on the jack to get it in far enough to be able to close the door
    2. Plan is to do new pads and rotors all the way around, rebuild that caliper, and get new soft lines
  10. Convertible top
  11. Headliner
    1. Because of the water coming in the top, the headliner has copious amounts of mold and mildew.
    2. I'm going to try the carpet machine to get it cleaned up
  12. Belts and hoses

Once it's a runner, I'll be able to see what else it's going to need to be a driver and from there I'm going to see what it needs to be a little more fun.  It looks like the boost controller can be modified to gain some power and I've read that they respond fairly well to cutting a coil out of the springs.  I'll probably go for some new shocks at the same time.  There are a few spots where rust is starting to form, but rather than try to get in and cut it out I'm going to just hit it with a wire brush and some POR or other encapsulator for now.

Powar UltraDork
2/20/23 4:23 p.m.

I'm glad this one stayed in the family. I think it has potential to be a good cruiser. 

clshore Reader
2/20/23 5:06 p.m.

As a young man, I worked for Saab-Scania (the Datasaab Division) in mid 1970's , installing and maintaining Banking Terminal Systems, and we had Saab 99's as company vehicles.
Since then I've always had a soft spot for them.

wae PowerDork
2/20/23 5:07 p.m.

In reply to Powar :

My daughter is already talking about the places she's going to go with the top down and which friends are going to get to go with her.  I like to just smile and ask her why she thinks I'm going to let her drive my car!

759NRNG PowerDork
2/20/23 7:51 p.m.

y'all with high ceiling grosh's  and no two post lifts .....wutt up!?!?!?......oh that's right you bought the SaaB

wae PowerDork
2/21/23 10:49 p.m.

Focusing on the fuel pump, we started out the evening by going out and getting 4 5 gallon gas cans into which to pump the tank of really old bad gas.  What's insane is that Home Despot wanted $27 for a 5 gallon can while Menards was a more-reasonable $17.  Back at the shop, we took the trunk floor out and got to pumping:


While I was promised a mostly full tank of bad gas, I only got about 5 gallons.  That was a win for sure!  With the gas out, it was time to try to swap the pump.  The old was pretty grody:

Some denatured alcohol and a little bit of vacuuming got things a bit better.

In trying to put it all back together, though, it appears that there's some part of the assembly missing.  The pump fits in to the strainer, and then the strainer goes in to the pot, and then the lid snaps on.  But then the pump and the strainer just sort of bang around in there.  And there's nothing preventing fuel from going around the top of the strainer.  There's got to be some sort of ring that hold it together and seals it up.  I think I'm going to need to go find a full assembly and return the bare pump.  Oddly, all the aftermarket assemblies also include the fuel lever sender, but that's not how this car is set up - the sender is totally separate and uses a different hole in the tank.

therealpinto GRM+ Memberand HalfDork
2/22/23 2:35 a.m.

Cool project and make sure your daughter gets to drive it. It is worth it...

I am no Saab guru at all but I know that there are different versions of fuel tanks and fuel pump baffles. Back in the early 2000's when people here in Sweden actively tuned these turbos, I know that an earlier tank and pump baffle was desireable since it had the "old style" Bosch pump, meaning you could fit a Bosch 044 or 040 pump.

I am 99% certain that version was the one with the separate fuel level sender, since I was given a complete 900 tank and pump baffle for the "small" pump (for possible use in a Capri) from a guy who swapped tanks to be able to use the  040 pump. The baffle I still have somewhere has the fuel level sender.

So, maybe you just need the old style Bosch pump? That is a larger diameter that probably fits your baffle.


Powar UltraDork
2/22/23 8:35 a.m.

I have whatever you need for the fuel pump assembly. It came here complete and it should've left that way. Send me a pic of what you're working with and I'll sort it out.

wae PowerDork
2/22/23 9:28 a.m.

In reply to Powar :

Cool, thank you!  I'll shoot you an email with the pictures of what I think is missing, but if it's lost to the sands of time, it's no big deal.  It's also possible that I'm just not seeing it right - I've tried looking at every picture of the fuel pump assembly I can find but nothing really shows this part.

The fuel pump itself fits perfectly in the screen, it's just that it seems like the screen will just sort of bang around in the canister.  And there are some tabs or grooves in the screen that meet up perfectly with the edge of the pump, but they leave gaps between each ridge.  It just really looks like something should snap in there, you know?  And fear not for my daughter: she will get to drive it basically as soon as it's running, has tires, is registered, and on the insurance!

