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I recently bought a 2003 996 C4S Coupe long-distance and had it transported cross-country. Without going into some of the "surprises" I've found as I wade into the car to correct years of neglect, yesterday I came across a minor fuel leak. It's coming from the top of the fuel pump housing, and while I have access to a factory shop manual and the OEM Parts Catalog, I've not been able to find a general overview of the fuel supply system (i.e., questions such as is it a deadhead system or a full return system, layout of the system with filter and fuel pressure regulator, check valves, etc.).

Any help in pointing me to this sort of information will be greatly appreciated, but going back to my leak, the photo reveals puddling of fuel on the fop of the pump housing. Logic says that one of the two connections is the culprit, but interestingly, neither of these two connections seems particularly tight (i.e., I'm able to wiggle each slightly and move it logitudinally on its metal connector). Is that normal? And with the attached photo shot from the driver's side headlight towards the passenger side door, Which of the two connectors is under full pressure sending fuel to the engine, and what function does the other serve?

Thanks, guys, and Happy New Year.

post-93021-0-04553000-1388238185_thumb.j

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Not sure if you've answered your question already but the line thats on the left side in the picture is your vapor line for the tank vent system. The line to the right is the fuel supply to the engine so that line is more likely to be your culprit. That being said I've never seen one of those connections leak in 10 years of wrenching on these cars but I guess its not impossible someone could have damaged it during removal to replace a fuel pump or level sending unit in the past. You may find that the fuel leak could be coming from the white tank flange itself. Its a very common problem on the cayennes. They crack and fuel being pumped out to the engine leaks out. I would clean that area up as best as you can and then jump the fuel pump relay and watch for a leak.

Edited by PTEC
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  • 2 months later...

Anyone know if there's available some sort of "coupling" which can slice/connect two sections of this fuel hard line? I have access to a fitting that's similar to the one on my pressure line, but that fuel line is not the correct part number as my pressure fuel line. If possible, I'd like to consider grafting or splicing a replacement fitting onto the end of my line. But it can't be some sort of shade-tree deal, and with fuel under that sort of pressure, you can't risk a connection that fails.

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There are several professional kits on the market. However you are going to pay $175.00 to$250.00. They dont just sell the tubing by the foot and the connectors / adapters separately. For the cash you would lay out for the kit it would be better off just to buy the part from Sunset Porsche

Edited by binger
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I have a similar situation. I discovered it due to a fuel smell that is strongest near the passenger side wheel well. I found some write ups about cracked fuel senders and a solution seemed to be to replace the entire unit. I do not feel comfortable addressing fuel-related issues so my local independent is going to try to replace a seal to see if that fixes it.

kwb7.jpg

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Mine has been diagnosed as a cracked fuel line.

Any tips on the replacement procedure? Does the fuel tank need to be removed or is access available solely by removing the under trays?

Overnight it's gone from a suspect fuel sending unit to a cracked fuel line. Can you get an "absolute" confirmation on that diagnosis? Unfortunately, too often mechanics make a "best guess" at the cause of a problem, change the suspected part, and if that doesdn't fix the problem, then move on to the #2 suspected problem part.

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To be clear, I'm the one who diagnosed it as a cracked fuel sender based on seeing fuel on top of the fuel sender and having read about cracked fuel senders on the Internet.

I spoke to the owner of my shop yesterday, having send him the photo that I posted. He initially thought that it might be something as simple as a seal. However, the mechanic looked at it for the first time today. He cleaned the top of the unit and then attached a remote battery to observe the behavior when fuel started to flow. He saw fuel leaking from the line that has the green clasp on it (left side of the picture above.) As was previously pointed out, the fuel flows at high pressure through that line, so the remedy would appear to replace the line.

The part should be here in the next couple of days and is less than $100. Labor will be the highest cost and since this job is outside my comfort zone I do not plan to attempt it myself.

Edited by GromitInWA
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I'd sure be interested in knowing more (as an insight into solving my issue). As I mentioned in my initial post, when I removed the cover there was fuel that had puddled on the top of the sending unit, but I've not yet observed this area with the pump running.

For GromitInWA, I'd be curious if your mechanic could actually see the fuel leaking from the "line" itself (which I would expect to see some sort of spray - given the sort of pressure it's under), from where that line connects to the 90° fitting (the one your reference with the green clasp), or from around/under that 90° fitting. My guess would be that if it's the latter, it will be difficult to determine if the fitting itself is the cause, the physical connection between the fitting and the part of the sending unit it attaches to, or that the part of the sending unit the fitting attaches to has cracked (in which case the sending unit would need to be replaced).

It migh be worthwhile (surely for my benefit, as well as possibly others following this thread) if you can elicit from your mechanic more specific information regarding the question I posed (above) and post his feedback.

Thanks.

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Coloradocurt - yes I'll try to get an answer. I was there and could see him under the hood but I was on a work call so couldn't get close to watch what he was actually doing. Prior to the test, the discussion was exactly about the options you mentioned. I did see him use a spray bottle (soapy water?) and once he was done he'd eliminated the fuel sender itself as the source. I was actually hoping that it was the sender because even though it is a more expensive part, at least the replacement process is well known. My shop has never replaced this particular fuel line on a 996 and nor had the local dealer, so we're in exploratory surgery mode... If anyone has experience doing so and in particular has knowledge of what needs to be pulled apart, please share!

One point worth bearing in mind: while the fuel is under pressure, presumably the leak itself is very small because there is only a small amount of fuel present on top of the sender and I do not notice loss of fuel so I think that rules out a larger quantity of it pooling that gets lost due to evaporation.

