996tt wont start

[Nobbles]

Aaaargh. So last Friday - daddy cool picking up the kids from the nursery. All loaded in but it wouldn't start. The starter turned but would not catch. Kids unloaded - although reluctantly as they really do love travelling in it, so tears and tantrums - followed by a walk home. Not so daddy cool. I went back a couple of hours later and the it was the same, I then tried a technique juqt letting a couple of turns of the starter then stopping on the third attempt it started with this technique. Saturday, off to the shops, car was left for maybe 2 hours no issues. Today after no use I went to start it and the same problem. Starter turns but it doesn't catch, tried the 3 turn technique, this didn't work either. mmmm - any thoughts?

[MadMark911]

Nothing for it but to get it on a low loader to a specialist as it'll need to have it's diagnostics checked. It could be so many things ..... a sensor that has packed up etc. I've even heard of old immobilisers playing up and doing this!

[Moosh]

Flat battery

[Rockster]

Nobbles said:

Aaaargh. So last Friday - daddy cool picking up the kids from the nursery. All loaded in but it wouldn't start. The starter turned but would not catch. Kids unloaded - although reluctantly as they really do love travelling in it, so tears and tantrums - followed by a walk home. Not so daddy cool. I went back a couple of hours later and the it was the same, I then tried a technique juqt letting a couple of turns of the starter then stopping on the third attempt it started with this technique. Saturday, off to the shops, car was left for maybe 2 hours no issues. Today after no use I went to start it and the same problem. Starter turns but it doesn't catch, tried the 3 turn technique, this didn't work either. mmmm - any thoughts?

Not clear what you mean. If the engine cranked but would not fire that can be the fuel pump or another cause is a critical sensor is not working (like crankshaft position sensor) and while the engine will crank it will not run, not even attempt to run because the DME without that sensor info can't know where the pistons are and thus will not trigger fuel injectors nor spark. Because emissions are not affected no CEL (check engine light) is turned on.

If the engine failed to crank and there was not a sound from the starter this can be the immobilizer (the RFID pill inside the key didn't send its security ID over the in-dash transceiver is one possible cause) or a bad/flat battery.

Or it can be -- if the car is a manual -- a bad (intermittently bad...) clutch safety switch.

In the case of a Tip it can be a bad (intermittently bad...) Park switch. The engine will not crank if the transmission shifter is not in park (and maybe the brake depressed as well... I'm Tip inexperienced).

AFIAK, the starter motor should not spin without being engaged with the flywheel ring gear teeth. The general operation is the starter solenoid is energized and moves the pinion gear into engagement with the flywheel ring gear. Only then is another switched closed that energizes the starter motor windings and spins the starter.

Another possible explanation is the ignition switch is bad.

Sincerely,

Rockster.

[Nobbles]

So the engine turns over but does not start. Battery is good. Checked the fuel pump fuse, OK. Opened the fuel cap - old wife's tale. No difference. Looks like the flatbed to the specialist.....
Just hoped it would start once to get it to the garage, not to have the hassle of the flatbed.. Ho hum.

[Moosh]

Nobbles said:

So the engine turns over but does not start. Battery is good. Checked the fuel pump fuse, OK. Opened the fuel cap - old wife's tale. No difference. Looks like the flatbed to the specialist.....
Just hoped it would start once to get it to the garage, not to have the hassle of the flatbed.. Ho hum.

Have you tested the battery?

[Nobbles]

I have not tested it, but the starter motor turns over at the normal speed and it is normally connected to the battery conditioner when not in use for a couple of days. I reconnected the conditioner this morning. I will have a final try this evening before calling the flatbed for the morning.

[Lancerlot]

The high pressure fuel pump is the likely culprit!

[Rockster]

Nobbles said:

So the engine turns over but does not start. Battery is good. Checked the fuel pump fuse, OK. Opened the fuel cap - old wife's tale. No difference. Looks like the flatbed to the specialist.....
Just hoped it would start once to get it to the garage, not to have the hassle of the flatbed.. Ho hum.

FWIW, the only times I have had a Porsche (my Boxster) not start with the engine cranking normally was when the fuel pump quit and another time (more than once) when what proved to be a bad (intermittently so) clutch interlock switch.

In the case of the fuel pump a tech loaned me a fuel relay bypass plug which I used to confirm the fuel relay was not bad. The fuel pump had just up and died, after over 200K miles.

In the case of the clutch interlock switch, the last time the car would not start after nearly 15 minutes of trying when every time before it would start on the 2nd or very rarely a 3rd try was needed.

It was so bad that I had nearly given up and was considering my options when I gave it one last try. Bingo! The engine fired up and I had the tranny in gear and the car miles down the down the road in no time.

Next day the car was in the shop to get that sorted out.