TheMagicRatchet New Reader
2/22/23 11:31 a.m.

I haven't been inside on of those in a very long time so my memory is fuzzy but isn't that system supposed to have a pre-pump? Perhaps that's what's missing from your cannister. I'd have to get out the parts books but I think the consolidated unit (with the sender) came along later. 

re: #7 - The ignition switches (and locks) usually failed from dirt falling into them from the console. It is possible you just need a good cleaning. 

Lou Manglass

wae PowerDork
2/22/23 11:46 a.m.

In reply to TheMagicRatchet :

No, it looks like it might just need a rubber isolator or something like that that maybe. 

I am fairly hopeful that the switch problem is either some gunk or a bit of carbon buildup.  It doesn't look like a very complicated bit of kit, so assuming I can open it up in some way that I can also put it back together, I should be able to rebuild it.  I found a YouTube video of someone repairing the mechanism where it won't spring the key back from the start position and since this switch is exhibiting that behavior, I can start there!

MiniDave Reader
2/22/23 12:47 p.m.

What do you do with the old varnishy gas you drain out of the tank? I have a car I need to drain and I don't know what to do with the old gas.....

wae PowerDork
2/22/23 12:56 p.m.

In reply to MiniDave :


I haven't figured that part out yet.  I was going to check around with my county's public works dept and see if they have any ideas.  I was also wondering how bad it would be to mix a gallon of the old gas in with an otherwise full tank of fresh gas and just burn it up that way.

While I would never do this ever, it might also work as an effective weed killer.  Say along a fence line so you don't have to tear up your trimmer line on the fencing wire.  But I would never do that.  Ever.

eastsideTim UltimaDork
2/22/23 9:12 p.m.
MiniDave said:

What do you do with the old varnishy gas you drain out of the tank? I have a car I need to drain and I don't know what to do with the old gas.....

My county's maintenance department was willing to take old gas I drained out of a project.  They also would take coolant.

OHSCrifle GRM+ Memberand UltraDork
2/22/23 10:41 p.m.
MiniDave said:

What do you do with the old varnishy gas you drain out of the tank? I have a car I need to drain and I don't know what to do with the old gas.....

I've never done this but I remember reading once that gas will evaporate if you leave it in an open container. Just don't toss a cigarette in there in the meantime. 

can anyone else verify this?

procainestart SuperDork
2/23/23 2:03 a.m.

In reply to TheMagicRatchet :

Saab went to a single Walbro pump in '90, so no pre-pump.

@wae - if you aren't able to fix the ignition, you can make a simple bypass with a few wires and start the car from in the cabin. Takes 10 minutes. Lmk if it comes to that til you can get another switch. You can also start the car under the hood with a paper clip... 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
2/23/23 7:49 p.m.

I generated about 30 gallons of bad gas from my '81 before I found a fuel tank that wasn't full of red goo.  I always just dumped it in the waste oil containers at work.  People would drop off old gas for disposal all the time, so this was no big deal.

It probably won't evaporate.  All the stuff that can evaporate easily has done so already, which is why the once full tank had less than five gallons in it smiley

Powar UltraDork
2/23/23 7:55 p.m.

@wae: I dropped the package at the post office today. Should be to you VERY quickly, I'd imagine. 

wae PowerDork
2/23/23 8:11 p.m.

In reply to Powar :

Thank you so much!  I greatly appreciate it!

wae PowerDork
2/26/23 2:29 p.m.

The canister parts arrived yesterday - thank you again! - and we got them all installed this afternoon:

But since it's me, I naturally took one step forward and two back.  I accidentally connected the supply line before I put the lock ring on.  When I went to carefully remove it - and I was extremely careful - the stupid plastic line snapped.  Grr.  So now I've stopped the tank and removed the line from the fuel filter and got the line out.  Now I've got to figure out a new fuel line for it.  Doh!


Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
2/26/23 3:21 p.m.

Nylon line compression fitting, or press in splice.  Anyone that sells SURR will have one.  They are made specifically for joining two pieces of Nylon fuel line.

wae PowerDork
2/26/23 5:30 p.m.

