924Board.org

[John]

Hi all,

I can not start my car for 10 mins when it is hot, any ideas?

1983 N/A 1924 UK
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Many Thanks

Ross

1983 UK Porsche 924

[TonD]

When reading topic title, there's three words comming up:

WUR (Warm Up Regulator), also cold start valve, try using Search on those topics...must be great help
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Just remember I aint American nor English, so please don't blame my language

[kaffine]

Does it crank?
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80 924
80 931

The best desciption of an atom boils down to something unknown is doing we don't know what.
Sir Arthur Eddington

[dwak]

Sounds like you need to rig a manual cold start valve button. This is outlined somewhere on this board. Common problem. Simple jury-rig solution.
dwak

[Roger]

I am not 100% certian about euro cars. However the WUR and the cold start valve have little to do with hot starts on my 81 US spec car. The check valve (yours may be in the fuel pump) and the fuel accumulator are more likely the problem.
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1981 924 NA

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.

[Paul]

Usually this is caused by vapor lock when the fuel boils in the fuel injection lines. The cure is to run the fuel pumps long enough to get some liquid fuel back into the lines.

I just turn the key to the run position, listen for the pumps to run and stop,then turn the key off.

Repeat about 5 times, then try to start it.

[dwak]

[Vince Ponz]

Check fuel pressure.

My guess is the check valve.
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

[Paul]

Agreed, the lack of sustained pressure, causes the fuel to boil at a lower temp.

But in any case, running the fuel pumps is an easy work around.

[Lizard]

ok here are a couple of other things to check, pull the injectors and see if they are leaking, if they are it could cause it not to want to start when hot as it will drain the pressure out of the system and sometimes almost flood the engine, also checkthe fuel accumulators in the back just infront of the fuel tank, if they are leaking at the bottom again they will drain the pressure in the system causing abit of a start issue, now both of these might cause a tiny bit of a cold start issue as well but alot of people dont notice the cold start issues as they think the car is cold and are used to carburated cars that are normally difficult to start in the morn.
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3 928s,

[Rafael]

This is a post that i put some time ago.
Try with this before change nothing.

I´ve resolved the problem.
First of all, the botton like you have, only works when the engine is cracking after you left the key of the contac in normal position, the power to the cold start valve it´s of, and the engine need more fuel to run.
Try this, take the contats of the cold start valve apart disconect the wires and cut it (THIS IS VERY IMPORTAT because the wires that come from the car are given + or - to the valve) take + from the battery directed and the ground with the botton, so you have all the control to activated the cold start valve, and left it the time that you want and the time that the engine need to run well.
When the engine cold you must push the botton to start because know you have the control of the valve, and in warm starts you push the botton and when the engine start left it some time until you feel the engine is run ok.
If it works to you you can put it a fuse, and some reles like i did for the cold starts.
Try this and tell us.

[Roger]