924Board.org

[kye]

well, I had an amusing conclusion to my problems last night, so I thought i'd share it with you guys.

it all started with the cold weather and the cars cold start mechanism not working. I read up on it, a friend came over and we checked the switch, and then the cold start valve, concluding this was the problem. no worries, i'll get a new one, but now the car won't start. during testing you turn the engine over quite a bit, so we thought it was just flooded.
next day it wouldn't start either (and my g/f had a migraine with her medication at her house, and my other car that worked was blocked in the driveway by the porsche.. we tried to push it out, but with her state and the uphill driveway it wasn't going to happen!) anyway, I called the RAC (roadside mechanic service) and the guy came out, and we worked out I was getting spark, but the fuel pump wasn't working. he left me with a tow slip, but no resolution. I bridged the terminals on the relay, but it had no effect. I suspected wiring, but my next door neighbour came over, swore a lot and said that it'd be the fuel pump. I wasn't convinced.
yesterday I disconnected the terminals from the fuel pump and used the battery in my other car to give me reliable power and the pump worked.

i'd read the various sections on the fuel pump and the wiring in the haynes, and nothing stood out and it seemed pretty comprehensive, so it was only then that I looked at the wiring diagram and saw the 25A fuse in between the relay and the pump.. you guessed it! the 16A fuse in there was blown. it looked fine, both myself and the roadside mechanic guy looked at the fuses, and neither of us spotted the .5mm gap in the conductor.

anyway, so i've concluded that that's the longest it's taken me (and the most convoluted path to) changing a blown fuse!

also, my question.. to remove the terminals from the fuel pump I had to loosen the bolt for the fuel intake (coming from the tank) to the fuel pump, and move the hard line away from one of the terminals to get the spanner in there. it leaked a little while I had it loosened but stopped leaking when I re-positioned the hard fuel line (I rotated it a little) but as soon as the fuel pump came on it started leaking slightly again. I did it up pretty firmly, but didn't go stupidly tight.
I haven't driven it since, because i'm not sure that it's safe, so there's no risk there.
I suspect that the seal is old and isn't sealing 100%, but what do you guys think? I think the rate of flow is about 1 drop every 10-20 seconds, so it's not much. is there such a thing as a 'small' or 'safe' fuel leak?
I suspect not, but was wondering what happened in the real world with this stuff - i've not worked on cars fuel systems before.

thanks!
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it's funny, but when they said "Anything is Possible", that's exactly what they meant....

[CMXXXI]

You are right, there isn't such a thing as a "safe" fuel leak. The copper or aluminum sealing rings used in the banjo bolts allow for the metal-to-metal seal. I don't know how often they can be used before they lose their ability to do the job. I'd cinch up that fitting just a bit more and see if that will do the trick. Do it a little bit at a time and re-test, as you don't want to strip anything or twist the head off of one of the hollow bolts. You certainly don't want any actual dripping. When the pump is running that 1 or 2 drops per 10 seconds will turn into a small steady stream.

In his recent discussions about refurbishing fuel distributors, I understand Racing to say you can take these copper washers and heat them cherry red with a torch and it will essentially "rejuvinate" them. I've not heard this before, but its worth a try. But take the seal off the fuel fitting before you heat it....

The next time you must go to the dealership for parts, add some of these copper seals to your shopping list. They are a dime or less each. Yes the car needs a variety of sizes in different places, but buying a few now and a few later to have on hand when you really need them will pay dividends (like when removing the WUR and dropping one down on/behind the bell housing...). You'll be glad you did.
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'79 Eurospec 931

[Joes924Racer]

So in essence what hes sayen is you need if anything
remove the bolt at the pump and take off the little copper
washer and replace it and hes right once you loosen them
they wont compress to seal its pretty dangerous to have a
fuel leak. Unless you want to become a fireball.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[kye]

thanks guys.. i'll try by tightening it in little increments and see how that goes. the drop every 10 seconds or so was only with the fuel pump running, so that should be the maximum pressure the lines get to? (ie, car off, pump on).. with the fuel pump off it didn't leak at all.

but if tightening it doesn't work, and I have to take it apart to replace the washer, how do I stop the fuel draining out of the tank through the fuel line?
can I clamp the fuel line? (and potentially crack the rubber hose) or do I have to drain the tank? should be about 40L in there, so that'd be a hassle..

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it's funny, but when they said "Anything is Possible", that's exactly what they meant....

[CMXXXI]

You should be able to just plug the rubber line with a bolt of some sort while the line is disconnected if you are concerned about the possibility of cracking the line. I have a collection of "Caplugs" of various sizes from projects-gone-by that I use to temporarily plug lines with. Just about anything cone-shaped thats close to the right size should stem the flow while you affect repairs. I'm with you, I wouldn't want to drain the tank either. If the line is old, you have a genuine concern about the line cracking, but a newer (pliable) line should be able to be clamped without damage. A bolt in the end may not completly seal it while you swap out the copper washer seal, but it should do the trick "well enough".

As for the other end, the "hard" end where the hollow bolt goes, I don't think you're going to get much out of that end once you disconnect it. I'm guessing it might dribble a little while, but that's about it. Your big concern is going to be the tank side.
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'79 Eurospec 931

[-nick]

FYI- hose shops can rebuild these lines pretty cheaply. A friend had it down in an emergency with an old CIS Scirrocco(sp?) and it cost him something like $20 to rebuild a hose that was $200 new!

-nick

[Smoothie]

Replacing my fuel pump recently, I used a small pair of long-nose Vise-grips with scrap hose pieces over the jaws to clamp the line shut. As far as I know, this was the original 20+ year old tank-to-pump line and it didn't crack. Just feel up the line a bit. You should be able to judge how much squishing it will take by how stiff or pliable it is. If it's stiff and likely to crack, it should be replaced anyway. Based on its' condition, I probably could have reused mine, except that it was a bit too short with the new-different pump and I had the tank drained anyway - so it got replaced with a length of 1/2" fuel line wrapped once around the tank and on to the pump (to avoid kinks). This might only be working for me because my car also has an in-tank pump. (Without an in-tank pump, the OE S-shaped line might be required.)



Tank-to-Pump line <click>
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[kye]

tis all fixed, thank god!

a little bit of tightening has restored the seal.. it took two goes, but it's not overly tight, and it doesn't leak at all, so that's one less thing i've got on my to-do list

thanks for the help guys!
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it's funny, but when they said "Anything is Possible", that's exactly what they meant....