730 hot start issues.

[EC Methven]

Hello all and thanks for such a nice forum.

I have read most of the threads relating to this issue but just want my own with my own problems talked about.
My 1990 730 auto has starting problems.
If I use the car every day its mostly fine, but if I leave it for a few days it gets hard to start and runs very poorly when it does start.
on a day it starts fine I can run it a few miles then it will start to missfire and just not run very well.
when I reach my destination and stop the car it wont start for an hour until the engine is cold again,
then it will run poor for a few minutes and then run like it never had a problem,just very smooth like it should.
On a day where it wont start I will have to give it throttle to start it and it will missfire and backfire a bit
and wont really take revs past 1500 - 2000 unless you ease it up.then if you stop it it will not start for an hour or so or just start and run rough.

temp guage is fine. all other things are fine.

I have read about the checkvalve replacement ,does anyone know where to get one in the UK?
I have also read about a leaking injector. anyone think it might be this ?

hope to get some replys soon. its driving me .
thanks

EC Methven

[shogun]

You said you checked almost everything.
So I would propose to check the fuel pump
http://www.bmwe34.net/e34main/mainte...e/FuelPump.htm
The pressure should be fine.
Then of course the check valve
http://freeweb.siol.net/caposiol/ventil000.jpg
http://freeweb.siol.net/caposiol/ventil001.jpg
http://freeweb.siol.net/caposiol/ventil002.jpg
http://www.bimmernut.com/%7Ebillr/im...checkvalve.jpg
I think the latest p/n is 16141179282


Or the fuel tank de-aeration valve, here as sample pic from 735
http://www.realoem.com/bmw/showparts...12&hg=16&fg=10

The fuel tank de-airation valve should have a resistance of 45+/- 20 Ohm.
It is closed when no power is applied.
You can check the breather valve function also by removing the fuel tank cap after driving. If you hear a hissing sound out of the fuel tank, it might be the breather valve.
As for where to get those parts cheap in the U.K., ask here
http://www.bmw7resource.co.uk/

BTW: is that a 730 R6 = straight six or a 730V8 engine?
The 7 was available with both engines. First straight six, then the V8 730 with M60 engine.
Depends on the year/month of production.