1978 450 SEL 6.9 6.8L V8 w116
 

I have this classic Benz that I've taken from sickly and hardly running, as It was parked for many years, to alive and well. I've done a complete tune up and it's really running smooth. It starts immediately upon turning the key and after a brief high idle period it then kicks down like it's suppose to, to a smooth 750 idle. After approximately 5 to 6 minutes, it begins to hicough and sputter and it sounds like and acts like it's running out of gas. This continues untill it slowly chokes and putts and then dies. I have done this three times and all three times the car does the exact same thing at the exact same time. I feel like there must be a valve somewhere that upon heating up to normal running temperature is getting stuck open or stuck closed or something like that. Any ideas or knowledge of this problem will be helpful. I really need to get this baby on the road before school starts back up. My alternator is good, need help. Thanks.

Know nothing about that particular Benz but check the fuel pressure on the fuel rail if it has a schrader valve by using a tire pressure gauge if no other proper fuel pressure gauge can be had. Also monitor this pressure when the car starts to die, could be a faulty pressure regulator on the fuel rail, hope it helps
http://www.peachparts.com/shopforum/...bits_start.gif PeachParts Mercedes ShopForum > Technical Information and Support > SL Forum http://www.peachparts.com/shopforum/...o-here_ltr.gif Where to go from here? try this site sorry for the cut and paste , but maybe your answer is here.

that makes sense to me, thank you so much I really appreciate it.