Waterlogged 99 Boxster
 

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?

Call the station
 

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.

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?

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.

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.

waterlogged
 

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.

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.

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.

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?

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.

As always use at your own risk:

I would apply 12v to the fuel pump (plug unhooked) to the terminal that is fed by the gn/wt wire and ground the terminal fed by the br wire.

There are 2 relays involved:

fuel pump relay in position 13 on the relay panel in the left foot well.

the MFI/DI relay in position 1 on the relay board on the left side of the firewall in the rear trunk.

the pump is fed by a 25 amp fuse in c4.

VW special tool 3217 is used to remove the fuel pump. Spec is 52 ftlb so it is tight.

The fuel pump relay can be jumped by connecting posts 30 and 87 (3 and 5).

Thanks Paul. I did some more checking, I checked the fuel pump relay and it was good, but when I jumpered it out and turned the car on I can now hear the fuel pump running. I'm charging the battery on the charger now and I'll see if it starts up. The fuel pump runs continuously right now even when the ignition is off so this can't be a permanent fix.

So now the question is where does the control signal for that relay come from?

D Williams said:
"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."

So next place I'm going to check is under the seat. I don't see any water or water marks behind the drivers side, but maybe I go some in around the doors considering the weather that week. I believe that's the alarm control module. The durametrics thing didn't report any errors in any control modules so maybe it's just a bad wire.

http://www.samstagsales.com/images/vw_matra_3217.jpg

http://www.samstagsales.com/vwaudi2.htm#fuel

Haha, that's a $300 factory tool! Only Porsche...

Luckily I shouldn't have to get into the tank now as long as I don't burn up the pump with my current set up. Battery is almost charged then I'm going to start back tracking the control signal for the relay.

Any tips?

The DME through relays 1 and 2 in the rear and relay 13 in the front are all needed for the car to start.

FP relay control is pin 63 on the DME

But will 1 or 2 in the rear turn off the fuel pump? I'm going to start it in a sec here when the battery charger is done, but I assume the ignition system is working and I'm getting a spark because it was running poorly after the problem arose. So I think it was firing but becoming fuel starved.

right above the real one is a $134.50 alternative.

Note that this is a VW tool, oh wait VW owns Porsche....

Have you checked the alarm computer under the seat to see if it got wet?

The fact that they'd make a $300 tool for this instead of just just putting a flanged cover with a few bolts on it is pretty amusing. The 911's has a gasket and 4 screws.

Nope I'm back to square one now. I charged the battery and tried to start it with the fuel pump relay jumped out and it still doesn't run. The fuel pump definitely works and I don't see any water in the gas.

If it was a relay control problem the jumper would have fixed it. So now it's a bad spark issue or back to the fuel filter being clogged. Anyone know where I can check fuel pressure at the engine? Or atleast downstream of the filter? The filter is in a bad location to access with only jacks.

If the alarm computer got wet it will cause this issue, stop and check it.

The underside of the seat is dry and dusty. There are some cobwebs, so I don't think that's the issue.

Just checking: Does your remote work the locks and trunks?

YOu mentioned the fuel filter. Did you remove it and check if gas was flowing through or that you can get air through it? It very well may be blocked.
Chris

Fuel
Air
Spark

Keep looking.

Time to read the codes on the alarm system and DME with a PST-2 or better.

Codes:

I've read the codes on all the modules with he durametrics. The alarm module has a fault 21 (immobiliser w-lead) stored, but no active faults. I have no idea if that immobiliser code is recent or ancient. v6 (beta) of the durametrics reported no active faults, and I told it to reset all faults just in case. I also grounded the positive and negative battery cables to discharge capacitors in the memory. The remote works.

Fuel Filter:

I can't get to the fuel filter. While Pedro's description isn't bad, it is not a safe job to be doing without a lift. I would like to check the fuel line at the engine to see if I'm getting flow through the filter. Does anyone know the quickest way to get to the fuel rails to check fuel pressure downstream of the filter? It can't hurt too much to check that.

However if it was the fuel filter I would think the fuel pump would be on continuously attempting to get fuel to the engine. The fuel pump relay works, but it is not turning the fuel pump on.

Air:

I disconnected the MAF as someone suggested but I didn't get any change in the conditions. Not ot over simplify things, but there really isn't much more to a modern cars air system than the MAF and throttle. If the throttle were bad it should still idle, even if it's rough. When the car first died and I could still get it to start and idle roughly it would respond to the throttle a bit. It's possible that a nearly complete blockage of the intake would cause the problems, assuming that it would result in the DME shutting off the fuel pump.

Spark:

I don't know the condition of the ignition. I'd hope that I'd get a CEL or fault in the DME if there was an issue with the spark to all the cylinders. If it was just 1 or 2 it would still run just poorly and throw error codes.

