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•8mm vs 6mm Pt 3 Posted by Justin VanAbrahams [Email]  (#32) [Profile/Gallery]
(more from Justin VanAbrahams) on Fri, 4 Nov 2016 12:38:40
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I actually started work on my fuel tank/pump swap this week. Subject is an '85 SPG. Its fuel tank is out, and a tank from a 1990 900T is in. Fits perfectly, but you do need to swap the straps as well as they are of a different height. Not a problem.
The pressure line from the pump is short and just goes to the filter, so that's a discrete piece that's easy to swap. The return line is a single piece from tank to rail and I have zero interest in doing that job, so I'll use the Dorman 180-191 to make a union somewhere under the back seat.
The '90 tanks obviously use the single in tank pump with plastic bucket. I know the stock 900 - and certainly the 9-3 and 9-5 pumps - will flow plenty for any power my '85 is ever going to make (SAVE THE TRANSMISSSIONS!), but long term it's easier and cheaper to use the commodity Walbro 255lph pump instead of a *somewhat* Saab-specific pump, so that is part of this task.
The 255lph pump is about 3mm larger in diameter and 6mm longer in length than the stock Saab pump, and it has an 8mm outlet vs. the more common 6mm outlet. However, Saab sold replacement pump assemblies in the mid '00s that had 8mm pumps and these can be had on the used market. They are identifiable by a Delphi part number and a white vs. yellow bucket. Having one of these 8mm pumps makes the 255lph swap much easier. More on that in a second.
The extra diameter isn't much of a problem. The filter basket that holes the bottom of the pump can be readily clearanced with a file so it fits. There is an o-ring to seal the filter involved here, and I have not worked out whether it will be used or not. On the table is getting it to fit or gutting the factory filter and using a replaceable sock on the filter inlet as Walbro intended. We'll see how that goes. At the top, the factory pump is braced by a rubber bushing, but this bushing will not fit on the 255lph pump without being ripped to shreds. My solution here was to cut away the inner part f the bushing and use foam fuel pump insulation *designed* for the Walbro pump from here:
http://apeusa.com/html/kits.html
The "medium" foam allows the pump to nestle comfortably in what remains of the rubber bushing - should help quiet the pump and bit and adequate isolate vibration.
The extra height is not a problem, and is actually helpful. When removing the factory pump from the assembly, you can just cut the plastic fuel tube around the first (top most) barb, shortening it by about 6mm *and* leaving a slightly flared line to make it easier to fit onto the new Walbro pump. This prevents the factory tube from having to be bent or stressed on reinstall.
Because the basis of this is an "special" replacement pump, you can either reuse the plastic fuel tube as it's already 8mm, or you can remove that section of tube at the tee and use bog-standard 5/16" submersible fuel line and a pair of Oetiker or fuel injection clamps which is a WHOLE LOT EASIER than forcing 1/4" fuel line over an 8mm barb or securing 5/16" fuel line to a 6mm tee! I have ordered some "flexible 5/16" fuel tube" from Summit (#ABT-CFD402) that I am going to try here. It's corrugated and can make some pretty tight bends, and since it's plastic it will *never* fall apart, which can't be said even about submersible rubber hose. These types of tubes are employed on many factory setups these days - there is no worry about durability. We'll see how that goes when they show up on Tuesday.
At this moment, I'm considering this swap solved & done. The only variable is whether I will be successful reusing the factory fuel tube at the pump outlet, or if that fails using the corrugated tube, or if that fails use the least desirable (but *totally* acceptable) rubber hose option. Not worried about that.
The long-term here is that I won't have to worry about the giant rubber boot on -'89 pumps failing and future $50 commodity pump insert replacements. I'm not really looking at this as a performance upgrade, but rather a long-term serviceability upgrade. ;)
posted by 12.195.130...
, Fri, 4 Nov 2016 12:38:40 <-- Viewing This Message, Mon, 7 Nov 2016 09:58:23, Thu, 10 Nov 2016 15:32:45, Thu, 10 Nov 2016 15:33:58
, Sun, 6 Nov 2016 18:51:49
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