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chazr
United Kingdom
72 Posts |
 Posted - 03 Mar 2012 : 08:15:06
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| after running my engine for 10 minutes, then turning it off i have fuel leaking out of the carbs, open the fuel cap which releases a lot of pressure and the leaks stop, is there a breather pipe that is blocked . |
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1922
United Kingdom
549 Posts |
Posted - 03 Mar 2012 : 17:43:31
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The breather is in the cap. Do the carbs still leak if you leave the cap open?
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UMU
United Kingdom
343 Posts |
Posted - 04 Mar 2012 : 11:01:39
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When one of mine were leaking (and it was a bad leak, literally throwing it out when the engine was on), i found that the metal valve was stuck with a bit of grit and needed cleaning out with an air line. Sorry dont know what that part is called, but its the little brass valve thats included in the resto kit.
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chazr
United Kingdom
72 Posts |
Posted - 04 Mar 2012 : 21:23:56
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| no if you leave the cap open there is no leak at all. |
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bigt80
United Kingdom
1051 Posts |
Posted - 05 Mar 2012 : 08:27:05
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I'm not that au fait with why that should happen, but wouldn't the fuel pump hold back the pressure if, as it sounds to be the case, the breather is not working. I always used to get a good rush of air on opening the cap on my H120, but this never caused a build up of pressure at the carbs; but maybe fixed jet carbs cope better when this happens.
Sorry no answer, but just some thoughts!
Chers.
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JPSH120
United Kingdom
1178 Posts |
Posted - 05 Mar 2012 : 12:37:52
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quote:
Originally posted by bigt80
I always used to get a good rush of air on opening the cap on my H120
Me too! Although I never had a problem with leaking carbs?
I did however have a problem during the strip down phase of my recent resto work. Our bedroom is above the garage and one night I woke to a rather strong smell of petrol. I went down to investigate to find that the fuel had been leaking out of the end of the fuel pipe which was now disconnected from the filter. It was during the summer months so the warm weather must have increased the tank pressure and forced it out.
I will check the tank before re-fitting it back into the car to make sure any vents are clear.
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1922
United Kingdom
549 Posts |
Posted - 05 Mar 2012 : 18:31:57
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It's normal to have some pressure in the tank - I pretty certain the vent in the fuel filler cap is spring loaded, so it needs a couple of pounds of pressure to open it. If you disconnect the fuel pipe the pressure in the tank will normally squirt petrol all over you unless you open the filler cap before you start 
I think the fuel pump will just let any pressure through to the carbs. Its one way valves are designed to let the fuel flow in that direction.
I'm guessing the cap vent is blocked so the pressure gets too much for the float valves and it pushes them off their seats. Or maybe the float valves are a bit mucky and the extra little bit of pressure is enough to make them leak.
I'd try blasting some air through the filler cap vent (small hole in middle of underside of cap) and removing the float bowls and having good clean out (maybe try an airline on the fuel inlet first - it worked for UMU it might work for you).
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chazr
United Kingdom
72 Posts |
Posted - 08 Mar 2012 : 07:02:17
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| thanks for all the replies i will look at everything that as been suggested and try them all,nothing to loose everything to gain. thanks chaz |
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stromberg carbs
