Hot engine won't restart on hot day

[ptopping]

If it is a hot day and I drive the car up to temperature and park up for 10 mins, when I try to start again the starter motor turns but no fuel is getting to the engine. If I leave it for 20 mins it starts OK. I know that no fuel is getting to the engine because it is not flooded. This happens when the outside temperature is above 25 degrees. It also happens if the Auxiliary fan has kicked in after stopping. Help please. I have posted this in electrical also because the garage has checked the error codes and nothing shows. If I keep the engine turning there is a message on the dash that says "FAILSAFE ENGINE MODE" I have had a replacement thermostat fitted about 2 months ago.

[joejag308]

Who ever you are.........i have submitted your queerie to Dave Marks for his interpretation of your problem..........it has happened before im sure
Joe...........manchester eh?........

[ptopping]

Thanks for your fast response Joe

Regards Peter

[joejag308]

Peter the reply from Dave Marks is as follows.........Joe

Ian the reply from David Marks re your problem.........

Joe hello,

This is a most unusual fault, one that I have not come across in this specific heat related form before.

We have had circumstances of V8 cars cranking but failing to start and these have come down to a problem with the gearbox rotary switch (applicable to 3.2 and 4.0 n/a cars only), whereby conflicting signals about gear select position are sent to the ECU and the fuelling is disabled.

These rotary switches are a series of micro switches in a housing and it is possible they are being affected by heat.

You will need to have the car scanned by a real time scanner in order to study the gearbox inputs along with the gear select inputs and compare them.

if you find, for example that the gear select says park but the rotary switch says drive, that is your problem.

As far as I am aware, only Autologic or Jaguar equipment and maybe the higher end Gendan options are able to do this.

Hope this helps

Mail back if required

Regards

[BrianG]

Hi ptopping,

This sounds suspiciously like a fault I had with a Rover SD1 Vanden Plas Efi 3.5 V8 some years ago. It would do the same as your car when hot if you stopped for more than a couple of minutes. Like yours, no fuel would be getting through and no amount of cranking would persuade it to start until it cooled down after about half an hour. I found that if you carefully poured water over the injector fuel rails it would start when hot, so the problem was a "vapour lock" in the fuel rails.

I eventually found that the under bonnet sound deadening material was not attached properly, and it was hanging down over both sides of the engine and thus keeping it unduly warm when stopped. I suggest you check the sound deadening on the underside of your bonnet to see if it's loose.

[ptopping]

Thank you all for your help. The problem has gone away at the moment, possibly due to the temperature outside not reaching as high. I will monitor the problem and report back. Regards Peter

[ptopping]

Here we go again with No Start. I don't know if it is coincidence but when it happens if I put the car into neutral it starts first time!!!! Spooky.

[robv12]

looking back through the postings, I see David Marks suggests the gearbox rotary switch, logic follows that if you shift into N and you get a start, that the rotary switch may well be at fault

I would suggest a scan of the car with Jaguar IDS or Autologic, this will indentify any faults

[J44EAG]

I had a 2.8 Capri that could vapour lock when hot. Eventually, I found the fuel feed pipe to be touching a rocker cover. Cable tied the pipe up off the cover and the problem disappeared.

Mike

[ptjs1]

As Rob has alluded to, if it will start in Neutral but not in Park, it can't be fuel vapour lock. It must be a problem with the rotary switch which locks out starting in anything other than Neutral or Park.

Good luck with getting it started.

Paul