2002 996 ran fine then won't start
03-12-2017, 04:12 PM
#1
Three Wheelin'
Thread Starter
2002 996 ran fine then won't start
This isn't so much a tech question as it is a record of what happened and what I did to fix it so the next guy who has this happen knows what to check.
TL;DR - A bad fuel pump relay and not the Crank Position Sensor caused a no start condition on car that was otherwise running well.
The story:
2002 996 coupe with 231,000 kilometres - it had a new engine installed back in 2005 at 70,000 kilometres though so the engine has 160,000 kilometres on it = 100,000 miles.
I parked the car for the winter back in October. It was serving duty as my daily driver and was running just fine until then. I drive it hard mostly, but not abusively. The only maintenance I did this winter was replace the front strut top mounts, cleaned and repacked the front strut bearings, and replaced a flaky oil pressure sender - nothing electrical or fuel related.
Over the winter I had to start and move it twice. Both times it fired right up on the first try, but both times it was difficult to start when it was time to put it back in the garage. Lots of cranking, occasional sputter, and then finally it fired. Both times I chalked it up to cold weather....but in the back of my mind I knew something was up.
Then a couple of weeks ago I finished the suspension work, screwed on my tags and took it for a spin. It fired right up and ran well. I drove it for about an hour, then parked it for 10 minutes, then started it again no problem and drove it for 20 minutes, then parked it for an hour. No operating issues at all.
When I went for a restart though it started right away, but it didn't really run; and then it died and that was it. I cranked about 25 times hoping for a sputter start until the battery pretty much went flat and then I called for a flatbed.
While I was waiting for the flat deck I googled 996 no start and the crankshaft position sensor (CPS) came up as a first hit. The advice was that if the tachometer moved during cranking then the CPS was probably ok since this is what sends the signal to the tach. I checked and sure enough I saw 100 rpm on my tach while cranking the motor. A clue.
Note that the computer needs a good signal from the CPS to start the fuel pump...the fuel pump does not run when the ignition is turned on like in the old days. I didn't rule out the CPS but started thinking fuel pump or fuel pump relay.
So - ignoring the common sense above I went and bought a CPS from Pelican for $130. I reckoned that if it solved the problem then it would be a cheap and cheerful fix but if it didn't then I could rule the CPS out as the culprit and I would have a new CPS and since these things apparently fail it would be reasonable preventative maintenance.
The CPS was easy to install - I will let you search for details but it is located on the drivers side where the engine meets the transmission, access from under the car only. It's right under the Air Oil Separator. The plug and loom for the sensor are easily reached. A pleasant job. Unfortunately though - it didn't fix my problem. Car cranked strong but not even a sputter.
So then I went to the drivers side footwell and under the dash, above the fuse panel to find a bunch of relays. The fuel pump relay is third row down, third from the left, and is the only one with pink graphics on it. No need to remove any covers or anything - Pelican has an excellent picture here:
http://cdn4.pelicanparts.com/techart...mall/pic02.jpg
I jumpered the 87 and 30 terminals (also can be seen how to in the photo above) and the fuel pump started running smooth and steady without my having to turn on the ignition.
When I did turn on the ignition and crank the car, it fired immediately and idled well. I gave it a couple of good throttle blips and no problem - no hiccups. Fuel pump good, CPS new - must be the relay right?
So now I'm waiting for my local Porsche dealership to open so I can buy a new fuel pump relay. Looks like a $10 part. I'm pretty sure this is my problem. I opened the old relay open and the contacts look arced and the lever arm for those contacts is a bit wobbly - although it doesn't look or smell like its burned up.
I will post when the new relay is installed and confirm this fixed my problem
Hopefully this helps a guy down the road.
TL;DR - A bad fuel pump relay and not the Crank Position Sensor caused a no start condition on car that was otherwise running well.
The story:
2002 996 coupe with 231,000 kilometres - it had a new engine installed back in 2005 at 70,000 kilometres though so the engine has 160,000 kilometres on it = 100,000 miles.
I parked the car for the winter back in October. It was serving duty as my daily driver and was running just fine until then. I drive it hard mostly, but not abusively. The only maintenance I did this winter was replace the front strut top mounts, cleaned and repacked the front strut bearings, and replaced a flaky oil pressure sender - nothing electrical or fuel related.
