benclark1973

Was driving the car all day and was running like always..GREAT! Then I get home, shut it off for about 30 minutes, come back out and now it will not start. Turns over fine, but just wont fire. Read a bunch about the possibility of it being the CPS, so I replaced that, but still no life....any ideas?? HELP!! she's my daily driver!!

targa996

Fuel pump ? I'm not sure how you check fuel rail pressure in these cars - but relay should be easy to swap out / test ...do you hear pump priming in frunk when you turn ignition on before cranking ? How much fuel is in tank ?

benclark1973

I thought the same thing...when I turn the key all the lights come on and everything sounds okay....should the pump make sound I can hear from inside the car?? I did not notice any pump sound in the car....I'll open the hood and try again.

tharbin

benclark - if the engine is nice and hot AND the car turns over fine but just seems like it isn't getting fuel AND it has been sitting an hour or so after being turned off, a likely candidate is the purge valve above the alternator. If so, the car will start fine in the morning (probably).

Check this link, there are a few more but knew where this one was. https://rennlist.com/forums/996-foru...l#post13137027

benclark1973

I left it overnight and still nothing this morning... going to replace the fuel relay and see if that does it...should the fuel pump make any sound when I turn the key on? It's clicks but that's it..when I crank it over it smells like gas from the tailpipe.

tharbin

Guess we're not in the same timezone, it's still tonight here.

Unfortunately outside my knowledge area however I seem to remember that someone said that it makes noise for a very few seconds when you turn the key. If it smells like gas when you crank it, doubt it's the fuel pump or relay.

If it turns over fine but doesn't even sound like it's trying to start, CPS was a good guess. I can't really offer any help. Good luck and I hope someone with more knowledge pokes their head into your thread soon.

Ahsai

The fuel pump should prime for about 1 second when you turn the key to the last position before crank. You can try to jump the fuel pump relay.
If it's not the fuel pump, you will need to check for sparks.

Does the tach needle bounce for about 1/8" when cranking? I know you said you replaced the crank position sensor but wiring can also be an issue.

sammaw

Same thing happen to me(2002 c4 cab), just after a Porsche service. Drove it around for the day, parked for dinner, and wouldn't start 1 hr later. It was the fuel relay. apparently not that uncommon according to the dealership. 15 pounds i think for the fix + the transport back to the service centre. Hopefully an easy repair for you at home.

benclark1973

I am picking up the fuel relay and will try to put it in after work this evening. I'll get back with you all and see if that does it....

Macster

Try a new relay. Be sure the fuse is good, too.

When the fuel pump on my Boxster was suspected of dying the tech connected 12V power directly to the fuel pump leads to eliminate any fuse, relay, or wiring problems. (I had of course checked the fuse at home in the driveway and the tech had loaned me his bypass relay to eliminate the relay as the problem.) The pump didn't even run with power connected directly to it.

mharrison

Check for codes.

ZuffenZeus

I had a similar problem like this and it was a simple fuel filter clogged up from low-grade gasoline. Replaced it and filled with premium and wah lah... it fired up.

Gonzo911

What about the battery. When mine died, they went without any warning...

benclark1973

Battery is new, so don't suspect any issues there..fuel filter is a new suggestion, guess I can try that as well. No codes as of yet...YET....

5CHN3LL

If it turns out to be the fuel pump, there is good news: On a C4, DIY fuel pump replacement is a snap. That little square black plastic dome in the front trunk gives you direct access to the top of the fuel tank.