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TR6 ZS carb issue

Moss Motors
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jacko241 Avatar
jacko241 Gold Member Joe Jacalone
Saint Augustine, FL, USA   USA
I am having trouble with a TR6 flooding. Car will start and run fine for the first 5 minutes or so, then it begins to load up and stall. When I lifted the damper, fuel was flowing freely out of both jets. I pulled both carbs, and checked the floats,and they float fine, and no liquid inside. I replaced the needle and seats, which were Grose-Jets, with standard units. No good, same thing. I then lowered the float level from 17mm to 20mm. The front carb seemed better, but rear still flooded. I then raised the rear another mm, no change. Also installed inline press. regulator, to reduce pressure, no change. Any ideas?


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BEB73 Brent B
Punta Gorda, FL, USA   USA
A bit more history, please. Had the car been sitting for a while before that running? Flooding happened after the chokes were pushed in? thx

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jacko241 Avatar
jacko241 Gold Member Joe Jacalone
Saint Augustine, FL, USA   USA
Car has been driven regularly, chokes are not being used, but appear to be functioning properly.


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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
You've installed a pressure regulator while using OE mechanical fuel pump?

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jacko241 Avatar
jacko241 Gold Member Joe Jacalone
Saint Augustine, FL, USA   USA
Yes, to confirm that high pressure was not the cause.


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LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
Are you running an electric fuel pump? If so what make and model and how much pressure does it put out?

Any recent changes to the fuel system?

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jacko241 Avatar
jacko241 Gold Member Joe Jacalone
Saint Augustine, FL, USA   USA
I just answered Barry above and said it is the mechanical pump.


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TuRtle5 Avatar
TuRtle5 Kevin Kelly
Absecon, NJ, USA   USA
1949 Triumph 2000 Roadster "Coral Mistress"
1959 Triumph TR3A "Drandulet"
1962 Triumph Vitesse "Ohtoseethelightofday"
1968 Triumph TR250    & more
Fuel filter ? dirt getting into the float valves

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LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
Ok, then the OEM pump can’t produce too much pressure and the regulator is unneeded and could cause problems.

Got to be the float valves not seating, float setting too low or gas in the floats. No other reason for gas to get past point.

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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
Adding to Kevin above, replace fuel hoses between fuel pump [or 'post pump' fuel filter] and carbs. Material from inside hose wall can slough off and prevent complete closure of influent to bowl shut-off.

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jacko241 Avatar
jacko241 Gold Member Joe Jacalone
Saint Augustine, FL, USA   USA
In reply to # 1599684 by LFMTR4 Ok, then the OEM pump can’t produce too much pressure and the regulator is unneeded and could cause problems.

Got to be the float valves not seating, float setting too low or gas in the floats. No other reason for gas to get past point.

I put the regulator in AFTER the problem began as a test, it is no longer installed. No gas in the floats, put them in a can of gas and they floated for hours, 2 different float valves, multiple float settings.
Forgot to add I am 40 year plus ASE certified master tech, rebuilt hundreds of carbs over the years, just wondered if anyone had a specif weird issue that was similar.



Edited 1 time(s). Last edit at 2019-03-02 02:05 PM by jacko241.


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ckilmer Avatar
ckilmer Callen K
Orangevale, CA, USA   USA
The only comments I can make are checking the bowl when you remove it for foreign material that may be causing the float valve not to seat, making sure the tab on the float is parallel to the carb base when the valve is closed and making sure the gasket between the valve and carb body is in good shape and not letting fuel leak by. Since you have the regulator, you could make a bench set-up with an electric fuel pump to test the carb with the bowl off and either invert the carb and let the weight of the float close the valve (may need to add finger pressure, not sure) or just lift the float by hand in with the carb upright position.

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trrdster Avatar
trrdster Wayne Tate
Spencer, NC, USA   USA
1949 Triumph 2000 Roadster
1970 Triumph TR6
1978 Triumph GT6 "Scooter"
1978 Triumph Spitfire "Scooter"    & more
Joe, if you have the original pump with the lever, or a electric like Callen said. Take the bowl off and pump away and wee what it takes on by finger to lift the float and get the gas to stop.
With all you have tried, it's got to be right there. You would not be the first to get new parts that didn't work. Let us know what you find.



Wayne
1970 TR6
2000 Jaguar XK8
1949 Triumph Roadster 2000
1978 Spitfire (rust victim)
1971 GT6 (tarp covered for 12 years, rusted inside out)
1980 Spitfire (getting all the good GT6 parts, all poly suspension and Spax shocks)

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andy303 Avatar
andy303 Gold Member Andrew Blackley
Chardon, OH, USA   USA
Another possibility is that the vent of the float chamber is blocked by debris or a gasket fitted the wrong way around, blocking the vent. Try blowing air through the vent hole in the top of the chamber.

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BEB73 Brent B
Punta Gorda, FL, USA   USA
Yes, I did have something similar. The vent from the carb bowl to the inside the air filter was blocked. Metal plug in my case, but a gasket over a port would do the same. Would over-pressure the chamber and cause a rich-at-idle/flooding condition until "cool" gasoline arrived.

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