Side note: A new clutch switch made the symptom go away but the symptom has returned once or twice in the nearly 2 years since I had the switch replaced. The new switch is intermittently bad but so far I have not bothered to replace the clutch interlock switch a 3rd time.

Unless you find the fuel relay is bad or if the car is equipped with a manual tranny fully releasing then fully depressing the clutch pedal a few times or if the car is equipped with a Tip shifting out of park then back again and trying the starter, the car's going to have be looked at by a pro.

The Turbo can suffer a fuel tank fuel pick up problem in that one of the fuel siphon jets suffers a cracked or broken hose and the engine runs fine until the fuel level drops below one half tank then because the fuel jets (these siphon fuel from either basin and supply fuel to the pump) do not work the car runs out of gas with 1/2 tank of fuel in the tank that the fuel pump can't pump.

Then there are of course other possible causes: bad sensor of some kind, even perhaps a bad ignition switch.

Sincerely,

Rockster.

[Nobbles]

I waved it bye bye on the flatbed this morning. I'll keep you informed.

[Nobbles]

Did not start in the garage, no faults on the diagnostic. Fuel pump not working. This morning it started? The thoughts are a faulty fuel pump/ dirty fuel filter. It had a major service last november so I presume the fuel filter was changed. Anyway it will stay in the garage for a few more days to see if the same problem occurs to be sure it is the fuel pump before changing it at 500 euros + tax.

[davek_964]

Nobbles said:

Did not start in the garage, no faults on the diagnostic. Fuel pump not working. This morning it started? The thoughts are a faulty fuel pump/ dirty fuel filter. It had a major service last november so I presume the fuel filter was changed. Anyway it will stay in the garage for a few more days to see if the same problem occurs to be sure it is the fuel pump before changing it at 500 euros + tax.

If it is your fuel pump, something to keep in mind :

A year or so back, I had problems with my fuel pump - loud whining noise. Blocked fuel filter was assumed to be the cause, causing extra load on the pump - even though I'd also had a major service not so long before.

Fuel pump + filter were replaced, problem solved - for about a month. Loud whining came back.

Turned out, the level sensor in the turbo also has filters and they were the problem, so I had to get that replaced (can't remember the cost). Fuel pump was replaced under warranty, as I'd clearly been given a defective one (although obviously I still had to pay the cost of the first one).

Probably not relevant, and if it is your fuel pump it's probably just because it's old. But be aware that if it's died because it's been overworked, it might not just be because of the "normal" fuel filter.

[steve singh]

Nobbles said:

Did not start in the garage, no faults on the diagnostic. Fuel pump not working. This morning it started? The thoughts are a faulty fuel pump/ dirty fuel filter. It had a major service last november so I presume the fuel filter was changed. Anyway it will stay in the garage for a few more days to see if the same problem occurs to be sure it is the fuel pump before changing it at 500 euros + tax.

In a way it's good news it didn't start - the last thing you need is to keep chasing the problem down.

Hope you get it back on the road soon and thanks for updating.

[madala]

.....my gut feeling is that it's an electronic problem......an engine sensor of some sort....well....at least that was happened in similar circumstances on my 993 (reference sensor for/to the ECU)......good luck.

[Nobbles]

Now the problem is that it starts??? So until it does it again he cannot check the sensors etc.... Luckily the weather is not so good... but there is a track - evening next Friday that I was interested in going to - my first ever (with my own car)..

[Sunnysidebb]

Have you had the fault codes read, its been said many times on here, but if you own Pork you should get a Durametric. Its well worth the expense, just the cost of a handful of full fuel tanks and you have a brilliant tool that will not only tell you fault cosed but will do test modules, code modules and lots of other thinks. i have both a Durametric and a PST2 and I recon the Durametric is all you will need.
There is a good chance that your DME will have logged a fault when it didn't start. For eg, it could very well be a sensor. eg:You might have had a sticking throttle valve. They go through a sequence when you turn the ignition key , if it got stuck it will cause all sorts of problems.
Without a fault code it will be very difficult to diagnose a problem over the web.
Frank

[Nobbles]

No faults came up.

[Sunnysidebb]

Nobbles said:

No faults came up.

You say no faults , but what did you use to read the faults. Some hand held fault code readers dont show all the available codes.
You wouldn't believe how many there are.
If you had suffered the dreaded fuel pipe split problem you would not have been able to start the car as once it splits that's it.
Ax Rockster said, it does sound like the clutch switch/interlock might have been a bit sticky. If its running fine now and you definitely have no codes as read with a durametric or equivalent then there is not a lot you can do about it untill it does it again.
If it does do it again, make sure you get the codes read before you disconnect the battery as you will clear out any DME fault codes if you do.

[adzy999]

Provided the fuel pump is running, then replace the crankshaft position sensor. Sometimes doesn't log a fault even when faulty.

[_gez_]

It is not the interlock on the clutch as the car is turning over.