I have been having gas leaks from the injectors o-rings for the past few weeks.
I have Siemens 720cc injectors in KG rails primary fuel rail. The original o-rings that came with the injectors when I bought them got dried up and dont seal properly anymore. I have been trying different size o-rings from Ford, to Mazda to jobber and the list goes on.

Does anyone out there with the same setup or has to the knowledge or knows the part number. Please tell me WTF size o-rings do I need ?

 

If they are KG rails they use a Bosch 14mm diameter top. The factory rail has an 11mm diameter o-ring at the top which is much thinner looking.

Go to the auto parts store and tell them you need injector o-rings from like a 2001 F-150, or a 93 Dodge Ram truck, whatever. Most injectors for American and European cars have 14mm o-rings on the top.

 

you mentionned o-rings from a 2001 Ford f-150, Which one ???

From the V6 4.2L, the V8 4.6L, or the Triton V8 5.4L ???

 

I think the 4.6 is fine. they're probably the same across engines actually. go to the parts store and ask them to open the box so you can see the o-rings before you pay for them. it will be pretty obvious, especially if you bring one of the injectors with you.