Mercedes Benz repair: merc benz sl500, vent valve, number search results

Question
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Followup To
Question -
if the car sits for about 2 weeks and you start it it will idle till you are dead but if you drive it about 11 miles it will back fire quietly and die


if you then restart it it will just back fire quietly as it cranks  if left for 20 or so minutes it will be fine untill left for a few more weeks without running

we know it has spark and presure the whole time but the spark fires at the wrong time after it stalls untill you leave it for the 20 minutes

do you have any ideas why it would do this and how to check what is wrong thanks a bunch


the car is a merc benz ls500 95 with the v8
Answer -
Best guess:
Fuel system leakdown = Bad Fuel Pump Check Valves.
Possible secondary issues, please read the following thread:

collapsed gas tank
http://www.mercedesshop.com/shopforum/showthread.php3?p=706567#post706567


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1995 Mercedes Benz SL 500
Part: Fuel Pump Check Valve
 Note:  2 per car
 Chassis: -F 110984
E3030-27620 Check Valve Bosch IN STOCK $14.23  
  
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc


Vehicle: 1995 Mercedes Benz SL 500
Part: Fuel Tank Vent Valve
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    Fuel Tank Vent Valve
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    Fuel Tank Vent Valve
Regeneration Valve
Also referred to as "regeneration valve".  

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc









thanks for the quick response

i believe we already checked the fuel pressure and it was fine plus it can run forever if it's not left for a long period of time once the initial 11 minute drive is done, and if it was the tanks pressure release valve it should die every 11 miles driven if i'm not mistaken.

we are laso going to check the wiring harnesses ive heard they cause many problems if they start to crack

ill have them take a look at that anyway but if you have any other info it would be much apreciated

also if you know where to get a factory manual for the car or the dvd that would be great

i will be waiting your reply and have a happy new year  

Answer
Fuel system leak down = Bad Fuel Pump Check Valves.

Fuel Pump Check Valves prevent fuel system pressure leak down, when the car is parked for weeks or months.

Read the last post of this thread RE: engine wire harness.

SL500 need advice !
http://www.mercedesshop.com/shopforum/showthread.php3?p=286047#post286047