Fuel leak (or, this can't be good)

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17 Jan 2012 15:48 #7818 by Avid928
Fuel leak (or, this can't be good) was created by Avid928
Discovered my '83 928S dripping gas from under the tank. (Glad the exhaust routes well to the other side!) Leak is most noticeable (obviously...) just after parking, and seems to stop after several minutes. Started to pull the tank cover the other day but quickly realized I was getting into more of a mess than I had time for. I see from maintenance records the previous owner had the fuel pump replaced three times over about ten years and 50K miles. Seems unusual to me. Any educated guesses where the leak is before I dig in again, or tips on removing the tank cover without dropping the whole tank?

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17 Jan 2012 16:57 #7819 by 928mac
Replied by 928mac on topic Fuel leak (or, this can't be good)
Hi Avid928, whats your name, you should put it and your car in your sig for future referance to repairs.

So lets localize where the leak is coming from, at the tank to nipple hose, or at the pump to tank hose, or at the pump to filter hose.

I chased mine for a while and found it was leaking at the electrical terminals to the intank pump. If yours is the same I have a fix for that also.
If you have a compressor and a air line to blow it off, it will help see the exact place it is leaking. Take a picture and post it of the area and we will take it from there.

Brad

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17 Jan 2012 17:35 #7821 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
The fuel output is from the tank to the pump then up to the filter then to the engine bay. The return fuel line is at the top of the tank where the fuel level sensor wires are.

Given the fuel pump has been changed too many times id start there. theres a metal S line that goes from the pump to the filter that has banjo bolts with copper sealing washers as theres a pressure valve.....see pic:

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17 Jan 2012 19:32 #7822 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Thanks to both Brad and Malcolm for your quick replies. My name is Brian, sorry I didn't include that. Been a 928oc member for close to a year but this is the first time I've tried to post anything, or even check the forums much for that matter, so new to the etiquette. Car is an '83 928S, one previous owner, a trusted friend who left me with pretty complete records, at least back about fifteen years.

The gas tank cover has a hole in about the middle, a drain I presume, and that's where I see an actual drip for a few minutes after shutting her down. It's a bit wet a few inches around that. I started to remove the cover a few days ago, but realized the whole tank (which I had filled not long ago) was coming down with it. I was running out of time, so pushed it back up and thought I'd try to get educated a bit before proceeding further, thus my post.

The shop manual says, when replacing the fuel filter, to "Take cover off of fuel tank at bottom" but it doesn't mention the whole tank will come down on you as a result. It appears to be in two pieces, so maybe I started with the wrong half (front). I do have a compressor, so will be able to clean things up once I get it uncovered.

Hopefully just a loose clamp or something, given the strange frequency of fuel pump replacements in the past, or is that something of an Achilles heel on this otherwise amazing ride?

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17 Jan 2012 19:44 #7823 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
first, glad to see you posting here and more important 'DONT DRIVE THE CAR'

not sure what is meant by removing the cover?

to confuse matters more some 928s were fitted with a intank pump as well as the regular external pump. If you look closely at the pic you can see the routing of all lines near the pump and filter. Post a pic if you can.

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17 Jan 2012 19:58 #7824 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Thanks again, Malcolm. I'll have to wait for my girlfriend to get home to post a pic. I'm pretty techno-ignorant. She's the computer wiz. The cover I'm referring to is a big, maybe two-piece, plate under the gas tank, with four arms extending upward to bolt the whole thing in place. From what I can gather from the shop manual, if I'm successful in removing it I'll find the fuel pump and filter nestled within next to, and under, the tank. Just didn't get that far yet. Seems you ought to be able to access the filter and pump without dropping the whole tank on yourself, so I must have been doing something wrong. Appreciate any help!

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17 Jan 2012 20:03 #7825 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
ah ok, got it.

The cover is just that and does not support the pump,filter or tank. Remove the cover and all shall be very evident :)

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17 Jan 2012 20:20 #7826 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Thanks. Just looking at the shop manual again (rather fuzzy print out from a disc I bought - Workshop Manual 928 1978-1994, section 20, page 2) and it looks like half the cover removed, exposing the pump and filter. Hard to say which half, front or rear, from the picture. I must have been unlucky and started to remove the wrong half, as the tank was definitely headed in my direction (under the car)!

PS I did drive the car after I pushed the tank back up because it appeared to no longer be leaking, but was dismayed to see, upon arrival at my destination, it was leaking more than before. Drove home with no ill result. Could this be because of the "accumulator" (or "pressure resevoir" - part #4 on section 20 page 6)? I really have very little understanding of this fuel system. Maybe there's still pressure when you shut the car down but it bleeds down after a few minutes?

PPS Girlfriend is home but I doubt I can convince her to climb under the Porsche tonight!

