Thermo time switch?..

Thermo time switch?..

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Discussion

CJD2005

Original Poster:

98 posts

129 months

Tuesday 15th April 2014
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Hi All, think I need a new thermo time switch, have not tested it fully yet but when my engine is hot and try to re start say 10-15 mins later it ticks over like it's flooded. When engine is cold starts no problem first turn of the key.

Any suggestions on where you can buy a new one from?.

Cheers

phillpot

17,105 posts

182 months

Tuesday 15th April 2014
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No idea if these things are now rare and/or expensive but judging by this one on Ebay perhaps they are?

nigel100

11 posts

130 months

Tuesday 15th April 2014
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I have been told that a number of owners who have that problem fit a separate button to energise the '7th injector' bypassing the thermo switch altogether. In cold weather the switch is pushed in for a second or two when turning over on start up giving the extra fuel needed (somewhat like a manual choke). I have the same problem but have not got round to fitting the switch I have purchased (among other things). At the moment the 7th injector on mine is unplugged as it is not needed in the summer months and I don't use it in the winter.

Other more experienced owners may be able to help more.

CJD2005

Original Poster:

98 posts

129 months

Wednesday 16th April 2014
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Thanks for responses, thought this would be the case, I saw that one on ebay but with it been a used one was not keen. 'Came off a good running engine' does not mean he had no trouble starting when hot! ...may just have to bear with it and leave it more than 15 mins in future..
Chris

phillpot

17,105 posts

182 months

Wednesday 16th April 2014
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From Nigel's suggestion if you pull the plug off the switch once engine is hot and it then starts ok when hot that will prove if it is the switch playing up?

CJD2005

Original Poster:

98 posts

129 months

Friday 18th April 2014
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So I disconnected the plug off the thermo switch and guess what when the engine is hot and
you go back to it around 10 mins later it's like a bag of hammers and stalls! Oh dear! A bit lost now......

Loach1

431 posts

140 months

Saturday 19th April 2014
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Stalling could be a leaking injector, accumulator or check valve releasing the line pressure while the car sits. Try and bump the fuel pump a couple of times next time before starting.

The other culprit could be the warm-up regulator. This needs a fuel pressure gauge to check correctly, to make sure that your hot and cold control pressures are to spec. Some mechanics have a gauge set and knowledge of the Bosch CIS, but most don't. Look for someone in their 50's!

CJD2005

Original Poster:

98 posts

129 months

Saturday 19th April 2014
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Thanks For the info, one thing I did not try was disconnecting the cold start injector ( blue plug )Even with the switch disconnected ( brown plug ) would this still work. I understand that the cold start works also when the engine is hot, if the engine does not start after so many seconds?. Think it may have to go to a specialist.

Loach1

431 posts

140 months

Saturday 19th April 2014
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CJD2005 said:
Thanks For the info, one thing I did not try was disconnecting the cold start injector ( blue plug )Even with the switch disconnected ( brown plug ) would this still work. I understand that the cold start works also when the engine is hot, if the engine does not start after so many seconds?. Think it may have to go to a specialist.
Correct. The cold start injector will fire every few seconds if the engine is struggling to catch. Disconnecting will confirm if you have a flooding issue or not.

CJD2005

Original Poster:

98 posts

129 months

Saturday 3rd May 2014
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I have checked the cold start valve by removing and it appears to be working correctly. The check valve is this within the fuel accumulator ? I know you can buy a new accumulator off the capri club website however are around £150! . To check the injectors for dribbling can you just pull the fuel line off the injectors?

Loach1

431 posts

140 months

Saturday 3rd May 2014
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The check valves I have seen are on the output side of the fuel pump, screwed into the body of the fuel pump. It's the piece that the banjo fitting slides over. I don't think the check valve is your problem because I had a completely failed valve and all it meant was starting took a second or two longer than usual.

To check the injectors you need to remove the intake plenum, unbolt and slide out the injectors. Then drop them in a bucket, being careful not to stress the hard to replace fuel lines, swap the silver light relay for the purple fuel pump relay and turn on the ignition to make the pump run continuously. Then you can lift the flap in the metering head to make the injectors flow. Check for a nice atomised conical spray, then turn off the pump and watch for drips.

An easier check would be to put a pressure gauge inline where the fuel line comes into the metering head, but finding all the right fittings is a bit of a pain.

CJD2005

Original Poster:

98 posts

129 months

Monday 5th May 2014
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Turning the ignition on 2-3 times ( bumping the fuel pump ) seems to solve the hot start issue for the time being. Not going to take the injectors out, however will a new accumulator help?

Loach1

431 posts

140 months

Monday 5th May 2014
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A new accumulator might help if it is leaking through the diaphragm. I might be wrong, but I don't think it has anything in it other than a piston/diaphragm and spring. This is just being used to store up a bit of fuel pressure to smooth out the delivery from the pump, and keep a bit on hand for starting the engine. If you have a leak either back to the tank (fuel pump check valve, or leaking fuel pressure regulator), or into the engine (fuel injector), the accumulator's pressure will decrease rapidly once the pump is switched off.

It's quite a common issue with S1's unfortunately and is hard to find the cause without swapping parts or pulling the injectors. Maybe the easiest place to start is to pull the pressure regulator out and replace the o-rings, then the next step would be to replace the check valve on the end of the fuel pump. It looks like this: http://www.ebay.com/itm/New-Bosch-Fuel-Pump-Check-...

It might not be main fuel pressure related though, it could be that your control pressure is too high, resulting in a lean start condition. That could be trash in the inlet side of the WUR (check the little strainer under the banjo bolt), or just in need of an adjustment by someone that knows how to set pressure on Bosch CIS.

CJD2005

Original Poster:

98 posts

129 months

Tuesday 6th May 2014
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Thanks for all your help, I can probably do the check valve, accumulator, o rings and check the strainer, but will probably get the pressure checked by a specialist.

The o rings ... Just need a bit of clarity on these, are they on the banjo bolts.?

Thanks again.

Loach1

431 posts

140 months

Tuesday 6th May 2014
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CJD2005 said:
The o rings ... Just need a bit of clarity on these, are they on the banjo bolts.?
There are 3 o-rings in the fuel pressure regulator. Here's a picture to show you where they are:



The regulator is in the metering unit, right next to the fuel inlet line.

If you remove the banjo bolts, make sure you have new crush washers available or you may spend a while trying to stop leaks.