Our 1973 +8 had symptoms of a clogged fuel filter - running and not running etc. Unfortunately the original AC filter is no longer available and I was supplied a (smaller) Mann filter. Once installed I took the car for test drive. It drove fine, but I smelled fuel and stopped. When I started the engine again, fuel was pouring out just underneath of the fuel pump. It seems as there is a kind of an overflow tube coming from the carburettor and ending up there...? But why is the fuel pouring out? Obviously we can't drive the car and I got it towed home and it's now sitting in our driveway. What on earth is happening?? Any help is much appreciated! Cheers /Finn
If you have SU carbs, the float chambers have overflow pipes, and inside each float chamber is a needle valve. If any dirt has found its way into the float chambers it will prevent the needle valve from sealing, and cause fuel to overflow.
But as you've replaced the fuel filter, make sure that the connections are sound.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4
As Dave suggested it seems that the needle valve in the carb float bowl may have picked up a bit of grit. the float determines the max height of fuel in the bowl, the float then lifting the needle into a position where it shuts of the fuel supply, and as the engine uses up fuel, the float drops to allow more fuel into the bowl until the fuel reaches the pre determined level...
If your fuel filter was clogged, either that suggests it has been in there a very long time or you have perhaps some contamination in the fuel tank....
When fitting a new fuel filter to an old rubber fuel pipe it is possible to nick the internal bore of the pipe and dislodge small particles of rubber, which will be after the filter, and thus find it`s way to the float bowl causing the issue you describe..
sometimes the grit can be dislodged with a few rapid taps on the side of the float bowl with a spanner,...
It is not a big task to remove the float bowl lid and observe the inner workings, though best research on the www if you intend to resolve what should hopefully be a simple enough issue..?
Ok seen this problem and it was due to a much higher volume / pressure being pumped by the fuel pump and flooding the carbs, find the correct pump or fit a fuel pressure regulator. Another problem is the needle valves may be also failing due to bad seating/sealing.
Yep high pressure is a good shout. it would also show up worn or badly seating needle valves also a float that's damaged will just be letting fuel flow through the overflow from the float chamber. In the good old days it just came out of a hole in the float chamber!
Like all above stated, I have Weber carbs fitted to my MOG. They had just come back from rebuild. It was send me mad. In the end I checked the pressure but the problem was the smallest bit of rubber from my hose. It unfortunately stopped the float valve from working. Best of luck with it and hopefully it will be a easy fix.
Hi again, it turned out to be punctured float unit. Got hold of a kit including the float unit, rubber O-ring and paper style gaskets. Got the spares from a MG spares shop locally, as the HIF6 carb is also used for the MGB V8. Removed the carb by just removing a few of the connecting rods, which provided enough access to the bottom of the carb. Cleaned everything by using gasket removed spray, installed the float and packed everything ( I did not use liquied gasket) and.... off we went ;.)
/Good to read that you solved your carb overflow..... You did not mention checking the all important float level height which may affect your air /fuel mixture, If interested you might beam up theis vid and jump in at 14 mins 48 sec, hopefully you will see that which I am typing of..
Any idea how the float came to be punctured and was it metal or plastic ?
I ask because modern fuels containing ethanol can attack various components on the fuel system, carburetor floats being one of them.
I've had a few issues on my classic cars related to modern fuels and I now go through the system replacing any "rubber" hoses and carburetor seals with E10 compatible items.
