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

Strawfordt · 08-04-2006, 02:54 PM

Everyone's been very helpful here....Thank you.

Has any one had a problem with their fuel gauge? After filling I'm getting a tank reading of about 3/4 full. Maybe i"m getting an early shut off and leaving the tank empty.

Please share your experiences.

All the best

Strawfordt · 08-10-2006, 12:23 PM

No one has had a fuel tank reading concern???? Bummer.

70Sixter · 08-10-2006, 12:29 PM

This is all I found in one search:

3/4 is as full as it gets!

Strawfordt · 08-10-2006, 01:07 PM

Quote:

Originally Posted by 70Sixter

This is all I found in one search:

3/4 is as full as it gets!

Thanks Mike.

Not worth the hassle. I guess i'll be leaving it then.

Sammy · 08-10-2006, 01:10 PM

I can't say that I have had fuel reading concerns but what I can say is that I had trouble with my fuel gauge. The fuel gauge would take 10 miles after I left a gas station to finally read full. The needle moved that slow! The dealer replaced the sending unit and that did not fix it. They finally replaced the gauge cluster and all is well now. Can't help with your concern but can confirm issues with the gauge.

derb · 08-10-2006, 02:44 PM

Strawfordt,
Once again I have the same problem going on. My fuel gauge will read just under 2/4 after a fill-up. It will go to 4/4 once in a while. Once the fuel level drops past the stuck position of the gauge needle the needle follows the tank level. Right now I just fill-up after about 250 miles and it only takes about 10 gallons.
Once or twice I have been able to get the guage to read correctly by just turning the key on and off several times.
It's annoying as RandallNeighbour has posted. I also have never had a fuel gauge problem with any vehicle I've ever owned.
I'll get it fixed eventually but it's not at the top of the 'things to fix' list for my '99. The list is quite long so I put this near the bottom.
Sorry I have no solution but I feel your pain- along with Randall's pain.

Regards,

derb

Strawfordt · 08-17-2006, 09:35 PM

Derb

Quote:

Originally Posted by derb

I'll get it fixed eventually but it's not at the top of the 'things to fix' list for my '99. The list is quite long so I put this near the bottom.

What else is on your list. I'm finding new opportunities (read problems) all the time.

My nightmare is the RMS leak. Downright infuriating. Dealer says he can replace the RMS but he cannot guarantee that it will not leak again. Even with the Cayenne RMS. Dealer said that if you're not a daily driver then the seals dry out a little and then tend to leak. At the same time the dealer said "he wouldn't be too concerned until the vehicle strated spraying out oil"

Scary advice, don't you think?

Padawan · 10-21-2007, 03:15 PM

I have this exact same problem, where the gauge will only show 3/4 full when I've "filled" the tank. I can't tell whether the tank is actually completely filling, or whether the gas pump is somehow tripping too early and not giving a complete fill. It's a bit annoying, and I'm curious if this is a common issue, and/or if there's a simple fix?

Cloudsurfer · 10-23-2007, 06:59 AM

I have the opposite problem, which only occurred since I swapped clusters for a 996 cluster. Mine consistently reads optimistic, which I have concluded I need to go through the calibration process and that should cure my situation.

In yours, I would first pull out the sender, look at it, clean it, test the voltage it puts out, and see if that doesn't help. If the sender appears to be working properly, you may need a recalibration.

Patrick

Strawfordt · 10-29-2007, 06:58 PM

Quote:

Originally Posted by bmwm750

I have the opposite problem, which only occurred since I swapped clusters for a 996 cluster. Mine consistently reads optimistic, which I have concluded I need to go through the calibration process and that should cure my situation.

In yours, I would first pull out the sender, look at it, clean it, test the voltage it puts out, and see if that doesn't help. If the sender appears to be working properly, you may need a recalibration.

Patrick

Okay, that is interesting. How does one perform a recalibration of the fuel gauge?

I might just go for this one.

Tom

Cloudsurfer · 10-30-2007, 02:37 AM

Ask your dealer, its a very specific process that involves draining the tank, adding a specified level of fuel, and calibrating with the PST.

Patrick

j.fro · 10-30-2007, 04:31 PM

I've got the same problem on my 2000 S. The fuel gauge reads 3/4 after a fill up, sometimes goes up after a while, sometimes not. It seems to be accurate from 1/2 on down. Porsche has issued a Technical Service bulletin for this. It involves untangling some of the wires, hoses, and fuel gauge float in the fuel tank. It doesn't look to be too much trouble. I'll have a go at it Saturday and let you all know how it goes.

Padawan · 10-30-2007, 06:41 PM

Quote:

Originally Posted by j.fro

I'll have a go at it Saturday and let you all know how it goes.

Please do!

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.