intermittent starting

[nicholas.stockley]

Hi all hopefully someone may be able to help, I have been to 3 garages (not Porsche) to try and solve this problem
Last year I took it out of storage and it started ok, following week it just kept turning over and not firing up, charged battery even jumped it, no joy over the week, I called out AA there Mech turned up and stood with me while I explained the problem, then I turned ignition and it fired up , I did say he was magic, following couple weeks all good no problem, covered about 1500 miles then the same thing happened again
went into garage, they put a larger battery on to turn it over faster, worked for couple weeks
then into another garage new fuel pump, relay control, pump out kit, electrical fit kit, works ok for couple days then same problem , kept turning over and not firing up then out of the blue it would start and run ok,
wouldn't fire up again, immobiliser disconnected and taken out new Coil pack fitted
in storage for last 6 months and started every week ok
today I picked it up started ok, run it to garage filled it with fuel and washed, drove 2 miles de accelerated at roundabout and it stopped running, turning over but wouldn't fire up, towed back to base, tried again to start, fired up no problem and left it running for 5 mins, turned it off and tried to start, just turning over
any suggestions would be very helpful and please don't say sell it like the wife
thanks
Nick

 

[GeoffB]

Nick
I had similar experience on a 3.2 Speedster I owned years ago. Turned out to be the earth lead that goes from gearbox area to chassis. Where it goes over the rear frame it was green with corrosion, I had previously checked and cleaned ends but not spotted this. On way back from Le Mans refused to hot start battery seemed dead . Needed to bump start a couple of times on way to Chunnel. After arriving in UK started ok. Changed lead and never had another problem with it. Might be worth a check
If yours is a 911 check above pedal box the harness has (if I remember correctly) three round connectors that join harness through bulkhead, you can catch these with your foot and dislodge them so check they are fully home

 

[Alpha10]

Glad to know I am not alone!

My ‘84 coupe has started doing very similar!

Only three times so far, but the engine turns over strongly and just won’t fire. I tried swapping out DME relay last time and nothing BUT literally leave it 5-10 minutes and starts first touch of the key as normal. I have no idea what is going on. I am now always worried it could happen at a difficult situation or not start at all.

Mark

 

[pse_SC]

any suggestions would be very helpful and please don't say sell it like the wife

sell the wife

 

[chas3.2]

Do fuel pressure test first.

 

[Alpha10]

Do fuel pressure test first.

Interesting, it has only happened since I had a new fuel pump fitted. The bit I really don’t understand is the waiting only 5 mins and nothing being touched or changed starts straight away. Almost like it was flooded?

 

[chas3.2]

When were the fly wheel sensors fitted.

 

[911hillclimber]

Changing the above, the box/chassis earth strap and another added too, fixed everything.
sensor change is an awkward job, but just take your time, or take to a Porsche independent garage.