Lately I have notice a black spot (looks like burnt rests of fuel) around the fuel rail thermal valve. First I thought it was one of the hoses, which did not adjust well, but it also affects to the injector clamp plate just below. Does anyone know what is happening?



Thanks a lot!
José

 

Firstly, there is NO fuel anywhere near that thermal switch, It is a "pad" style unit, and the threaded spigot on the rail is a blind hole, so NO chance of a fuel related fire, whoopee.

None of mine have them fitted. I deleted them, and HOT start is no issue at all. Some markets? require that as legislation, so only you will know that of course.
Messing with vac stuff is taboo I am told, not here luckily.

Some have reported, Orangeblossom is one, that the wax inside leaks out, so that may be the cause of the spotting.

 

Hi Jose

I had exactly the same problem and also took identical Photos to yours! as I thought that one of my injectors was leaking Fuel and this was driving me crazy until 'Grant' sussed it out, as like he said the Wax inside the Fuel Enrichment Valve had started to melt and was dripping molten Wax down on top of the injector

Even worse it was cutting off the Vacuum, which made the Car run so Rich, that She Started to Backfire

So I just pulled the Tubes off this Wax Stat and though I could have just joined them together, I replaced them with a single piece of Tube and cut the Wax Stat out of the Mix altogether and then once having done so unscrewed it from the Fuel Rail as most XJS's can run happily without it

My Car runs perfectly fine without this Wax Stat and since there is nothing behind it as it screws into a dead end on the Fuel Rail, then you may as well unscrew it from the Fuel Rail, as no Fuel is going to pour out

Sweet Smell Followed By A Massive Bang! (When the Wax Stat Melted)

 

Thank you very much for your posts, Grant Francis and Orangeblossom. Really really helpful. I will do the same.

 

Just to close this thread properly: some days after I discovered that there was fuel on the vacuum tube connecting the fuel pressure regulator to the thermal valve. It has the internal diaphragm broken, and this was the reason of the wax going out. Maybe fuel dissolves it. I changed both regulators and the problem disappear. It also starts better when hot.