Over the winter I had to start and move it twice. Both times it fired right up on the first try, but both times it was difficult to start when it was time to put it back in the garage. Lots of cranking, occasional sputter, and then finally it fired. Both times I chalked it up to cold weather....but in the back of my mind I knew something was up.
Then a couple of weeks ago I finished the suspension work, screwed on my tags and took it for a spin. It fired right up and ran well. I drove it for about an hour, then parked it for 10 minutes, then started it again no problem and drove it for 20 minutes, then parked it for an hour. No operating issues at all.
When I went for a restart though it started right away, but it didn't really run; and then it died and that was it. I cranked about 25 times hoping for a sputter start until the battery pretty much went flat and then I called for a flatbed.
While I was waiting for the flat deck I googled 996 no start and the crankshaft position sensor (CPS) came up as a first hit. The advice was that if the tachometer moved during cranking then the CPS was probably ok since this is what sends the signal to the tach. I checked and sure enough I saw 100 rpm on my tach while cranking the motor. A clue.
Note that the computer needs a good signal from the CPS to start the fuel pump...the fuel pump does not run when the ignition is turned on like in the old days. I didn't rule out the CPS but started thinking fuel pump or fuel pump relay.
So - ignoring the common sense above I went and bought a CPS from Pelican for $130. I reckoned that if it solved the problem then it would be a cheap and cheerful fix but if it didn't then I could rule the CPS out as the culprit and I would have a new CPS and since these things apparently fail it would be reasonable preventative maintenance.
The CPS was easy to install - I will let you search for details but it is located on the drivers side where the engine meets the transmission, access from under the car only. It's right under the Air Oil Separator. The plug and loom for the sensor are easily reached. A pleasant job. Unfortunately though - it didn't fix my problem. Car cranked strong but not even a sputter.
So then I went to the drivers side footwell and under the dash, above the fuse panel to find a bunch of relays. The fuel pump relay is third row down, third from the left, and is the only one with pink graphics on it. No need to remove any covers or anything - Pelican has an excellent picture here:
http://cdn4.pelicanparts.com/techart...mall/pic02.jpg
I jumpered the 87 and 30 terminals (also can be seen how to in the photo above) and the fuel pump started running smooth and steady without my having to turn on the ignition.
When I did turn on the ignition and crank the car, it fired immediately and idled well. I gave it a couple of good throttle blips and no problem - no hiccups. Fuel pump good, CPS new - must be the relay right?
So now I'm waiting for my local Porsche dealership to open so I can buy a new fuel pump relay. Looks like a $10 part. I'm pretty sure this is my problem. I opened the old relay open and the contacts look arced and the lever arm for those contacts is a bit wobbly - although it doesn't look or smell like its burned up.
I will post when the new relay is installed and confirm this fixed my problem
Hopefully this helps a guy down the road.
The following users liked this post:
rubenb (01-26-2021)
03-12-2017, 05:56 PM
#5
Drifting
The success of the jumper test described in Post 1 removes any doubt ? Just keep the shop-made jumper wire & the Pelican photo in the car for future(?) use?
03-13-2017, 10:55 PM
#6
Three Wheelin'
Thread Starter
Confirmed.
The Porsche dealer did not have the part but weirdly my local auto parts store did. Pink Porsche markings and everything.
I plugged it in, car started on the first crank.
Looking forward to another 230,000 kilometres of trouble free motoring.
Also noticed a bit of a scorch mark on the inside of the old relay cover indicating the contacts have been arcing for a while now.
Let the Porsche season begin!
The Porsche dealer did not have the part but weirdly my local auto parts store did. Pink Porsche markings and everything.
I plugged it in, car started on the first crank.
Looking forward to another 230,000 kilometres of trouble free motoring.Also noticed a bit of a scorch mark on the inside of the old relay cover indicating the contacts have been arcing for a while now.
Let the Porsche season begin!
03-13-2017, 11:01 PM
#7
Three Wheelin'
Thread Starter
Important to note that I had just changed the CPS - thereby ruling it out completely. Also note that the fuel pump *sounded* good. Had it sounded like it was grinding or straining at all I would have suspected it, but it just hummed away quietly and steadily.
As far as carrying a jumper wire around all the time - probably not a bad idea in general. Probably lots of other useful things you could do with it and it sure doesn't take up any room in the tool kit.
A friend of mine did an adventure ride to Alaska a few years back and I noticed he had a good long jumper wire with aligator clips in his tool bag.
