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Old January 15th, 2012, 08:50 PM   #11
Hawkdriver
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I agree that it really doesn't have the 'bad fuel pump' feeling ... is it possible I could have that level of contamination in my fuel that it could cause this... or is the good money betting on the bad pickup? I currently have a full tank of gas... if it's contamination, could I siphon the top 4 gallons off to get the floating contamination out? Is that possible without doing damage? Just as an experiment? And if that doesn't fix this, then I can rule out that bad gas, and go for bad pickup... Ugh. I'm frustrated. Thanks for the input.
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Old January 15th, 2012, 09:06 PM   #12
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If it were contamination I would think it would be happening at any fuel level since the contaminants would be mixed up at any fuel level....doesnt sound ,Ike bad gas either...if you had that much contamination your fuel filter would be completely clogged along with a few injectors I would think.
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Old January 16th, 2012, 06:21 AM   #13
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OK - how many gallons do you put in when you fill it up? You really could have two separate problems.

1) I'm betting you've got a bad fuel gauge or sending unit and when you think you're at 1/4 tank you are actually running on empty. This would also explain why adding one gallon solves the problem.

2) Unable to fill the tank all the way. This has been a problem for others previously and it may not allow you to top off the tank. This would answer why you can only add 11 or 12 gallons to fill up.

Having two problems is an easier explanation (think Occam's Razor) than trying to figure out how your pickup got bent. See the attached PET capture.
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Boxster Fuel Tank.jpg  
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Old January 16th, 2012, 07:33 AM   #14
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My SWAG would be your sending unit is faulty and the reason your getting so many diverse answers is its difficult to diagnose problems from an arm chair, so my advice is take it to a good mechanic. Since you're in Napa you might try Baldwins in Novato they're good and thorough.
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Old January 16th, 2012, 08:31 PM   #15
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Quote:
Originally Posted by Tom M View Post
OK - how many gallons do you put in when you fill it up? You really could have two separate problems.

1) I'm betting you've got a bad fuel gauge or sending unit and when you think you're at 1/4 tank you are actually running on empty. This would also explain why adding one gallon solves the problem.
Yup, that's my theory as well
That's why I asked about 3/4 full vs 1/4 empty
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Old January 16th, 2012, 08:37 PM   #16
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I have the same problem

I have the SAME EXACT problem you have, 1/4 gas left in tank and it runs like it is "out of gas". My fix is that I don't run the tank below 1/4 I think it has something to do with the pick up of the fuel/bad fuel reading too, but I am not going to spend any money to solve the problem, just re-fuel more often - besides gives me a reason to have women come up to me at he gas station and ask me about my cool car!
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Old January 17th, 2012, 07:14 AM   #17
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There is an issue with some Boxster fuel gauges that has been discussed here and on other forums. My fuel gauge never read full even after topping off, which is not recommended, but my tank takes another two gallons of gas after clicking off. I replaced the sending/float unit and had the PS2 calibration done, which involves more than just hooking the computer up. The tank has to be drained and a set number of gallons of gas have to be put back in the tank then the computer calibrates. The whole process set me back around $700 and my gauge still goes not read full so go figure. I would think that calibrated or not your red low fuel warning light would come on, mine did before and after the calibration process.
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Old January 17th, 2012, 09:05 AM   #18
BoxsterBob - San Carlos
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As I read through these posts, my first impression was also a faulty gauge reporting 1/4 tank when you're actually empty, however, the one time I ran out of gas in the Boxster (momentary stupidity on my part), it scared the crap out of me. The engine started to studder horribly, then the CEL light started FLASHING. I thought I was experiencing the dreaded IMS failure. I pulled over and realized I was out of gas. I was able to walk home, grab the can and add enough gas to get me to the station. When your car quits, do you get any CEL on the dash?

I can't imagine running out of gas without the computer logging some nasty code(s).
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Old January 17th, 2012, 09:47 AM   #19
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Ok, here's the end of the story... Took the car to a local guy I know to have the fuel drained... either way, it needed to be done. It was either contaminant in the fuel, or some component associated with the fuel delivery system. He tapped into the fuel line, put a jumper in the fuel pump relay, and started pumping all of the fuel out of the fuel cell. It drained until it got to 1/4 tank remaining (where I had the problem), and would drain no more fuel at all. Curious. We popped out the battery, opened up the fuel cell, and took a look inside. Looked good. Nothing unusual. Fuel looked clean. Pump was still secured to the floor of the fuel cell where it was supposed to be... So, we pulled the pump out. Here's where it got interesting. The fuel reservoir, which should have been empty as the fuel stopped pumping at 1/4th tank remaining, was completely full of fuel. We popped open the reservoir, and pulled out the pump mechanism.... and looking down into the gas, there was some black plastic debris. We shined a flashlight into the opening at the bottom of the pump, and it was clear to see that the entire bottom row of impeller blades on the pump had broken off.... So the pump could only draw fuel down to the 1/4th remaining point, and would then be unable to drain the reservoir... I popped in a new fuel pump, and not adding a single drop of extra gas, it fired right up, and ran perfectly. So there you have it. I called every Porsche dealership service department in N. Cali., and was given the "hmmm, I've never heard of anything like that... I have no idea what the problem is...." I guess this isn't the typical symptoms for a failing fuel pump... so I thought I would share so that if this happens to anyone else, you'll know exactly what the problem is. Thanks for all the feedback everyone provided! Take care.

Scott
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Old January 17th, 2012, 09:55 AM   #20
Hawkdriver
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I just went back and reread everyone's posts. Quick afterthought.

Blubox 03: You probably have the same problem I had. If it would be helpful, I can take digital photos and post so you can all examine the damage to the impellers in the bottom of the fuel pump.

Boxsterbob: Never once got a CEL out of this. Haha.

offshore: Thanks for the referral... I'll go see these guys next time. I HAVE been having trouble finding someone closer than Alden in San Jose.

Tom M: Thanks for the diagram. It helped when I took this mess apart.

And findally, the winner is....

Docdanracy: It was a pickup issue. Haha. For the reasons noted above.

Thanks everyone!

Scott
Napa, CA
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