The entire fuel pump thing and alarm module might be a dead end I think. A guy a Pelican says that the pump is only going to come on when the engine is cranking or running. If thats the case then the filter is back on top of most likely faults. My 911 fuel pump runs when the key is placed in the on position and turns off when the carbs are ready and the rails are pressurized. So I was assuming the fact that the pump was off whenever I checked it was a problem. Now i'm going to have to go back out and recheck the pump. I don't know if I checked the pump when the car was cranking or just with the ignition in the ON position. I'm assuming the latter.

I need to find a place downstream of the filter that I can check the fuel flow. Then, I can check flow and bypass the filter entirely to see if the car will run.

I probably have to put the seats back in now hahah.

Not true on the lift part. Get a set of ramps and you can get easy and safe access to it. This was one of the easy DIY's and won't take long.

You can pull a fuel line on the passenger side of the motor. Its near the back of the motor and either a 16 or 17mm fitting. Also you need to check for fuel volume, I forget what the spec is but can find it for you.

Try that and see what happens.

Chris

Does the car have an inertia switch to cut fuel supply in case of an accident? It might be worth checking to see if it is tripped.

I don't know Landrovered. I considered that and haven't found any mention of one. But it can't be that because they would turn off the fuel pump via the relay, and I've already tried to run the car with the relay jumpered out to no effect.

This might be my problem...

Well the immobilizer error code may be more important than you are currently ranking it in your troubleshooting.

Start sequence (not porsche specific) is pretty simple.

Power, ignition switch, inertia switch, immobilizer, fuel pump fuse, fuel pump relay, fuel pump, MAF reading, fuel temperature sensor, coolant temp sensor, throttle position sensor, crank postion sensor, cam position sensor, energize coil packs, starter motor, start.

I have seen where folks suggest starting without the MAF connected, I for one don't think this is a great idea or that it proves anything other than the fact that the ECU has a "limp home mode" fuel curve and will in fact run without a MAF although it runs badly.

The devil is in the details, I suggest you re-examine every one of your "givens" and reconfirm your current assumptions before proceeding further to other systems.

I think I saw that car in the pic for sale on eBay!

I highlighted what I've verified to work, or doesn't seem to exist.
No one seems to be sure what the immobiliser signal does, but the consensus thinks it diables the fuel pump, ignition, and injectors. I can't help but think the immobiliser code would disable the starter. The immobiliser is part of the alarm module, and the alarm module disables so much of the car. When it's removed you lose interior lights, starter, window control, and of course both remote and local locks. Removing the alarm module disables the starter so why wouldn't that be part of the immobiliser? Since all of those other alarm module functions work and the module is in pristine condition, I find it unlikely that this is the source of the error. In addition, the car ran, very poorly, but continued to run for several minutes after I started losing power. I think if it was something on the alarm module it would have died hard and not even cranked.

This all happened after I filled the tank from almost empty in the rain. It's not water in the gas, and it doesn't appear to be water in the alarm module, so I'm back to it being a fuel delivery problem. I sucked up a frog or something.

I don't know about Porsche but in Land Rover the immobilizer does not disable the starter just the fuel pump as does the inertia switch. That being said I feel for you chasing this gremlin around.

Have you verified with a test light or multimeter that you are getting electricity to the fuel pump?

Have you checked the fuel pressure sensor? It shuts off the fuel pump when sufficient pressure is built up in the fuel rail. If it is faulty then the pump may think that it has pressure and not turn on.

When the vehicle ran poorly before konking out, it could have been using the fuel in the rail until it ran out of pressure to the injectors.

let me know what you find.

yeah, I'm an electronics tech so I have all sorts of toys. The fuel pump runs fine when the relay is closed, but that doesn't fix the problem. I think it was using up the fuel in the rails and what little was getting by the filter before it died. When I get home i'm going to jumper the relay back out and check pressure at the rail. There is supposed to be a 13mm brass cap covering a shraeder valve that is used to test fuel rail pressure. I'm going to jumpered it out and try to cover myself in gas. If I don't get sprayed it's the filter.

Yes, I use those schrader valves all the time, handy little buggers. If it makes you feel any better I have a friend who ran his LR out of gas and burned up his fuel pump, I have been helping him, I had two fuel pumps of different sytles in my truck and wouldn't you know that his is neither of the ones I had. I had to flat strap his truck to his office which is always a joy. He only ran over the tow strap once.

I used the term fuel pressure sensor but actually meant regulator in the last post.

If you have fuel in the rail and still don't get any joy, I had a recent situation where a bosch controlled motor was dying and would not restart, it turned out to be a bad crank position sensor.

Both of those are definite possibilities. The car makes the usual beautiful vroom when I start it up, but instead of settling down to a nice gurgle, it dies. would the crank sensor give me an error code though?

I'm not sure if it's already been mentioned in this thread, but the ignition switches go bad on these cars very frequently. It's a $20 part from VW, and an straight-forward DIY if you have small hands. It's probably worth changing just to rule it out, lots of strange things happen when it starts to fail.

-james