S1 no hot start

[Le TVR]

As per title once the car is up to temperature it will not restart after switching off. If I dont switch off it will continue running normally.
Manual says AAD not closing, so I fitted another and clamped off the air hose to be sure but no change. Changed ignition coil but no better.
Possibly some kind of heat soak after switch off? Ignition amplifier?

[Fefeu52]

I'm not a S1 specialist, I have a S3C. S1 use a K-jetronic injection system... same technology as mk1 GTI Golf. When a mk1 gti Golf has troubles to start when hot, the first point to look is the fuel pressure accumulator. If it is wrong, when hot the fuel vaporize and "vapor lock" the injection system.

[IamWedgend]

My 2.8 cologne Tasmin uses the same system and I had the same issue.

As the poster above says - it's very likely to be related to the fuel system. Check the accumulator as that's in theory the thing that holds the hot start pressure.

If no joy there, also check spark plugs - they can degrade in the heat if old and not fire.

And finally, check your injectors, if they are leaking and dribbling after the engine has been turned off, they may be stopping the spark plugs firing.

[Le TVR]

I cant imagine its the accumulator as the pump would pressurise the system fairly rapidly?
Its going to be a long weekend....

[WotnoV8]

Might be worth disconnecting the cold start valve once the engine is up to temp and then try starting it again to see if that might be the problem?

[Fefeu52]

Le TVR said:

I cant imagine its the accumulator as the pump would pressurise the system fairly rapidly?
Its going to be a long weekend....

You're wrong. If the accumulator is faulty, the fuel vaporize in the system. When you restart the pump, the fuel vapor stay in the circuit and "lock" the system (the system inject Xcc of vapor instead of Xcc of liquid). If the accumulator is dead, the pump can't do anything. Bosh installed this accumulator to keep pressure in the circuit when hot, to avoid fuel vapor. You can believe me, this is the first device to check on a K-jetronic system when you have hot starting troubles.

[Le TVR]

I called my 'local' K-jet specialist in Grenoble and he said the same, change the accumulator, don't bother looking further.

Oh well its only 200 euro...

[phillpot]

Edited that for you

Le TVR said:

Its going to be an expensive weekend....

[v8s4me]

My understanding was that the accumulator was intended to keep pressure in the line to the injection distributor to aid starting during the first few seconds when the pump was building up pressure. Why not try by-passing the accumulator and see if the problem goes away? You may have a wait a few seconds between turning the ignition on and then turning the key again to engage the starter. Then if you find you can live without the accumulator you save yourself a wedge of cash.
Worth a try?

Some useful notes on the CIS HERE

[Le TVR]

Epilogue:

Not the fuel accumulator, however the fuel pump has a non-return valve on the output and if that fails the accumulator can't work.

Yes it's been an expensive few weeks!

And shes now decided to have a dodgy fuse box....

[Fefeu52]

Glad to read you fixed your problem. Thank you for your feedbak, now I know the hot-start problems on K-jetronic can also come from the non-return valve on the fuel pump output. Of course, the pressure accumulator can't do his fonction if the fuel pump leaks.

Now... You just have to enjoy See you at Morges? (if not cancelled)