[f512tr]

Does anyone know how to remove and reinstall the fuel injection rail on an S4 Spider? Specifically The repair manual says to cut the short fuel hose between the rail and the injector but is vague on how to reinstall them. Has anyone ever done this? Also any idea how to remove a stripped out socket cap screw holding in the injector? Are these actually in the manifold so if I remove the whole manifold I can drill it out? Lastly I know the fuel is under pressure; how do I release the pressure safely or is this not an issue? Thanks very much if anyone knows how to do this.

 

[Tifosi]

Pressure relief:

Usually if it sits long enough the pressure will bleed down by itself, however, if it doesn't or you don't want to wait, you can crack loose the regulator nut where it tightens to the rail. Go slow, and wrap a rag as it'll spew a bit if there's any real pressure.

Rail:

If you're going to replace the short lines between rail and injectors, then all you need do is unhook the regulator, the feed line and the support bolt that's in the middle of the rail. Cut the short lines in the middle and the one that feeds the cold start injector (Motronic has one of those, right?) then pull the rail off.

Even though the book says to cut those little washer thingies on the ends of the short hoses, don't, use a soldering iron to cut/peel the rubber away and save the washers as you can re-use them with the new line (provided you get the correct size, otherwise you'll have to get fuel injection specific hose clamps and not use the washer bits)

The stripped allen head:

You mean the threads or the head?

If the threads, you're in for some work, up to and including either helicoil or having it welded up then re-drilled and tapped.

If it's the socket where the wrench goes, then you might be able to get ahold of it using needle nose vice grips (it's not in there stupid tight) and back it out so you can replace it with a new one. (common size found in most hardware store bolt bins. Take the old one for size and length reference)


Reinstall the rail:

Get all the short hoses onto the injectors first with either the washer thingies or the hose clamps holding then on, then just kinda line up all of those with the nipples on the rail and push it into place. Reinstall the regulator, put a fresh line on the cold start valve, hook up the feed line, re-do the support bolt and fire it up while looking closely for leaks.


That should cover most all of it, and if not mabe someone will trip in and offer some more finite points.

 

[f512tr]

That pretty much covers all my questions so thank you very much. One other thing, is the fuel injection hose anything special or just generic fuel injection hose?

The allen head is stripped at the head. I don't know why but those cap screws were put in way to tight and even using a 5mm allen key socket driver I can't get the screws out. The key has started turning in the head! Any other thoughts? There is no way a plier is going to get the things out with them in so tight and there is no other way to remove the injectors. The injectors are attached to the manifold right? Thus if I can remove the entire manifold I could work on it on a bench.....

Thanks very much
Britt

 

[ghnl]

On the S3 Spider the FI hose (from rail to injector) is 7.5mm. I couldn't find any at a local auto supply store but IAP sells it. 1/4" is too small, 5/16" is slightly bigger than 7.5mm. If you are willing to add a clamp then 5/16" might work. I bought a few feet of the 7.5mm hose from IAP.

Check the business end of your allen driver. If it is not perfect then try a new, quality allen driver. Socket head screws are often hardened steel. If so, then hopefully the allen bolt is OK and your driver is worn. If the head is really worn then drilling it out could be problematic IF it is hardened steel. Tifosi's suggestion is to try a 'needlenose' vise grip - hoping it can reach in and allow you to turn the screw. If you can grab the allen head with the tip of such a vise grip plier, try slipping a screwdriver in at right angles to the plier to give you the leverage to turn the screw.

Good luck...

 

[Tifosi]

Check the business end of your allen driver. If it is not perfect then try a new, quality allen driver.

Or, cut about 3/16" - 1/4" off the end of the existing one to present a nice fresh clean tool.