Sending unit would be my WAG. With PST2 you should have access to the OBD2 Mode 1 Pid...

Hi all,

New problem. Gas gage only reads 3/4 full when full. Filled up after DE and gage read 3/4. Figured it was me or the pump. Topped it off at home, still 3/4. Didn't take much. No PST2 codes. Sending unit?
Any ideas?

Ed B

Minus 40 degrees... Is that Fahrenheit or Celsius?

If you have access to a PST II then do a tank calibration.
You'll have to have he tank almost dry, then add a small amount of gas (12 liters, IIRC).
Then with the PST II you can recalibrate for that amount of fuel.
Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

I was trying to avoid that. I don't have enough gas cans. I suppose I can put the gas in my other cars. I have a PST2.

Ed B

fuel level indicator which is a byte (8-bits) of fuel level from 0 to 255. If you can read this it might be of some value to see what the number is with the tank full.

Or you may have to obtain this via a query to the comfort (Komfort) bus if one exists in your car. This bus may be connected to the instrument cluster controller which may have a fuel level value that can be retrieved.

'course, you do not have a before reading to go by so...

As I think someone else touched upon you can drive the car and use say half a tank of gas, then subject the car to some wild turns to see if sloshing the gas around might free up/dislodge a fuel line that might be interfering with the fuel level sensor in the tank.

On the outside chance this might be gummed up you might try a bottle of Techron as per directions the idea this will dissolve (if they exist of course) varnishes or other kinds of deposits that are interfering with the fuel tank level sensor's performance.

Just so it is clear before I thought about replacing the fuel sending unit or even opening up the gas tank I'd try to eliminate other causes first.

Sincerely,

MarcW.

Marc,
I just did two DE days, so that should have sloshed the gas around a bit.
I did some playing with the PST2 the other day. If I remember correctly, on a scale of 0-18 the chart was about 14 gallons. Tank holds 16.9. I'll try the PST2 again.
The car is in storage all winter, almost 6 months. I do put Stabil in the tank. I'll try some Techron before I start taking things apart.

Thanks,

Ed B

If sloshing can undo this it can do it would be may take.

Also, sloshing side to side may not be of much help. Based on some vague memory (or hallucination) of where the tank level sender hardware is you may want to generate some violent front to back of the tank sloshing.

A problem is you may not know you've 'fixed' this, unless after a sloshing session you give the tank level sensor/sender time to react,

Sincerely,

MarcW.

The DE event was for two days and included some heavy braking and acceleration. The problem wasn't evident until an hour later when I got home and filled it again on the second day. I'll plug in the PST2 today and see if I can find anything.

Ed

The PST2 said that the gauge reads 13.8 gallons and the sending unit reads 13.8 gallons. I took out the sending unit and it looks like there is 13.8 gallons in the tank. It's not full. I guess the problem is in the fill system.

Ed B

There didn't appear to be any interference with the fuel lines but I may have fixed it by taking the sender out. I then filled it through the normal filler with no problems. Gauge reads full. There is a 996 service bulletin to add some tie wraps to the fuel hoses. Next time!

Thanks all,

Ed B