Fuel Gauge Reading - 986 Forum - The Community for Porsche Boxster & Cayman Owners

j.fro · 11-04-2007, 01:43 PM

Well, most of the job was very straight forward. I pulled the sender unit per the TSB instructions. The fuel lines tied together with the cable ties were off a bit. I cut the ties and freed everything up per the TSB. However, after I had just about everything back together, I needed to disconnect a fuel line from the top of the sender again...and the plastic fitting broke.

Looks like I'll be buying a whole new sending unit. Damn.

Padawan · 11-04-2007, 07:20 PM

Man, that stinks.

Where were you able to access the TSB and instructions? My fuel gauge is getting to the point where it's no longer "quirky" to me, just plain annoying.

j.fro · 11-05-2007, 01:37 AM

try renntech.org
You'll need to contribute $25, but it's worth it.

j.fro · 11-20-2007, 02:28 PM

After my mistake (breaking my original fuel sending unit) and the salvage yard's mistake (shipping the wrong sending unit), I've finally got my car back together. The good news is that the fuel gauge reads perfectly now! The Porsche TSB for 2001 and earlier 986/996 says that the cause of an erroneous fuel gauge reading is the way the two fuel hoses are zip tied together. They advise removing the old ties and retying the hoses so that they are perfectly parallel. I simply removed the ties and made sure that they are out of the way of the float (they weren't before). Unfortunately, I can't tell you that this will do the trick, because I ended up having to replace the entire sending unit. What I can tell you is that I got a used sending unit from DC auto for $75. I figure that I'm still ahead vs taking it to someone else. Here's a bit of wisdom that I gained from this: First, be very careful with the plastic fittings on your sending unit. Age, heat, and gasoline will make them brittle. Second, in 2002, Porsche changed the sending unit. The later ones are waaay different. And finally, be absolutely certain you hear a click when reattaching those quick-disconnect fuel lines, then, give it a tug straight back to make sure it is secure.

Padawan · 11-20-2007, 03:05 PM

Thank you for this insight. I probably won't get to this until after the winter, but could you rate the difficult of the entire job? I tried checking out Renntech, but didn't turn up much helpful information.

porsche986spyder · 11-21-2007, 07:14 AM

Okay, there is an easy way to get the correct fuel reading. I have this same problem with my car. I found this out just by chance. This is for anyone getting slow fuel readings after fill up when you know you have a full tank or have just added more gas but it doesn't show it at first and then shows it slowly rise up after driving it for a while. The easiest way to get a correct reading is to turn your ignition key to the on position, all the way to the right, but without starting the vehicle up. Leave it in this position and then begin filling your gas tank up. While it is filling you can even sit in the drivers seat and watch the fuel needle go up along with the digital reading. Works every time and you will never have to guess if your car has a full tank of gas or not. After you start your car the levels WILL stay at the last reading. This works on partial fill ups as well. It's not a perm. fix, but it sure saves you money instead of having the fuel sensor/sendor unit replaced which is the main cause of this problem. Or paying the dealership to have it re-calibrated, which also seems to fix the problem. I would rather just sit and wait instead of spending a small fortune to get a correct gas reading.

Padawan · 11-21-2007, 12:46 PM

Thanks, but the problem I'm experiencing, and the one that j.fro was discussing is an actual issue with the fuel level reading itself. Regardless of how full my tank is, it will never register more than 5/8 - 3/4 or so. The problem appears to be with the float getting caught or stuck somehow inside the tank, which is what the TSB seems to address.