Having mechanical issues - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Duke0594 · 11-20-2018, 06:41 AM

I have a 1997 986 Boxster. Was leaving a parking lot one day when she started to spit and sputter then she died. Tried a couple times to get her started back up but it wouldn't happen. As I was sitting in the parking lot waiting for a tow I noticed that even with the key out of the ignition the fuel pump was running. Had to disconnect the battery to get it to shut off. At the time she died I thought I smelled wiring melting or burning. My mechanic was able to get her started after he replaced an injector but was still running really rough. He says that there is gas coming out the tail pipe. He says it is not burning the gas for some reason. He has given up the fight for her so I'm taking her to a professional porsche shop. I should have done this in the first place. Just curious if anyone else had ever had this problem or heard of it. Thanks.

BYprodriver · 11-20-2018, 07:16 AM

Never heard of that in the 10 years I have been on this forum & others. A lot of fuel pumps have been failing the last couple years, maybe this is a new mode of failure. Might be cheapest to go ahead & replace fuel pump & hopefully that's all it needs.

The Radium King · 11-20-2018, 07:39 AM

don't think fuel pump gets a control signal, just on/off power. so, fuel pump continuing to run would not a pump issue but rather a control issue. i *think* there is a relay that turns pump on/off (in emergency situations ecu will shut pump down to stop fuel from spraying around) and this may be bad.

BFeller · 11-20-2018, 01:58 PM

Quote:

Originally Posted by The Radium King

don't think fuel pump gets a control signal, just on/off power. so, fuel pump continuing to run would not a pump issue but rather a control issue. i *think* there is a relay that turns pump on/off (in emergency situations ecu will shut pump down to stop fuel from spraying around) and this may be bad.

I also seem to recall reading that if the engine isn’t running for 10 seconds the ecu shuts the fuel pump off.

Duke0594 · 11-20-2018, 02:42 PM

Thank you for the replies. I asked my mechanic about the fuel pump being the culprit but he said he was 98% sure that was not the issue. I was thinking more of an electrical issue or something to do with the ecu myself. I know just enough about cars to get myself into trouble. I did however change the starter on the Porsche when I first got her. That was a feat for me considering I am not even close to being a mechanic.

NewArt · 11-20-2018, 04:53 PM

Well, kudos on the starter swap! It’s not the easiest job. No clue for the current problem though.

kk2002s · 11-21-2018, 05:46 AM

There is a fuel pump relay that is meant to shut it down in case of accident. Mine went bad, it would over heat and stop the fuel pump. It would cool down then work until over heating again. Seems that if it could over heat and stop the pump, it could possibly go the other way and melt turning on fuel pump. I diagnosed using jumpers and when I jumped over the relay to ON, the pump would just run, I think even with the key off.