Need help, no start.

[SBK930]

New turbo in.
While the rear was up on my ramps I started the engine and ran it for about 5 minutes and all was fine.
Put back on the ground after reinstalling the rear bar and it just will not start.
I have spark from the coil and at the plugs, the fuel pumps sound to be running, and the engine is turning over fine.

HELP

Steve.

[Rawknees'Turbo]

No crank sensor (except for yer palms! ).

I wonder if you bumped the overboost sensor's wire when you were re-installing your intercooler (worth a lookie, regardless)?

[SBK930]

Originally Posted by Rawknees'Turbo

No crank sensor (except for yer palms! ).

I wonder if you bumped the overboost sensor's wire when you were re-installing your intercooler (worth a lookie, regardless)?

Hi ya Rawknees,

Deleted my last post because it will not start again.
When I did get it to start I turned it off and restarted it a few times with no problem.

Went to take it outside to wash it and again ......no start

What and where is the over boost sensor wire.
It did start while it was on the ramps after IC install.

Thanks Steve.

[Rawknees'Turbo]

Steve, the overboost sensor is on the back side of the secondary intake manifold (also known as the recirculation valve housing, blow off valve, etc.) - it is on the left side, below the intercooler, towards the fuel head. The switch reads boost pressure, and at around 1.2 Bar, opens ground to the fuel pumps. If the wire comes off/partially off (bad contact) = no start, and if the switch goes bad, no start also. You can test it by unplugging the wire from it and grounding the wire end on a nearby, metal component (bypasses the switch and fuel pumps run).

Here it is - I pulled the pic off Google (squiggly yellow line was already there ). The switch is near the curved section of large hose and has a single spade on it.

[SBK930]

Got it, thanks mate.

Since my last post and before reading yours I got it started.
I pedelled the accelerator while cranking and it hesitantly started.
Took it for a drive with the bride following and all appeared ok, bit of smoke when getting on boost........butt that’s to be expected ...(smokin butts(*)

Maybe a fuel issue then as I have never had to peddle it to start it before.
I will have a look again tomorrow as I am cracking a coldy now. Had enough for one day.

Thanks again Raw one.

[SBK930]

Faaaaaaaark, just got back from picking up the worker (son) from night duty and thought I would turn it over and see how well it started and ...............NOTHING

[slow&rusty]

If you spray ether (starter fluid) into the intake will it start?

[SBK930]

Originally Posted by slow&rusty

If you spray ether (starter fluid) into the intake will it start?

Have not tried that slow&rusty.

I have done that before to carburettors, never to my 930.
Do I remove the air filter and spray there or is that not the way to do it.

Steve.

[pkabush]

[QUOTE=SBK930;10348518]Hi ya Rawknees,

Went to take it outside to wash it and again ......no start

There’s your problem
The green wire (comes out of the back of the distributor) can cause intermittent no start issues as well. I’d take Scabby’s advice on grounding the O/B switch first though.
Simply pull the wire off the sensor and attach it to clean unpainted steel. You can extend the wire and ground it to the coil mount on the fan strap. Also a good idea to read through the “no start” sticky at the top of the page. Lots of good info there.
Good luck

[SBK930]

[QUOTE=pkabush;10349016]

Originally Posted by SBK930

Hi ya Rawknees,

Went to take it outside to wash it and again ......no start

There’s your problem
The green wire (comes out of the back of the distributor) can cause intermittent no start issues as well. I’d take Scabby’s advice on grounding the O/B switch first though.
Simply pull the wire off the sensor and attach it to clean unpainted steel. You can extend the wire and ground it to the coil mount on the fan strap. Also a good idea to read through the “no start” sticky at the top of the page. Lots of good info there.
Good luck

Thanks pkabush,

Enjoying a coffee and will go and try the earthing.

Steve,

[SBK930]

Worked a treat guys.

The wire was securely attached.
Does this mean the overboost switch is terminal ?
As the bypass to earth fired the engine.

Big thankyou Rawknees and pkabush.

Steve.

ps: Is it ok to drive like this until a new switch is installed ?

