AN hoses and fittings for the fuel lines

[backdated]

This stuff connects the long, underbody fuel lines to the short pipes mounted on the engine.

Apart from the the fuel filter and TBI adapters (the black aluminum parts), the components were acquired from Dunlop Hiflex. These guys were quite helpful, I just gave them my crappy pencil drawings and they assembled the correct hoses and fittings for me on the spot.

Assembled:

Fuel feed line: top right-to-left, counter clock wise

• Vinyl(?) gasket, replaced w/ Teflon
• Aluminum adapter: TBI (14x1.25mm) to AN-6
• Hydraulic hose assembly: AN-6 / ??mm teflon hose / AN-8
• Fuel filter: AN-8 / AN-8
• AN-8 to ?? thread adapter 
• Compression fitting for 10mm pipe w/ ?? thread
• 2x Compression fittings for 10mm pipe
• Compression fitting for 10mm pipe, barb fitting for 10mm hose

Fuel return line: bottom right-to-left, counter clock wise

• Vinyl(?) gasket, replaced w/ Teflon
• Aluminum adpater: TBI (12x1.25mm) to AN-6
• Hydraulic hose assembly: AN-6 / ??mm teflon hose / ?? thread
• Compression fitting for 8mm pipe w/ ?? thread
• 2x Compression fittings for 8mm pipe
• Compression fittings for 8mm pipe, barb fitting for ??mm hose

Russell 640813, 640803 TBI fuel line adapters

After a logistical hassle that shouldn't happen in 2012, I got the necessary fuel line adapters for the GM (Rochester) TBI unit:

• Russell 640813: male 14x1.25 mm (14 mm thread w/ 1.25 mm pitch) to male AN-6
• Russell 640803: male 142x1.25 mm (12 mm thread w/ 1.25 mm pitch) to male AN-6

However, the hydraulic shop informed me that the white seals these fittings come with are a kind of vinyl material that isn't E85 compatible. I'll need to get replacements for those, apparently out of Teflon (PTFE).

They're not O-rings, but a straight cylindrical shape instead.

The original fittings have a wedge that holds the seal in place, and the original seals have a slightly conical(?) shape that makes them snap onto the end of the fitting.

Tiivistekeskus didn't stock this kind of seal, and their sales person wasn't very optimistic about finding one either. Apparently they don't have verified information about combined gasoline and E85 compatibility of their materials, and weren't prepared to make wild guesses either. They could "lathe" custom PTFE (Teflon) gaskets according to measurements, at an approximate price or € 50 apiece, though.

Seal dimensions:

All measurements are in mm.

E85 Fuel Filter Choices

The stock fuel filter also uses those pesky GM flared connectors, so if I wanted to use one, I'd have to use those repair pipe kits on both sides of the filter and connect them up with some ugly compression fittings - not a very clean solution. Also, there are no guarantees that the stock filter (which would have been a Wix 33481) can withstand E85 fuel.

According to the service manual,

[a] fifteen micron fuel filter is used in the fuel feed pipe ahead of the fuel injection system and mounted directly in front of the rear axle. The filter housing is constructed of steel with threaded Fittings at both ends. The fittings are sealed with O-rings. The filter element is made of paper, and is designed to trap particles in the fuel that may damage the injection system.

This should apply to all engines (3.1L, TBI, TPI).

So, at least a 15 micron filter is required, and it should somehow connect to the AN plumbing that will be used at the TBI unit. A reasonable price and availability of replacement filters / elements would also be nice. The Wix filter is even rated at 4 micron.

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I actually sacrificed two days from my life trying to find a suitable filter. The local supplier's knowledge and/or motivation on this matter proved practically non-existent, and the manufacturer's specs aren't always clear either.

The Fuelab 8183X series have male AN fittings and use a disposable, 6 micron, fiberglass, E85-compatible element. This would seem optimal, but a bit pricey. They go for around €140 at turbozentrum.de, and replacement elements are about €33. 

Summit Racing sells filters by Russell performance with 10 micron paper elements. Filters go for around $75 (about €130 including delivery & customs), replacement elements for about $23. Only Summit and a random magazine article claim that they're E85 compatible; Russell's own web pages or catalogs don't mention it at all.

The Magnafuel inline filters claim Ethanol compatibility, but the marketing text is ambiguous. The filters have metal elements down to 25 micron, and the 10 micron model has a paper element. The chapter where the compatibility claim is made refers to a "[choice] between 75 and 25 micron filters", and the 10 micro model only appears in the product listing. Their PDF catalog has the same text, but doesn't list the 10 micron filter at all. One could read this either way; I'd rather not reward such ambiguity.

The SX Performance 41002 is available for $91 and includes a 10 micron paper element, but the brand seems a bit obscure -- how long will replacement elements be available?

AES Performance sells an element w/ NPT fittings for $50 on eBay. Cheap, but likewise a small company.

Finally, I went for a Golan "40 - Large" filter,  $85 from Jay Racing. Express Mail International shipping was $59,40, total w/ VAT & customs will likely be around €150 ($185). It has AN-8 fittings (AN-6 was out of stock) and a washable metal element, and the company's propaganda was convincing enough. Here's one installation (scroll down to bottom), and some people having (scary) issues w/ the Golan filter. Hopefully these are just, eh, individual cases.

There's some generic talk on E85 filters here and here.

Also, there are 40 micron filters available for $19 at anfittingsdirect.com with a cleanable, reusable bronze element, suitable for pre-pump use.

