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Fuel pump replacement

20K views 9 replies 7 participants last post by  jvanabra 
#1 ·
I recently described the process of replacing the older-style roller type fuel pump (1988 and earlier), but the post was deleted during the site migration to the new server.

I've rescued it from the old site, and here it is again:

Ever since I've had my '88 900S 4-door (non-turbo), the fuel pump had been noisy--obnoxious sometimes, then quieting down at intervals.

I expected to have to replace the pump sooner or later, so I nailed a good used one on eBay for about $20 and sat it on a shelf.

Finally, five years and almost 80k miles after I'd bought the car (and the replacement pump), the old pump died. This was at
10:30 pm a few days ago, some 25 miles from home, and with the outside temp. at 18 deg. F (about -8 deg. C). Adding to the evening's enjoyment was the discovery that my cellphone battery was flat :evil:

Incredibly, I had broken down a block away from the only person we know in the entire area--and they were home. The next day, I had the SAAB towed to my driveway (the towing insurance sure paid for itself).

Being an '88, my car has the older-style "roller" pump; from '89, you got the "rotor" type. They are very different.

Either way, checking the pump's operation is as follows: Make a jumper with small male spade terminals to fit the fuse sockets, then remove fuses 27 and 30. With ignition off, bridge the inboard socket of fuse 27 to the outboard socket of 30. The pump should run if it (and the wiring leading to it) is good--you've bypassed the pump relay. Mine? Not a sausage...

Later (rotor) pumps have a threaded collar to hold them in position; the roller pumps are mounted in a rubber funnel secured to a lip on the tank with a really long hose clamp. Here's how I replaced the pump:

(1) Remove trunk floor. Pry up and remove the "coffee-can-lid" pump cover, and pull off the 2 wire connectors.

(2) Forget about Bentley's advice to use a wrench to hold the pump outlet while undoing the fuel line's banjo cap nut; the sealing washer under the banjo prevents any wrench from fitting onto the flats. Instead, clamp large vise-grips onto the banjo itself (opposite the fuel line), then use a 19 mm socket and breaker bar to loosen the cap nut. Start with the vise-grip parallel to the breaker bar, so you get maximum opposing leverage.

Carefully remove sealing washers (you can probably reuse them--I did), and move the banjo and fuel line aside (tie them out of the way with string, if needed).

(3) Pry up the rubber bung covering the access hole, and use a 1/4-in. drive 7 mm socket, universal joint, and extension to loosen the large hose clamp. If the angle is too far off, you may need to drill an access hole in the wall of the spare-tire well (being careful not to drill into the tank, of course--it's plastic).

(4) Lift pump and rubber "funnel" up enough to unclip and pull off the pump return line; stick the end if this line into the access hole to prevent losing it in the tank.

(5) Set the cover plate over the hole, and rest the pump on this; it minimizes fumes coming at you, and reduces the chance of bits and pieces falling into the tank.

Undo the 2 torx screws holding the supply pump to the reservoir, and pull this pump downwards to disengage and remove. Use a 1/4-in. miniature open-jaw wrench (an ignition wrench is good) to undo the 2 nuts holding the wires to the supply pump's terminals. DO NOT just cut the wires and splice them later: These wires live in fuel and/or fuel vapor, and sparking caused by loosening crimp-splices or dissolving electrical tape could ruin your day :eek:

(6) Attach wire terminals to replacement supply pump, and refit this pump to new reservoir (or to old one, if you only had a bad supply pump). Reattach return line to reservoir, and insert entire assembly into tank (note the orientation--see Bentley, page 234-10). Push down on rubber funnel's edge all round, to make sure it seats on lip of tank.

(7) Refit banjo (with fuel line) and tighten nut. Again, use vise-grips to help. Reconnect wires and use fusebox jumper to test pump. If it leaks at banjo, use the vice-grips and breaker bar/socket to tighten the cap nut some more. Re-test with jumper. If all is OK, fit and tighten hose clamp around funnel.

Aside from a soft ticking audible at idle, the "new" pump is totally silent--and I've noticed improved top-end performance as well. Here's to another 16 years/270k miles :lol:
 
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#3 ·
Wow that is really easy! I am still trying to take the pump out of my 9-3, took one day to drop the tank...
 
#4 ·
Ahhh so that's what that plastic line is hooked to in the tank on my 85 the hose is rotted and the return is just sitting down in the tank.....maybe that's why the 2 pumps died.

Now i just gotta find them at a good price, hell the main pump with my employee discount at oreillys is still $230
 
#5 · (Edited)
I tested both the pre-pump (yellow) and the fuel pump with a car battery. The fuel pump ran initially but stopped once I shook it around and then would run again when shaken - out of the car and dry and on a workbench. (not going to chance it, and it would explain my frequent no-start condition with this car.) The pre-pump runs all the time when I tested it.

I'm also shopping a fuel pump. I've found some aftermarket stuff that seems too cheap...not sure i want to go that route, but if anyone has any suggestions I'd be open to ideas.

Now i need to remove the other Turbo pump which has the same non-working fuel pump issue.....
 
#6 ·
I found this write up VERY helpful as i had to change out my pump away from home and as such needed to bring everything i would need with me. My only addition... thankfully i had a very good selection of torx bits with me as the original post fails to mention the size of the ones holding the supply pump on. They are i believe T8, a little smaller than a good deal of torx bit sets include, just a FYI.
 
#7 · (Edited)
Thread revival..... should the fuel pump be exposed between the rubber funnel and the pump receiver bucket (see attachments)? Per bentley, the fuel pump should be clocked so the yellow positive terminal faces the front of the car. It also states for LH injection the rubber funnel should slide onto the pump 42mm (give or take 2mm).

The pictures in the bentley appear to show the pump exposed but ive also seen some pumps online with no pump exposed. Which is correct? Im sure this impacts where the strainer at the bottom of the pump sits in the bucket.

Additionally can anyone confirm the return valve going back into the tank is a one way valve? Is a one way valve from a 9-5 the same?
 

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#8 ·
You have two things going on there - the check valves are only for the '90+ cars and are not applicable to the early pump you have. IME don't rely on Bentley's 42mm number as it only applies to some years and I couldn't tell you which. You will need to measure your old pumo, measure the new, and position the boot in the same way. If you don't, the strainer will be too far off the pump floor and you will run out of gas before you're actually out.
 
#9 ·
Good point... unfortunately I installed the pump last time and at the time I really didnt follow the bentley at all so it was probably not installed correctly. It seems like I have had fueling issues with this car since ive purchased it. I would like to rectify it now with this new pump.

So how far from the tank floor should the receiver bucket/pre pump sit?
 
#10 ·
IIRC there is a relief for the prepump strainer in the bottom of the fuel tank, and you need that strainer something like 2-3mm off the floor of the relief I think. I think there is a spec in the factory manual as I think I used it when installing an '87 pump in my '80's tank. It's really annoying to do, as positioning that boot on the main pump is fidgety at best.
 
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