In reply to Pete. (l33t FS) :

The whole line was so brittle I was a little bit afraid to try just patching it.  For about $21, I got a 10' roll of nylon 5/16 fuel line that's much more flexible and less likely to snap on me. I went ahead and got the old line off the fittings and put the metal banjo fitting that goes to the fuel filter.  After the daughter is off work, we'll go back out and route the line, trim to fit, and attach the fitting that goes to the canister.

wae PowerDork
2/26/23 10:52 p.m.

We ran the new line, got the canister screwed down, and found an old battery to stuff in there.  I'm not sure if the battery is really good enough to use long-term, but we hooked up jumper cables and got power through the car.  As best as I can tell, the "drive" position of the ignition switch is all the wires tied together except for the red/yellow (or yellow/red? I don't remember) which is the starter relay wire.  We were able to get it to turn over, but it wouldn't start.  I do not think the fuel pump is getting power because when we hooked up power to put the car in its ignition key on mode, I did not hear any noise from the pump.  A test light on the fuel pump connector remained dark as well and the multimeter showed a few hundred mv while cranking.

With the battery hooked up and all the ignition wires separated from each other, there are a couple dim warning lights on the gauge cluster, so it seems like something is getting back-fed somewhere.  I'm wondering if there's a bad ground.

Time to get the wiring diagrams and get to work, but it was getting pretty late so we called it a night.

wae PowerDork
2/27/23 8:36 a.m.

Since it was pretty late last night, we didn't really do any troubleshooting other than looking at the fuel pump leads with a multimeter before closing it up and calling it a night.  Over coffee this morning, though, I started reading through the electrical diagram and fueling system sections of the service manual.  One clue might be that the fueling section says that the low-fuel light should illuminate at about 10 quarts of fuel.  I put in a little more than 5 gallons last night - and verified that it all went into the tank and not the floor! - so that should be more like 40 quarts.  But when we were giving it power last night, the low-fuel light was on.  According to the service manual, the fuel level sender and the fuel pump share a ground.  That ground is also shared with the tail lights, however, it is not shared with the courtesy light in the trunk.  Or at least it isn't listed in the service manual.  While I know that the courtesy light was working, I have no idea if the tail lights were on.  So if that ground is bad, I could definitely see why the fuel pump and the fuel sender were not working.  So, something to check out.

wae PowerDork
3/2/23 10:37 p.m.

With the battery charged up a bit more, the whole brake fluid level light thing isn't happening any more.  Weird, but okay.  I'm going to assume that was an artifact of having low voltage and not worry about it for the time being.

The remainder is basically notes for myself:

Power flow for the fuel pump goes from the battery to pin 30 on the fuel pump relay.  There's a fuse there that doesn't appear in the wiring diagram as far as I can tell.  From the other side of the relay socket, power flows across the car to fuse #30 in the left side main fusebox.  From there, power flows through the car back to the trunk and to the pump.  The pump is grounded at earthing point #9 which appears to be in the back.

Bridging the fuel pump relay did not turn the pump on. 

Fuse 30 has continuity.

Pin 30 on the fuel pump relay socket has battery voltage.

With the battery disconnected, the fuel pump disconnected, and the fuel pump relay disconnected, there is continuity on the connector in to which the fuel pump plugs.  Maybe it's completing the circuit through the O2 sensor heater, though?  That appears to be fed through the same wire that comes from the fuel pump relay in to the fusebox.

Despite the wiring diagram showing that the same GR/RD wire that is present at the fuel pump should also be present at the relay, there is no GR/RD wire at the relay.  But it wouldn't be the first wiring diagram I've used that had colors wrong.

The fuel pump relay pin 86 is fed by the main relay and then grounded by pin 20 on the ECU.

Found a Saab Guard alarm control module under the rear seat.  I don't think it has an immobilizer, but I need to find some 1990-specific information to make sure that's not my problem.


I need to check voltage when cranking between pins 85 and 86 on the fuel pump relay to verify that the ECU is commanding the fuel pump.

If no voltage there, check continuity between pin 85 on the relay and 20 on the ECU connector.

Pull fuse 30 and check for continuity on the fuel pump connector pins.  Should be open there. 

Check continuity between fuse 30 and the +12v pin on the fuel pump connector.  If that's open, there's a break in the wire somewhere.

If that's good, pull fuse #1 and check continuity between the other side of fuse 30 and pin 87 on the fuel pump relay.



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