Replacing the fuel lines (4)

(backdated)

 Removing the Engine Fuel Pipes (2)

The easiest way to remove both engine fuel pipes is to remove partially remove the generator and the obstructing pipes and cables -- no need to touch the valve cover like I did earlier.

The belt loosens simply by twisting the tensioner device.

The generator is attached with two bolts (Torx 45, Torx 50) in the front and a nut (10mm?) in the back. It's not necessary to completely remove the bottom bolt; when loosened, it'll work as a hinge over which the generator will swivel.

Top-front bolt: 25 Nm
Bottom-front bolt: 50 Nm
Bracket-to-generator nut/bolt in the back: 25 Nm

Fitting in new underbody pipes

Dirt cleaned up from where the pipes will go. Some cavity wax was applied on the body too as a stop-gap measure. The whole paint job should really be redone & new chassis protector goo applied in the bottom.

Although the old pipes were flexible enough that I could pull them out in one piece, it wasn't possible to put the new hydraulic pipe, 1.0 mm wall thickness, in the same way. I decided to cut them in the front and reconnect them using compression fittings.

This allowed me to bend the "final mile" outside the car. Unlike most of the plumbing, I'm actually satisfied with this piece.

Replacing the fuel lines (3)

Pipe Fittings

I put the carriage before the horse. Getting compatible fittings, adapters etc. should have come first.

My original plan was to aim for maximum compatibility & originality -- simply recreating the car's original configuration, but with E85-compatible materials. This would mean replacing the body-to-engine feed and return hoses in the engine room with identical parts, getting the flared "screw" fittings fabricated onto the pipe ends, and replacing all O-rings. It turns out this wasn't so simple after all.

Apparently the "flared end + thread" fitting used in the fuel lines is a GM-specific thing, and fabricating it onto a raw piece of pipe requires a special tool.

This fitting is found in

• Fuel feed line, 
• between level sender assy and rear body pipe
• between rear body pipe and fuel filter intake
• between fuel filter exit and front body pipe
• between front body pipe and body-to-engine hose
• between body-to-engine hose and engine pipe
• between engine pipe and TBI unit (adapter)
• Fuel return line,
• between TBI unit (adapter) and engine pipe
• between engine pipe and body-to-engine hose
• between body-to-engine hose and body pipe

All other hose-pipe fittings use simple clamps.

I've queried American Service, South West Trade, US Parts, Metro Auto, Specialty Engineering and Hydromarket whether it was possible to fabricate the male end to an existing pipe, or if  any kind of adapters to either the male or female side of this attachment are available. No-one seems to even know about such adapters, and the the repair shops don't have the equipment to create the flared pipe ends either.

For the record, a GM Fuel Line Flaring Tool Kit goes for between $203 and $360 in the US, so I'm surprised that even reputable shops don't have them.

The TBI Fuel Pipe Fitting

Finally, I noticed that the connectors at the end of the Throttle Body are different. This will at least allow me to attach something to the throttle body. The pipes that run along the engine block do have the GM-specific connectors in both ends, but they attach to the TBI via these adapters:

Left: fuel feed pipe adapter. The male thread is apparently an M14x1.25 (measured diameter 13.7 mm, thread pitch 1.25 mm)

Right: fuel return pipe adapter. This seems to be an M12x12.5 thread (measured diameter: 11,8 mm, thread pitch 1.25 mm).

Notice the white plastic(?) ring at the end of each adapter. They probably work as seals, so simply screwing an adapter with the same thread, but without the seal, wouldn't suffice.

The behind of the Throttle Body, w/o the adapters. Fuel feed pipe on the left (exposed), fuel return pipe on the right (covered in duct tape):

It was impossible to get useful measurements of the available space around the ports, so after carefully removing dirt from around the TBI unit, I screwed it off from the intake manifold and took it shopping. It's attached with three bolts, left, right and front.

The TBI unit removed:

The intake manifold exposed. Engine oil was coming out of the TBI bolt hole on the driver's side. In this pic I had also removed the fuel return pipe, and the fuel feed pipe is loose on the right side (details below).

After a few iteration around the shops, a helpful sales rep at US Parts managed to find adapters that fit the female threads in the Throttle Body. The adapters then let you connect AN system hose fittings and hoses, specifically size AN-6, which means a hose inner diameter of 6 * 1/16" = 3/8" = 9.525 mm. The original fuel feed line was probably 3/8" as well.

The magical pair of adapters in question is one of Russell 640813 and 640803 (black, anodized) or 640800 and 640810 (blue, nickel plated). The black ones were ordered and should arrive in 1-2 weeks.

More on pipe fittings (Wikipedia): Compression_fittings, Flare_fitting, AN_thread, National_pipe_thread

Removing the Engine Fuel Pipes (1)

Since I'll be connecting hoses directly to the back of the TBI, the engine fuel feed and return pipes are redundant. Due to their shape and the flared ends, the pipes can't simply be pulled out though. The easiest way to remove them would be to split them in half with a pipe cutter, but I simply can't bring myself to destroying original components that are still in fine usable condition. So, we'll disassemble parts until they come out.

To get the fuel return pipe out, I had to remove

• PCV filter and hose (attach to the driver's side valve cover)
• Brake booster vacuum pipe (front of TBI / intake plenum)
• The 3 throttle cables attached to the side of the TBI (throttle pedal, cruise control and ??)
• Positive cable at the back of the charger
• Upper coolant hose
• Driver's side valve cover

Even then, it's too tight between the charger and the rocker box to get the thicker fuel feed pipe out. There are some nasty scratches on the pipe already.

... more to follow.