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Odd starting behaviour

DavidL

DavidL

Active member
I don't normally do stop start trips in the 44T but this weekend I have done some and it has thrown up an odd thing.
From cold no problems at all.
From normal running, stop for a few minutes (petrol etc) no problems.
From normal running, stop for 15 minutes to about an hour, spins freely but won't catch. Pop the bonnet and leave it for 5+ minutes and it starts.
It could be DME or one of the fuel sensors but it seems to be related to the engine temperature.
I'm a bit purplexed to be honest - it makes trips a bit difficult!
David
 
ORIGINAL: pauljmcnulty

I'd change the DME relay anyway. If it's not the problem then it will be one day! [8|]
Click to expand...

I've had a read of Clarks and I shall be ordering a new one tomorrow. It certainly sounds like the early warning stages. Fingers crossed.
Must ring Bert tomorrow!
 
You may find a local enthusiast has one you can borrow to help diagnose it ... you'd be welcome to mine but you're nowhere near London.


Oli.
 
ORIGINAL: zcacogp

You may find a local enthusiast has one you can borrow to help diagnose it ... you'd be welcome to mine but you're nowhere near London.


Oli.
Click to expand...

Thanks for the offer Oli. I've ordered a new DME from Porschaparts anyway so I will install that when it arrives. If all esle fails I'll have a spare then which is no bad thing. Reading Clarks it seems likely this is the issue. We'll see.
 
Ok so sadly it isn't the DME, so now I have a spare.
Any thoughts? Haynes (I know) suggests a clogged air filter - why would that affect hot starting?
 
Actually the car doesn't want to start at all with the new DME - its a new 993 part no.
I assume its just a case of swopping them over. Certainly swopping them back works fine.
I'll try again tomorrow and if I get the same result they can have it back.
 
Thats the one I have as well .. I think its an upgraded one (But I am open for correction [:D]) Faye had a similar problem where it took at least 7-12seconds of cranking to start when warm. Cold it took about 2 seconds. This was due to a dying fuel pump. We sussed this using the Cannell manual Vol 6 section 24 page 80

http://www.cannell.co.uk/Manuals.htm

This might not be the problem but its worth checking anyway [;)]
 
ORIGINAL: VanhireBoys

Thats the one I have as well .. I think its an upgraded one (But I am open for correction [:D]) Faye had a similar problem where it took at least 7-12seconds of cranking to start when warm. Cold it took about 2 seconds. This was due to a dying fuel pump. We sussed this using the Cannell manual Vol 6 section 24 page 80

http://www.cannell.co.uk/Manuals.htm

This might not be the problem but its worth checking anyway [;)]
Click to expand...

Donal,
I'm wondering if I have the same problem. I hadn't left it cranking for that long before, but I tried for 10 secs and it started.
More under bonnet stuff it seems.
Where do i get a fuel pressure meter?
 
ORIGINAL: DavidL

Where do i get a fuel pressure meter?
Click to expand...

I think its a VW/Porsche "Special tool" [:mad:] There is a plastic cover you take off the front of the fuel rail exposing a nut. What I done was take the nut that I took off the fuel rail (watch the wee sealing ball...!) and brought it to a JCB dealer who makes up hydraulic hoses. He was able to make up a proper fitting and had a guage which read to 60psi which done the trick. I think we paid him €30 [;)] If you even got an air pressure guage off an airline or sommit the hydraulic hose man would be able to bodge the guage on for you... Air pressure guages dont like long term use with petrol but....!

With the DME bridged, fuel pump running constantly and the engine off the pump should make at least 2.3 bar or 33psi and a max of 2.7bar or 39psi. With the car ticking over it should read 2bar or 28-30psi. We were only making 20psi and the pump was struggling on the static test....[:D]

1bar = 14.5psi

It may be a different issue but at least you can say your fuel system is in good nick which is a starting point.



 
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