| Author | Message | ||
     Robert Gardner Experienced User Username: bobg Post Number: 48 Registered: 12-2012 |
Turned on the ignition because I needed to raise the window, Immediately the garage was filled with the wonderful strong aroma of gasoline,I did not see any gas but I know it was from one of the overflow tubes because this has happened before when the car has been sitting for a long period of time. What do I need to do to prevent this from happening the next time I attempt to start her ? Not a lot of experience with carbs, so a picture would be worth a thousand words,Thanks so much 72 Shadow LRA13020 | ||
| Martin Taylor Frequent User Username: martin_taylor Post Number: 86 Registered: 7-2013 |
Hi Robert, Modern fuels tend to evaporate over time leaving varnishes and residue, this can cause the floats and needle valves in the carburettors to stick and cause said flood. The principal is the same as a toilet cistern, the float goes up and pushes the needle valve closed controlling the bowl level accuratly. Either use the car more often, add a fuel stabiliser if not or replace the needle valves with a new set. A light tap on the carbs may free it up. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1783 Registered: 5-2012 |
Hi Robert My guess is that after the car has been standing for a while, the fuel level drops in the float chamber due to evaporation. When you come to start the car the float is at an unusual angle and catches on the side of the chamber and therefore does not push up against the needle valve to regulate the supply of fuel. Next time you want to start the car after it has been standing for a while, turn the ignition on, which will activate the fuel pump, and then try tapping the side of the float chamber with the handle of a screwdriver to free off the (potentially) stuck float. If this fails it is a very simple procedure to replace the floats and needle valves on the carburetors on your car. It has the simpler SU-HD8 carbs. Since you have said you are not familiar with these carbs I have included a photo, below. The blue arrow points to the fuel feed pipe. If you follow it's path you will see how the fuel enters the carb through a small fuel filter and then the float chamber. The red arrow points to the lid of the float chamber. If you pull off the plastic pipes and undo the bolt, you can gain access to inspect the float etc. The float and lid just pulls off vertically. It's all very simple on these carbs.  | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1784 Registered: 5-2012 |
Martin raises a great point - I forgot about the stickiness of modern fuels. If you elect to remove the float chamber lid, I forgot to mention you will need to undo the fuel feed pipe at the carb inlet. A simple task, but let the car stand for a while to allow any fuel pressure to drop and also put a rag around the union to catch the small amount of fuel that will leak from the pipe when you undo it. Do this on a cold engine. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 1317 Registered: 4-2009 |
Modern fuels are a bit more aggressive than old fashioned stuff. Depending on the country that you live in - your type of fuel may not be the same as other users on this forum. In my country the fuel is now aggressive towards plastic floats and they quickly leak at the seams causing the floats to sink. The HD8 may have brass floats that don't suffer from this problem (although I have experienced many a brass float also leaking in the past). | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1787 Registered: 5-2012 |
Just to confirm the HD8 has brass floats, of the "non-hinged" variety.  | ||
| Patrick Francis Prolific User Username: jackpot Post Number: 169 Registered: 11-2016 |
The SUs on my Jag got fuel in them. SU told me that modern fuels eat the solder on old brass/copper floats, and supplied me with plastic ones! My Rolls has intact brass/ copper floats so far. | ||
| Robert Gardner Experienced User Username: bobg Post Number: 49 Registered: 12-2012 |
FUEL OVERFLOW FIXED, A light tightening of the nut atop the overflow tube did the trick !! | ||
| Guido Broich Unregistered guest Posted From: 81.174.11.26 |
Hi, let me put a new point to this thread, as argument is quite similar. I had my SS I sitting for some time and when I turned the key no clicking form the pumps. So I looked at them and no power on the electric line and no clicking anyway from the pumps if alimented form outside. I had a couple of new SU's on shelf and fitted them. Before coming to the wiring, I tested them with outside electric line and they started working fine, but once the gasoline fuel line was full the clicking went down but did not stop and after some seconds I had gasoline dripping from the engine bay .... Stopped all and now I have some questions: 1. Is there any electrical shutoff an the pump power line if pressure is up, or should the pump stop only by sheer pressure form the float closing? So should I do as above or have I to check also something in the electrics? 2. I will have to redo the electric line anyway, as no power is coming through. Some suggestions and caveat? Thanks! (Message approved by david_gore) | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 615 Registered: 5-2007 |
Guido, it may depend on your VIN number. At some point a cut-off safety circuit was added (perhaps at the Shadow ii ?). This was in the event of an accident to shut the fuel pumps down. I had this flooding problem also. It turned out to be a partial leak in the rubber fuel line between the pump and the carburettor. The pump kept going because there was little pressure in the line so it forced fuel past the leak into the carburettor. I didn't notice the leak because of the amount of petrol dripping everywhere. The rubber fuel line is quite short and is about 40cms forward of the pumps. My mechanic missed it when he put new fuel hoses in. He's probably not the only one to have left a 45 year old bit of rotting rubber in that spot. | ||
| Robert J. Sprauer Grand Master Username: wraithman Post Number: 396 Registered: 11-2017 |
Sitting for some time...Float issue | ||
| Guido Broich Unregistered guest Posted From: 81.174.11.26 |
Thanks! My VIN is LRX25741 so I gess it doesn not have and inertial stop. Anyway here important is that it is not just the pump which is too strong, but some structural leakeage somewhere in the front. By the way I am convinced that the car did run on one pump omly for some time, with lower pressure. Jeff I did change ALL pipes I found about 8 years ago, but will recheck the small piece you told, which I in effect do not remember right on the spot. (Message approved by david_gore) | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 616 Registered: 5-2007 |
Guido, good luck - you have the easy carbs to work on. It is probably the float bowl. I would disassemble and check the float isn't stuck or leaking then check the needle and seat and gaskets. Sometimes it's more than one thing. Even a loose nut. In any case it will help to give everything a good clean and perhaps check/change the filter isn't clogged. | ||
| Mike Thompson Grand Master Username: vroomrr Post Number: 420 Registered: 4-2019 |
If you are thinking of letting you car sit around, say 10 years, this is what your gas tank will look like.  And everything in it will look like this.  | ||
| Graham Phillips Frequent User Username: playtime Post Number: 79 Registered: 3-2019 |
G'day everyone,... OUCH!  Looks like 'Tar'. Graham. | ||
| Guido Broich Unregistered guest Posted From: 81.174.11.26 |
Thanks Jeff. I did in effect change the small filters and clean the carbs after getting the car in 2008, but after this time a good general clean is a good idea! Tomorrow will start and tell! The first thing I needed to know that there is no some strange pressure-check-and-cutoff sensor sitting in my Lucas looms which are my worst nightmare!  (Message approved by david_gore) |
