Smithengineered Posted January 6, 2023 Share Posted January 6, 2023 So after the first full fill up the Caterham is dumping fuel from a line that runs to open air. The bung is on the top middle of the gas tank. Clearly this should not be happening and I’ve tried siphoning 1.5 gallons out with it still happening. Any advice? Link to comment Share on other sites More sharing options...
Davemk1 Posted January 6, 2023 Share Posted January 6, 2023 It looks as if that is a fitting for a fuel tank vent hose. One would typically fit a piece of rubber hose and run it up above the tank as high as possible. The hose can be left open on the end or you can fit a filter (a good idea to keep bugs and stuff out of it) and this will allow for air to replace the space taken up by used fuel without it creating a vacuum. It will also allow the air to escape when the air in the tank expands due to a temperature change. If you get the end of the vent hose as high as possible fuel should not come out of it. dave Link to comment Share on other sites More sharing options...
MV8 Posted January 6, 2023 Share Posted January 6, 2023 A similar discussion: https://usa7s.net/ips/topic/13971-wdbs-caterham-super-seven/ Link to comment Share on other sites More sharing options...
Smithengineered Posted January 6, 2023 Author Share Posted January 6, 2023 17 minutes ago, Davemk1 said: It looks as if that is a fitting for a fuel tank vent hose. One would typically fit a piece of rubber hose and run it up above the tank as high as possible. The hose can be left open on the end or you can fit a filter (a good idea to keep bugs and stuff out of it) and this will allow for air to replace the space taken up by used fuel without it creating a vacuum. It will also allow the air to escape when the air in the tank expands due to a temperature change. If you get the end of the vent hose as high as possible fuel should not come out of it. dave It’s running up front just under the alternator currently open air and yesterday dumped quite a bit of fuel just pushing the car out of the garage. Link to comment Share on other sites More sharing options...
Smithengineered Posted January 6, 2023 Author Share Posted January 6, 2023 16 minutes ago, MV8 said: A similar discussion: https://usa7s.net/ips/topic/13971-wdbs-caterham-super-seven/ Thanks Link to comment Share on other sites More sharing options...
MV8 Posted January 7, 2023 Share Posted January 7, 2023 I take it this has not been driven yet and you took the tank out to clean out the old gas? This must have an evap tank up front. If the end of the fuel hose next to the alternator is not connected to anything, that is probably where it goes but take a pic of wherever it goes. Link to comment Share on other sites More sharing options...
Smithengineered Posted January 7, 2023 Author Share Posted January 7, 2023 1 hour ago, MV8 said: I take it this has not been driven yet and you took the tank out to clean out the old gas? This must have an evap tank up front. If the end of the fuel hose next to the alternator is not connected to anything, that is probably where it goes but take a pic of wherever it goes. Removed the tank a few weeks ago to replace the fuel pump gasket add a Aero Filler and put a few gallons of gas in it to check for leaks and drive it around with no issues. I decided to do a full tank fill the other day and this is when the problem started. The breather hose off of the fuel filler neck goes to the evap canister and there is one male connector that is not connected to anything coming off of the evap. I originally thought that hose should be connected there, but now after having fuel dump out of that breather I’m glad I didn’t connect it. Link to comment Share on other sites More sharing options...
MV8 Posted January 7, 2023 Share Posted January 7, 2023 (edited) The evap can should have a hose connection to the engine directly or through a solenoid controlled by the ecu. I think you can cap the tank vent port if using the filler vent port which should be more effective or just use the filler port to make a looped vent pipe without a functioning evap can. There should also be check valves and restrictors in any evap system. I don't know that the evap sys is sourced from an SVT ford. I don't have a cat to look at. Post pics of the system components. Check out the vent routing (no evap can in use) in the pic in this link: https://www.caterhamlotus7.club/forum/techtalk/workshop-notice-371 Edited January 7, 2023 by MV8 Link to comment Share on other sites More sharing options...
CarlB Posted January 7, 2023 Share Posted January 7, 2023 MV8 is giving you good advice. You need a diagram of the evaporative emissions system to make sure everything is hooked up properly. I have never seen one that did not include electrically controlled valves. If you want to eliminate the system, you need to make sure the tank is vented. It may or may not vent through the gas cap. It probably isn't because the car has an evaporative emission system on it. The point of the system is to vent the vapors into the engine. The engine should only get vapor not liquid fuel. If you install a vent to atmosphere line you need a one-way valve to prevent fuel leaking out if the car goes upside down. If you look on Summit Racings web site, there are pages of options for rollover valves. Link to comment Share on other sites More sharing options...
Smithengineered Posted January 7, 2023 Author Share Posted January 7, 2023 3 hours ago, MV8 said: The evap can should have a hose connection to the engine directly or through a solenoid controlled by the ecu. I think you can cap the tank vent port if using the filler vent port which should be more effective or just use the filler port to make a looped vent pipe without a functioning evap can. There should also be check valves and restrictors in any evap system. I don't know that the evap sys is sourced from an SVT ford. I don't have a cat to look at. Post pics of the system components. Check out the vent routing (no evap can in use) in the pic in this link: https://www.caterhamlotus7.club/forum/techtalk/workshop-notice-371 It has a solenoid controlled by the ecu. I capped the line that was dumping fuel as a test and took it out on a 20 mile drive. Removed the gas cap to see how much pressure buildup there was and there was hardly any, but I’m also back on a half of a tank so I’ll have to test again with a full tank. Thanks Link to comment Share on other sites More sharing options...
Smithengineered Posted January 7, 2023 Author Share Posted January 7, 2023 2 hours ago, CarlB said: MV8 is giving you good advice. You need a diagram of the evaporative emissions system to make sure everything is hooked up properly. I have never seen one that did not include electrically controlled valves. If you want to eliminate the system, you need to make sure the tank is vented. It may or may not vent through the gas cap. It probably isn't because the car has an evaporative emission system on it. The point of the system is to vent the vapors into the engine. The engine should only get vapor not liquid fuel. If you install a vent to atmosphere line you need a one-way valve to prevent fuel leaking out if the car goes upside down. If you look on Summit Racings web site, there are pages of options for rollover valves. Thanks for the info! Link to comment Share on other sites More sharing options...
speedwagon Posted January 8, 2023 Share Posted January 8, 2023 If there is liquid coming from that line, it is not suitable for the vapor system. For the vapor system you need vapor only. Any outlet that raw gas can splash from is unsuitable. ( try over filling your modern auto till fuel shows at the gas cap and you will soon have raw fuel coming out of the canister vent). Usually a line taped to the filler pipe is at the highest point but should be shield from splashing gas while filling and possibly routed to a higher point so that any gas that may get into it drains back to the tank. PS- I know this because-- " when we get older we do not get wiser, we just have a larger repertoire of mistakes we made". john Link to comment Share on other sites More sharing options...
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