Waterlogged 99 Boxster - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ARModen · 12-18-2009, 06:37 PM

Ok, I've been driving the boxster to work this week because the Jeep needed a new plug and I hadn't had a chance to replace it yet. It's been a torrential downpour since last weekend. The cars been running like a top all week regardless. It's been putting the jeep to shame really. I got the low fuel light on the way back from lunch thursday. On the way home, I stopped and filled it up. It was on for maybe 10 miles. I stopped and put almost 14 gallons of premium in it. I made it maybe 50 feet before I started losing power. I pulled back into the station. It idles rough for a few minutes then stopped. I started it again, it idled again for a few minutes, then nothing. Now it turns over but doesn't pick up.

So far I've verified no blown fuses. I don't have a CEL and didn't have any warning lights when it was still running. There haven't been any problems or any recent maintenance. I tried to sample the tank but can't get a siphon line in far enough yet.

I assume it's bad gas and either I have enough water to prevent it from running, or I've sucked something in and clogged the filter. It's also so full that I can't get a significant amount of alcohol in to dry the gas out. My plan tomorrow is to get it up in the air, change the filter, and in the process drain the lines and the bottom part of the tank. I figure it's not an electrical issue because there were plenty of oppurtunities for that to occur earlier in the week. Does anyone have any other suggestions?

mikefocke · 12-19-2009, 06:19 AM

you got it filled at and ask in a non-confrontational manner if they have had any reports from others. See if you can pin-point the cause before you start trouble shooting.

Also plan on where you'll dump 14+ gallons that could blow up a sewer if dumped there.

ARModen · 12-19-2009, 11:50 AM

I asked and they hadn't received any complaints, but the woman behind the counter was pretty clueless as to whether or not anyone have gotten premium gas in the last few hours.

I hooked up the durametrics and it said there was a p0102 (porsche code 115) error. Anyone know if this sounds like a root cause, or just a symptom of me trying to get it to start?

sd_boxster · 12-19-2009, 04:18 PM

Someone smarter than I can chime in - but Google says those are MAF codes. My understanding is that you can disconnect the MAF and try starting it to see if the situation improves - if so, maybe just a bad MAF.

Paul · 12-20-2009, 03:32 PM

Remove the battery.

Remove the tray under the battery.

Remove the hose on the fuel pump outlet.

Attach a spare hose to the outlet and siphon out enough gas to check for water.

ARModen · 01-23-2010, 01:41 PM

Just geting back to weorking on this. I disconnected the MAF and had no change in operation. Engine still rolls, but doesn't catch/no combustion.

ARModen · 01-23-2010, 02:33 PM

Ok, so further investigation leads me to believe the fuel pump is bad or plugged up. I disconnected the line on top of the tank and attached my siphon line. I then hooked up the battery and turned the car on expecting to use the fuel pump to pump down the tank. Nothing came out. I tried with my siphon hose attached to each line and same result, no flow. Not particularly the safest operation, but if it was bad gas, using the fuel pump to pump the tank down would be the fastest fix.

I checked the fuel pump fuse (C4) fuse wasn't blown and that there is 12V there. There doesn't seem to be 12v across the plug on top of the tank though.

So either it is the fuel pump and I'm not reading the plug right, or maybe theres some relay in the circuit to control the fuel pump that I'm missing. My ancient 911 fuel pump pumps till the fuel rails are full then stops by itself.

So if there is anyone thats familiar with the fuel system I have a few questions:
1. What would prevent gas from pumping out of one of the three pips on top of the fuel tank?
2. Is there a relay somewhere between the fuse box and the pump?
3. What should I be seeing across the pins of the plug on top of the fuel tank.
4. Mostly importantly, how on earth do you get that ring off there to get the pump and level sender out?

ARModen · 01-24-2010, 11:21 AM

Apparently there is a relay. Now I need to find it, and see if it's bad or if it's indeed the computer or alarm system thats disabled the pump.

D Williams · 12-21-2009, 07:21 AM

Just for fun.. if it's been raining that much, check under the drivers seat and see if it's wet?? lost my control mod due to water. It controls a ton of stuff. If it's wet water will enter the box from the back side lower plug and ground things out. It can be causing the alarm to kill the spark. Engine will still turn over but will not crank.

Soetekouw · 12-30-2009, 01:39 PM

It is probably bad gas. I had the same problem about 2 months ago.

Car has been running fine. On the way to work I stopped at the gas station (Shell - always go there) and filled it up with premium. Aproximately 2 miles down the road my car started backfiring, shaking, and wanted to quit running. Made it to my dealership where they put it on their tester. All cylinders were misfiring and errors all over the place. They kept the car for several days and compared with readings of another Boxster. Finally put in a can of Octane Booster and observed it for awhile longer.

Bottom line - bad gas. Cost me $400.