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TR6 carb problem 73 tr6

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achtungeveryone

Jedi Hopeful
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well, i'm getting the car running again after being down for brake work. fuel is pouring out of the carbon canister lower hose fitting (no hose hooked up) when running. running very poorly. is this a symptom of a hung-up float valve.
also, since the carbon canister isn't functional, can i cap these fittings off?
any help is appreciated.
Chris
 
You need the vent for the carb to work properly, so don't cap. Sounds like a stuck floar and/or too much fuel pressure. Are you using a stock mechanical pump?
 
No you can not cap this nipple. It is the vent for the float chamber when the engine is idling.
TR6ARVVent-1.jpg


If you are getting gas from that point there's no question in my mind that the needle valve is not shutting off the supply from the fuel pump.
The needle valve could be stuck or less likely but possible the float has lost bouyancy because it has taken in fuel, thereby not rising high enough to close the needle valve
I've cleared up Needle Valves by removing the fuel line and by sticking the extension tube of a can of WD40, PB Blaster or the like all the way into the fuel inlet nipple and blast the needle valve while tapping on the wall of the float chamber with a 1/2" box end. The vibration seems to help break up the debris or varnish holding the valve open.

If it's not a sinking float you might luck up with this method.
Since you do not have the Anti Run-on Valve in use, did you cap off the nipple on the intake manifold's Banjo Fitting ?
 
thanks for the help, yes i just replaced the fuel pump with a new moss unit. i tried tapping on the bowl with a screwdriver handle but that didn't have enuf mass. will try a wrench and PB blaster method if that doesn't do it then i guess i could loosen the float bowl(s) and nudge em loose.

is the Anti-run-on valve on the canister? i had a thermoswitch of some sort on one of the radiator hoses but it was capped off and i did not use when i changed water hose set last summer. Also, i'm kinda vague on the intake Banjo fitting. just took a look with the flashlite and could not locate such a thing.
 
achtungeveryone said:
i just replaced the fuel pump with a new moss unit.
Click to expand...
That introduces a new possibility, that the new pump is putting out too much pressure. Not common, but it does happen from time to time.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] i tried tapping on the bowl with a screwdriver handle but that didn't have enuf mass. will try a wrench [/QUOTE]
Don't forget, those are thin castings of weak metal. You don't want to get too carried away with the tapping or you'll have a broken casting in addition to whatever the problem is.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] is the Anti-run-on valve on the canister? [/QUOTE]
Hanging down underneath the carbon canister, if it is still there.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] i had a thermoswitch of some sort on one of the radiator hoses[/QUOTE]
The TVS was intended to disable the vacuum retard when the engine started to overheat (like 200F). Not too important, especially if the vacuum retard has been disabled.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Also, i'm kinda vague on the intake Banjo fitting. just took a look with the flashlite and could not locate such a thing. [/QUOTE]
 

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The Anti Run on Valve (ARV)is mounted below the Carbon Canister (CC). You said the lower hose fitting on the CC had "no hose hooked up" and that's where the gas was pouring out.
That fitting would have a U-shaped hose attached to it with the other end of the U-shaped hose stuck onto the ARV. That's why I say the ARV is not being used.
If it's not being used then the Vacuum hose from the Banjo Fitting to the other hose fitting on the ARV is not needed.
If the vacuum hose has been removed then the nipple on the Banjo Fitting must be sealed with a cap or plug
The Banjo fitting is the fitting on the intake manifold that the Vacuum hose for the brake servo is attached to. The smaller nipple on the Banjo fitting is the fitting for the ARV vacuum hose.

I'm familar with ZS carbs and their internal components and although I am capable, I do not remove the float chamber with the carbs still mounted to the manifold.. One slip and you've upset the float level. Those that do so with mirrors, working like a dentist. more power to them.
 
yes, now i remember the ARV had a busted fitting that seemed to totally compromise the basic integrity of the system. found an old post from 2008 on this forum where we discussed the ARV...found poolboys informative post on the moss forum. good info. i'm now re-aquainted with my banjo fitting, had a hunch it might be part of the servo vac tee...hate to cap off anything called a "banjo fitting", might reduce the fun factor a bit. ya gotta do what ya gotta do.

i did remove the float bowl with carbs mounted, without a mirror, to replace that stupid plug in the bottom of the bowl. it would be nice if i could just remove this plug to free the float valve. what's the purpose of that thing??? to leak i 'spose...

i think the down time encouraged my float valve to stick open. if you let your cars sit this is what happens...after my 12 hr shift today i'll get back on this. THANKS for the great feedback.
 
That plug..It could be that the float chamber is a hold over from back when the ZS carbs had an adjustable jet mechanism sticking out of that hole ..
Replacing the O-ring around that plug is the only thing I'll do from underneathe without removing the carbs, myself.
This is not my original idea, but on the pair of carbs I'm using now on my 73, when I was rebuilding them,I put a layer of epoxy around the plug before I inserted it into the hole. A nice little bead of epoxy appeared around the external seam when I shoved the plug home. Once that dried in place, I put another layer of epoxy around the external perimeter of the seam.
I may be done with leaks...
 
There are also ZS float bowl bottoms that are made without the plug in the lower chamber - perhaps later on in the '70s for Jaguars or something like that.

Love it the way the gas leaks out right on the exhaust of a TR6....
 
well the wd40 straw in the fuel inlet a some tapping seems to have freed the hung up float(thanks skip), as i no longer have gasoline pouring out the vapor canister. i even had it idling good for a short spell but it wasn't to be for long. i lifted the air valve while running and the front carb rose in idle and the rear fell. i may need to inspect the diaphragms, if that doesn't show anything than i may send them to J Curto. i've always had a leak at the throttle bushings and his service looks pretty nice, a little pricey for me but if i pull the carbs i don't want to do it again because i (or someone else didn't get things right).
 
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