Thermal Vacuum Valve

1990 XJ-S and 1991 XJ-S Classic Collection Coupes (US Spec, 5.3L V12)



Thermal Vacuum Valve (Part Number EAC 5086 or EBC 4600)

¾” Open End Wrench


The Thermal Vacuum Valve (also known as the Vacuum Thermal Valve and Fuel Injection Thermo-Time Switch) is mounted on the left side of the Fuel Rail.  If you’re going to take off the Fuel Rail or Air Rail, take this off first – I didn’t on my ’90 Coupe and ended up breaking one of the plastic male connectors going to the vacuum hoses – a $100 mistake (ouch!).  There are two vacuum hoses connected, mark which one goes where and pull them off.  Use the ¾” open-end wrench to get the valve off – don’t worry, no fuel will come out.


Thermal Vacuum Valve Location

(Viewed from Left Side)



The original Vacuum Valve on both of my cars was labeled with part number EAC 5086.  This valve has a small foam air filter under the cap – I just cut a small piece of foam I had to replace it on my ’91 Coupe…




I ordered a replacement from Rusty Cullens’ for $100.25 and they substituted part number EBC 4600, a valve with blue plastic and without a filter that so far seems to be fine…


New Thermal Vacuum Valve Installed




Questions/comments: Email me.