Jfrahm

Hi all,
I've discovered that my 1987 928S4's fuel line, the stub from tank to fuel pump, has literally turned to goo and started dripping. I've got the pump end off and am draining the tank. Is this a straightforward replacement? Once I get the goo out it appears to be. It's the low pressure line secured by a hose clamp at the pump.

I suggest anyone in there for pump or filter service replace this line as it can burn your garage down pretty easily. A compressor or fridge or light switch can spark up those gas fumes. I had a puddle under the car by the time I noticed, glad I was home.

-Joel.

FredR

Good catch- That hose often goes unmentioned for some reason- perhaps it is vulnerable to your fuel mix [ethanol?]. Hopefully you have replaced the regular engine bay culprits as well.

Regards

Fred

Rob Edwards

Yes, definitely a good catch! It is a very simple replacement, especially since you shouldn't have an in-tank pump so there are no electrical terminals to get in the way of tightening the hose clamp on the strainer end. You might consider (while the tank is drained) to partially dropping the tank cradle and popping out the strainer to make sure its screens are clean, but if you have no issues with fuel delivery then it's probably the better part of valor to just leave it all alone.

Perhaps also worth checking the rubber section of the fuel-filter-to-rear-wheelwell hose, while you're in there.

Jfrahm

This low-pressure line seems to be 12mm or thereabouts, I will determine if 1/2 or 7/16 is a good fit.

The wheelwell hose was my next question. This car, my Diamondblau auto, is more or less in storage as I attend to other priorities, I have not done the front-end fuel lines yet but they are on the list. I inspected them in the past and found them to be in pretty good shape but they are on the list along with some AC work, motor mounts, etc.

SeanR

Since you are draining the tank, go the extra mile and replace the strainer seal in the tank. It's is most likely in the same shape as your hose.

Jfrahm

Yes, or maybe it's the leak. The last time I saw goo like this, a metal fuel return nip cracked and the fumes ate the hose from the outside-in.

James Bailey

Be forewarned that the strainer screws into an aluminum threaded ring which is molded into the gas tank but held in place by plastic nubs which fill four small holes in the ring..... over the years I sold many gas tanks to people who put a big wrench on that big nut and managed to strip that ring due to corroded threads. Once the ring spins there is no way to tighten the strainer back up to compress the seal....
Sorry to be spreading fear and negative thoughts.... I just sold a LOT of gas tanks

James Bailey

Also think it is a molded stepped hose bigger on one end than the other.....best to use the right part. One which does not collapse under suction.

Rob Edwards

Perhaps the safer thing to do first is pop the plastic cover over the fuel level sender in the cargo area, undo the level sender plug and the fuel return line, then remove the level sender. You can then have a look at the strainer and the crud in the bottom of the tank without disturbing it.

If you do decide to pull the strainer, you might consider gently tightening (2-3 ft lbs on the screw, max) a hose clamp around the outside of the metal threaded ring molded into the tank. In theory that should decrease the risk of spinning the insert.

Agree with Jim on using the correct molded hose, 928 356 550 05 is sized specifically specific for the strainer nipple for '87-88.

James Bailey

when you pull the level sender....part of the time the X shaped plastic insert at the bottom of the tank sticks to the sender and you end up with it loose in the tank or cut it in smaller pieces to pull out of the tank...not sure of what it's function actually was ????

dr bob

Vortex breaker.

Is it possible to change the in-tank pump and hose though the sender hole? If tha fitting is risky, I'd just as soon go in from the top.

Speedtoys

No.

Jfrahm

Update: I bought the tank seal but due to time constraints I have not installed it yet. It's pretty easy to drain the tank if you are down there and I wanted to stop the leak, move the car and clean up before I had the seal in hand. Since the seal is not leaking I decided to leave it for now.

I ended up using 1/2" ID fuel line of the appropriate spec. The bend is not too bad but if I'd had a unicoil hose bender handy I would have used it, I think it'd be the #13. At that point if you have the time you might as well get the stock molded hose, I believe it is [redacted] for my S4 with no in-tank pump, and hope that it has been updated for the modern fuel additives. The stock molded line is only $20 or so, not a lot more than $4 for line and $12 for a bending spring.

I expected the fuel pump and filter to be full of gunk but I pulled them and backflushed and they were fine. The filter surprisingly so. I guess the gunk was outside the sealed fuel system.

If you pull the S shaped pump-to-filter tube, make sure when it's reassembled that the stub for the banjo fitting does not come loose from the pump, as well it might. It needs to be tight before you put the banjo fitting back on as that can be tightened while the stub stays loose and then... leaks. If I did this again I'd probably locktite that stub to the pump.

You can counterhold that S tube with an appropriate open-end wrench around 21mm. Do not try to loosen or tighten it without counterholding as it looks like it will bend or crack.

When I have time to check the related hoses I will update this thread. Like I saw on my 968 it appears that a small drip that can soak a hose or keep it exposed to raw fuel vapor will sort of melt the outer hose, which in most cases is not rated for full immersion in fuel. When the outer part of the hose softens and melts the hose clamps get loose and then you get a bigger leak.

-Joel.

jcorenman

PET says that the correct hose for '87-88 with no in-tank pump is 928 365 550 05 -- the '04 is for the intank pump on later cars.

As Jim said, the metal inserts tend to spin. They have a knurled outer surface and are insert-molded (i.e. the plastic part of the fitting is molded around the metal part, not bonded). If the threads "stick" then the plastic flexes a bit and the metal insert rotates instead of loosening.

Here's the clamp that Rob mentioned:


The rest of the thread is here: https://rennlist.com/forums/928-foru...l#post11611596

The clamp just reinforces the plastic, and lets the knurling do its job. The o-ring seals against the plastic lip that you can see, and as long as that is reasonably smooth then it will seal. You will need to trim off the four bumps on the outside of the fitting so that the clamp will sit flat, see the previous thread.

I would suggest adding the clamp first, before trying to loosen the strainer. It's a lot easier before the insert spins.

Use anti-seize on the strainer when re-assembling, and don't over-tighten -- spec is 25 NM, about 18 ft-lbs.