[mark houghton]

Yeah it's ok to drive with the OB lead grounded, though your fix looks kind of Fred Flintstone'ish and not in keeping with the fine marque these cars are :-)

The OB switch is just a safety feature to shut off your pumps should you get over zealous on boost. Factor setting if I recall is something around 1.2 bar to activate the switch...when the switch is new. When activated, it opens and interrupts the ground to the pumps...through the infamous yellow relay which ultimately provides the ground path to the pump circuit. Lots of sometimes stupid German redundancy/things to go wrong (not to say that German's are stupid, but sometimes I wonder about what the Porsche designers were smoking back then).

[Alan L]

That switch is grounded and forms the circuit (while grounded) to trigger the relay for the pump circuit. If you over boost you push the grounding pin (internal) off its seat and breal the circuit that is the energiser for the pump relays. So the pumps stop. Yes you can permanently earth it - no problems will run fine. BUT you have lost your overboost protection. My guess is you will find a wiggly spade terminal on the switch = an intermitent fuel pump issue. Perfect recipe for frustration and roadside strandings. Not to mention having another car up your date on the track.
Basically a new switch. Pull the old one out and hook ohm meter to the spade and the body - should be circuit. Wiggle and play with the spade - my guess is the circuit will be intermittent. Chuck in bin.
I had that issue with intermittent shut downs - very hard to diagnose because next time it fires, or you go to check that circuit and move the wire, and it works.
Regards
Alan
Edit - Mark's and my posts crossed. Sorry. Duplication.

[SBK930]

Thanks Mark and Alan.

Steve.

ps: my flinstone fix was done in a rush this morning as we were out for a drive with the Jeepers today. Beautiful Gorge country.
Will tidy the wiring before driving.


Promise.

[Rawknees'Turbo]

Great to hear, Steve! Now about yer born-with crank sensors!!!

Originally Posted by Alan L

. . .

Edit - Mark's and my ***** crossed. Sorry. Duplication.

???

!!!




So they call that, "duplication" in yer country?!?! Weird!!!

[SBK930]

Originally Posted by Rawknees'Turbo

Great to hear, Steve! Now about yer born-with crank sensors!!!




???

!!!




So they call that, "duplication" in yer country?!?! Weird!!!

Hope to encourage the bride into some cranking later.

Then repeat/duplicate and do it again.

Steve

[SBK930]

Got the 930 out for a run today, with the wifey for lunch at a local vineyard. Nice and warm around 30*c great lunch and cold beer was had.

Went to start it for the trip home and ...........NO START

I can hear the pumps running, still have the bypass from OB to ground.
Was readying the call for a tow truck and before running the battery flat got it started by peddling the accelerator and with hesitation and rough idle it came good.
The idle returned to normal and it ran flawlessly all the way home. Checked the oil level, turned it off, then started straight away.
Very confusing too say the least.

Any other ideas out there why I am experiencing this issue.

ps: got her up to boost numerous times and no smoke .......liking the 7200. :

[Rawknees'Turbo]

Steve, another thing that can cause phantom starting/running problems is a failing CDI box. The next time it does the "no start" routine, see if you can hear the high pitched whine from the CDI when the key is in the on position (but even that is not a 100% guarantee that the box is good and I know of no other way to home test it - would have to find someone in your part of the world that has the equipment and know how for that).

Also, it would be worthwhile to unplug the wiring harness from it and clean all the pins and sockets (as well as the harness ground that attaches to the mounting bracket for the coil).

Sweet about the 7200!

[SBK930]

Originally Posted by Rawknees'Turbo

Steve, another thing that can cause phantom starting/running problems is a failing CDI box. The next time it does the "no start" routine, see if you can hear the high pitched whine from the CDI when the key is in the on position (but even that is not a 100% guarantee that the box is good and I know of no other way to home test it - would have to find someone in your part of the world that has the equipment and know how for that).

Also, it would be worthwhile to unplug the wiring harness from it and clean all the pins and sockets (as well as the harness ground that attaches to the mounting bracket for the coil).

Sweet about the 7200!

Hi mate,

I left it for an hour then went to start it and again ....NO START .

So again I peddled the accelerator and got it to fire up.
It is rough when first fired but quickly returns to idle fine.

It feels and sounds kind of like there is no fuel when turning the key and I can definitely hear the pumps run.
Peddle it and the fuel appears to turn up and I can turn it off and start it straight away without fail.

Steve.

[Alan L]

Then you prob need to check your pressures and make sure WUR is doing right thing.
Could be fuel accumulator (Rest pressure) is failed. I just ordered one for mine today - rest pressure dropping right off when pumps off. You may have two issues.
Regards
Alan