Hi All,
I have been away for some time… Distracted by BMWs… Anyway I am trying to help a local retired guy here with his owned-from-new 1976 XJ6.
Its over fueling… I am trying to correct the local workshop modifications of extra pipes and Toyota parts…
I see this valve thing in right front corner of engine bay. It’s got one permanent live going to it, the thing just dangling… What is it and how is it meant to be connected??
It’s the Anti-Run-On Valve. Basically when the engine is switched off and oil pressure is present it applies a vacuum source to the vents of the carbs to prevent fuel from entering the cylinders and the car from dieseling or running-on. One terminal is 12v through a contact in the ignition switch and the other is switched ground through a normally open oil pressure switch that only works when there is pressure.
Nothing to do with over-fueling especially if it’s disconnected.
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It sure looks like the anti-run-on valve, David - as Mike says.
However, it is supposed to be powered only with ignition ‘off’. Turn the ignition out of ‘off’ and check for power - there should be none. Also check at the carbs for vacuum spigots/hoses at the carb bowls…
While the engine is turning, giving oil pressure; a special oil pressure switch is grounded. With ign ‘on’ and engine running, there is no power to the valve; no vacuum is applied to the carbs and the engine runs normally. As ign is turned to ‘off’ and the engine winds down; the valve applies manifold vacuum to carb bowls - preventing fuel entering the manifold.
As one wire is disconnected, the valve is not active and is, as Mike says, not causing overfuelling. If it was active, the engine would not run…
While ‘extra pipes and Toyota parts’ may be involved in overfuelling; check the ASC or AED, whichever is fitted, for presence, function or PO interference. Another possibility is of course carb float levels - or general tuning of the carbs…
frank
xj6 85 Sov Europe (UK/NZ)
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BTW I see you’re in Malaysia but if this is a US spec car with Stromberg carbs it would have the troublesome water-choke system which, if not working properly, can cause overfueling. Also if someone tried to ‘de-smog’ the system by disconnecting the EGR valve from this model of Stromberg carb it will almost certainly cause a rich condition. A '76 series 2 would have all the fun emission controls and those carburetors are very much a part of it. They are designed for the ingress of extra air from the EGR system.
Obviously it would be very hard to tell what exactly is wrong without more detail but if you have Strombergs, take a look at those areas.
~Mike
Hi Mike,
its a euro spec car with HIF carbs, still looks complex compared to my '73 US-spec E-type.
First i’ll cleanup the vacuum plumbing and replace the rubber fuel lines…then I can see if it is the AED or maybe a flooding carb causing the fuel issue…
thanks all for helping identify this anti-runon valve
dave