Please help me before I lose my mind... Fuel problem!

[scott.staubin]

I am about to lose my mind. Here's the story. I have an 02' Boxster S. I fill the tank, and it gets completely full... of course, only after manipulating the stupid pump handle to get the tank full as it shuts off every 2 to 3 gallons.... but I digress. I drive the car thereafter, and it runs perfect! Until.... just below 3/4 tank... should be approximately 4 gallons remaining. And then the car acts like it has freakin' water in the gas.... it quits, or stumbles, and shuts off for a moment, only to catch again... I though...ahhhh, I got water in my gas. So I put some fuel treatment into the tank that is the anti freeze/remove H2O from you tank stuff... I've used this in the past on various hoopties I've owned in the poorer days.... haha. I ran a couple tanks this way, being sure not to get below 3/4 tank.... and today was the day off to experiment by driving below 3/4 tank between to strategically located gas stations. Oh, I forgot to mention that when this crap happens... just a single gallon of gas, and the car runs like new again.... anyway... today, at just a tad under the 3/4 tank level... the car freakin' died, and absolutely would not restart until I put 2 gallons of gas into the tank... than like new again. I called someone that has worked on my car before... too far to drive at this point to be practical.... and he suggested maybe the fuel filter was clogged or the fuel pump was on the way out. I just finished searching every Boxster forum I could find, and the impending signs of fuel pump failure are nothing like this at all... But putting in a fuel additive does nothing! HELP!!!! I'm going to sit here and drink Sam Adams Cherry Wheat until someone replies! I'm going nutz! Thanks in advance.

Scott

Napa, CA

[scott.staubin]

someone emailed me and pointed out the type o. At 3/4 GONE, 1/4 remaining, this is where the problem develops. Thanks.

[ChrisJP]

AFAIK, on 2002 the fuel filter is located inside the tank and not serviceable.

So you are left with the pump unless someone more knowledgeable comes with additional input.

[ericinboca]

The symptoms closely match an experience I had with a dying fuel pump. I, too, thought at first there was water in my fuel. I could get it to start if I let it cool for an hour or more.

I'd change the pump.

[ppbon]

Have your tank gauge calibrated.

It could be showing 1/4 left when it's really empty.

You'll need a PIWIS or PST-II unit to calibrate it.

Happy Boxstering,

Pedro

[N41EF]

I suspect you have a fuel level sender problem, or as Pedro said it needs to be calibrated. Does your car have the original cluster in it? Since gas (and oil) is lighter than water, and the pump sucks at the bottom you don't have a water problem, you have a fuel problem. Remember that the pump is cooled by fuel going through it so running it low or out of fuel is really bad on it.

How long have you had the car? Is this since you've had it or is it something new?

A plugged fuel filter wouldn't care how much fuel is in the tank.

I'd pull the pump/sender out and check it over, Make sure the sender is the right part number. There have been issues where someone changed a cluster or sender and the gage wouldn't indicate correctly. Some times they can be coded, sometimes not.

Let us know what you find.

[JFP in PA]

Attach a fuel pressure test gauge to the fuel rail and check the pressure before and when the tank gets down to the magic level, if it suddenly falls off, I'd pull the fuel pump and reservoir and check them; they could be either blocked by debris or coming apart............

Edited January 17, 2012 by JFP in PA

[wvicary]

You could have three separate issues.

1- The fuel tank is not venting correctly when filling causing the pump to turn off early.

2- The fuel pump is cooled by the fuel in the tank, the low level could be causing it to overheat and reduce it's RPM which affects pump output.

3- The fuel level sender unit is failing or out of calibration.

2&3 have been referred to and you really need to test the fuel pump for pressure and volume with the low fuel level as mentioned by JFP. You can also measure the current consumed by the pump but that often isn't needed. If the pump is at fault be sure to replace the fuel filter also and be sure the tank is clean of any sediment/swarf/water.