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17 Jan 2012 20:50 #7827 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
ok........I truly hope you now have the message and dont drive the car. If you ever read Rennlist a guy and his daughter got out of a firey 928 which then burned to the ground. the guy, like you, had been working on the fuel system.

the system does hold pressure long after shutdown, in fact, the spec is 80% of operating pressure after engine off IIRC/

I have a pic of the system from a car I worked on last year with the cover off:

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17 Jan 2012 21:10 #7828 by 928mac
Replied by 928mac on topic Fuel leak (or, this can't be good)
This was mine last year

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But when I have trouble I have two experts that I can call for help

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17 Jan 2012 21:21 #7829 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Thanks for the pics, guys. Looks just like I imagined, but mine's still covered. Does make it look more like the cover I need to remove is the aft section of the plate I referred to.

Malcolm, indeed I have no intention of driving it again until I get this resolved. Thanks for your concern.

Still hoping it's just a loose clamp or something simple. Do these tanks ever develop cracks? Sure hope not...

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17 Jan 2012 21:37 #7830 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
the tanks are plastic and are known to leak where the output fuel line is fastend.

where you live? we need to escape the frigid weather:)

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17 Jan 2012 21:44 #7831 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
I'm n NC. 65 today but about to plummet. I don't have a heated garage, in fact no garage at all really, so nice to have the occasional day when you can get a bit of work done outdoors even in winter. Talk about your proverbial "shade tree mechanic"! Where are you freezing?

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17 Jan 2012 21:50 #7832 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
both Brad and I are in alberta where its currently -30C and lower.

65F is a +50c temp change...........luxury

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17 Jan 2012 22:30 #7834 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Wow...and ouch. Actually hadn't even occurred to me the 928oc was international! Explains your "parked for the winter"! Well, stay warm, and thanks for all the advice. I'll try to dig into that fuel leak in the next couple of days and will keep you posted.

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17 Jan 2012 23:27 #7835 by 928mac
Replied by 928mac on topic Fuel leak (or, this can't be good)
This is looking out my front door

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21 Jan 2012 09:04 #7853 by lrpman
Replied by lrpman on topic Fuel leak (or, this can't be good)

This was mine last year

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But when I have trouble I have two experts that I can call for help

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Brad I HOPE the experts are not trying to work on the engine on the 911 :D But in there case WHO CARES just enjoy the effort.

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21 Jan 2012 14:04 #7857 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
Hey Brad, Malcolm, and all,

Mid sixties (F) in NC today, but again forecast to plummet tonight, so I'm trying to work quickly. The cover was way too easy to remove once I realized it was just that back half, and held on only by two nuts, and the front edge slipped under the front plate. The leak is pretty obvious (unless there's more than one). It's definitely dripping at the connection on the fuel pump (the "S" tube that goes to the fuel filter). Everything feels tight, in fact, I can't get the big cap nut off without pushing harder than I want to. When it does start to turn, the inner nut turns with it. I'm off to the parts store to get a big enough flare nut wrench to get on that inner nut (my collection stops at 17mm). With everything so tight, I wonder if the last guy to replace the fuel pump didn't use new seals. Anybody know the size, as I'm headed to the parts store? I presume they're just standard copper washers, not some special Porsche part. My shop manual only calls them "seals", no size or part number. Can't get one off yet to take with me.

Any chance those two "experts" could come down and lend a hand? I don't care which end they think the engine is in!

Brian

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21 Jan 2012 14:23 #7858 by Avid928
Replied by Avid928 on topic Fuel leak (or, this can't be good)
PS Any chance any of the threads in the fuel system plumbing are backwards? I don't want to go yanking on them too hard until I know!

Brian

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21 Jan 2012 18:58 #7859 by 928mac
Replied by 928mac on topic Fuel leak (or, this can't be good)

PS Any chance any of the threads in the fuel system plumbing are backwards? I don't want to go yanking on them too hard until I know!

Brian


No I don't think there are any left hand threads there.
I think they are all righty tighty, lefty loosy. :D

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21 Jan 2012 19:21 #7861 by the flying scotsman
Replied by the flying scotsman on topic Fuel leak (or, this can't be good)
Sorry, the 2 experts are keeping us warm :)

Its common for the 'S' pipe between the pump and filter to twist and fracture when attempting to remove. Use the correc sized flare wrenches and it will come apart.

The sealing washers are copper so if you cant find replacements they can be annealed. If you dont know how let us know. BTW they are 12x16 (mm of course)

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24 Jan 2012 10:32 #7901 by Adamant1971
Replied by Adamant1971 on topic Fuel leak (or, this can't be good)

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I have a plug to fix that leaky rear end!

1987 S4 5 spd, LSD, Sport Seats

Daily Driver: 2008 SAAB 9-5 Aero CombiSport

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