Anyway Curt, I'll stop pontificating and ask the question :)

Edited by GromitInWA
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Here you go Coloradocurt:

"We could see that the fuel was leaking from the coupler joint, not the line itself. We did this by drying everything off, then hooking the battery up with jumper cables so we could watch the area. Fuel immediately started leaking from the joint. We inspected the pipe coming out of the sender, and found no cracks, scratches, or abrasions, so concluded that the coupler was at fault. I did order a new sender unit just in case. Will let you know how it goes. We will make an attempt at installing the line without removing the tank, but we won’t be able to evaluate that until we have the line in our hand."

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Here you go Coloradocurt:

"We could see that the fuel was leaking from the coupler joint, not the line itself. We did this by drying everything off, then hooking the battery up with jumper cables so we could watch the area. Fuel immediately started leaking from the joint. We inspected the pipe coming out of the sender, and found no cracks, scratches, or abrasions, so concluded that the coupler was at fault. I did order a new sender unit just in case. Will let you know how it goes. We will make an attempt at installing the line without removing the tank, but we won’t be able to evaluate that until we have the line in our hand."

Thanks. On mine (a recently acquired 2003 C4S), after driving I could smell gas after parking and getting out of the car, but there were no obvious signs (wetness underneath or drips on the floor/ground). Getting the car up in the air and removing the panels underneath, I could see where there was a slight "washing" from fuel that had run down the back side of the tank. That led me to investigate at the top where I discovered what I pictured in my initial post.

Like you, I would suspect the "pipe" coming up out of the sending unit as the culprit, as it's a plastic and vulnerable to possibly cracking. I don't relish the prospect of installing a new fuel line, as the possibility of having to lower the tank may only be the tip of the iceberg in terms of the challenges we'd face all the way back to the engine compartment. Since my car is up in the air with the underside panels removed, I'll take a look today to see if that pressure fuel line appears to be able to be snaked out of there without dropping the tank. Or maybe just lowering the tank an inch or so would work and avoid all the other things involved in completely removing the tank.

Anyone else have experience replacing this fuel line and care to chime in?

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I'll definitely let you know what my mechanic says when they receive the line. From what I've seen, neither the workshop manuals nor Bentley are helpful with respect to the actual fuel line path.

My clue was a slight fuel smell from the exterior of the car, which I determined was strongest from the passenger side wheel well. Googling that turned up "cracked fuel sender"

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Well, I just crawled under mine and it sure looks like trying to change that pressure fuel line with the fuel tank in place is questionable. While my car is a C4 and I believe that those fuel tanks are shaped differently that the C2's, and those two lines are somewhat/slightly flexible, it would be a challenge.

But what appears as a sign of good news on mine is that I've spotted what appears for all the world to be a very small crack in the top of the sending unit housing right at the base of the "pipe" which the fuel lone attaches to.

For PTEC: Does this look familiar to what you've found of Cayennes?

post-93021-0-62241200-1394120180_thumb.j

Edited by Coloradocurt
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Definitely looks like a crack! If that ends up being the cause of your leak, I'm very happy for you!

I took a look at the workshop manual for pulling the fuel tank. It is rather involved and requires disconnecting steering gear and front suspension (I think). Love that since I just got it aligned...

I'm not sure if you feel like attaching a remote battery and trying to do a diagnosis with soapy water to see whether the leak is from the crack on the sender or the fuel line, or whether it just makes sense to spend $300 on a new sender and see what happens... Keep a fire extinguisher handy.

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I'm a big fan of (when appropriate) buying used Porsche parts from reputable Porsche dismantlers. I believe a sending unit is such a case and I'm going to proceed to swap in the replacement. I don't know that any testing of my current setup would prove anything that doing the swap wouldn't, and I'm not too excited about the risk of a fire with live 12 volts and exposed fuel in close proximity.
While your C2 tank is going to be somewhat different than my C4 tank, changing that fuel line with the tank in place would be a serious challenge. If I have to resort to that and try to do it without dropping the tank, my thinking after having inspected from the underside would be (after having disconnected at the tank) to first disconnect that line from any connections/brackets working from back to front, starting at the engine. Then with the entire line free of any connection to the chassis, to use a primary person working from underneath and a helper up top trying to gently facilitate getting the connection end of the line past the initial obstacles around the top of the tank. While you could easily just cut the line and pull it out, doing what I'm suggesting ought to confirm (if you're able to get it out) whether you ought to be able to reverse the process installing a replacement line.

Edited by Coloradocurt
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Update: my shop spoke to the local dealer and was told that there is "a trick" that means that they can replace it without removing the tank. They have not yet received the replacement line, but when it comes in they think that it will take about a day to do the work. If I can, I will try to find out what the trick is.

I spoke to a Porsche dealer and asked them what they would charge as well as the number of hours to replace the line. I had not heard about the "no need to remove the fuel tank trick" and I explained that it would require removing the steering rack and basically disassembling the entire front end. I was quoted 8.5 hours for $1350, which would include the alignment cost.

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Turned out to be the line. Several hours of work and two people were required to avoid the necessity for removing the fuel tank. The trick is to lower the tank. There are two support bars for it and they can be removed. Once the tank is lowered, the fuel line can be snaked through. I'm making it sound easier than it was though... However, at least the entire front end did not have to be dismantled!

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  • 2 months later...

My 2003 996 Targa is currently in the shop with the same issue! I have about 125,000 miles on it and it drives perfectly. About 4 months ago I had to replace the fuel pump....and now the leak???? In any case I have to wait one week for the line to be shipped in from Germany!!!

Thanks for all the great insight.

Edited by Art Ealba
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Art - definitely the line and not the sender? The sender is easier and cheaper to replace. Make sure that your shop knows that they can do the line replacement without taking the front end apart. If they need advice they could probably call my shop that did the work: Chris' German Auto in Bellevue WA.

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