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fuel tank breather

PostPosted: Mon Jul 19, 2010 8:22 pm
by tablets32
hi fellas,

had a really strong petrol smell in the garage ever since i put some in the car, discovered today that the tank breather pipes are not fitted! the manual says to drill holes, fit the pipes to the stubs , lay the pipes over the tank, feed them vertically down the body, and and on seems like a lot of bother to me. are there any alternatives to the original system?

also different topic but my wiper switch is the old pump type. it has three spade connectors, the replacement loom and the wiper motor has four wires, the light green wire cannot be connected to the switch. what does this wire do? are switches with four spades available? if yes who from? if no is there an alternative?

just to explain the car is a 1968 +2 which i have only had a short time, it has a ford 1600 xflow engine, twin dellorto 40s, the original gear box, a new lotus chassis and electronic ignition. it is not completed yet. i still have to fit the headlining, interior lights, and new carpets. as well as sort out the wiper switch!



Re: fuel tank breather

PostPosted: Mon Jul 19, 2010 9:50 pm
by bob_rich

sometime ago I had a few questions on the fuel tank. the link attached gives a bit of useful info. there are other modes that can improve the situation. I would certainly add the pipes ( or do one of the improvements) because if you do not have any the vapour will enter the car very easily.

hope the link below helps



Re: fuel tank breather

PostPosted: Tue Jul 20, 2010 1:26 am
by stugilmour

You can see in the other thread how the stock vents go under the head liner. They were required to prevent fuel spillage with the car rolled over and to allow for filling the tank to the top even if on a slight angle. The problem is the filler coming in about a third of the way from the top of the tank, which makes re-fueling to the top very slow if the vent tubes are not in good shape and open. The problem is the large vent tubes vent a lot of vapor.

The Lotus Club mod that is in the second thread gets rid of the fuel odor when the car is sitting. I just completed a very similar mod this weekend, and I now have no fuel odor in the garage. I had to replace the tank due to a leak (different issue) and install a new filler nipple with a vent nipple threaded into the side of the filler pipe. You can make this up or purchase from Spyder (if they still have them). Note the Lotus Club mod still uses one vent line routed under the head liner, but because it is smaller diameter it does not vent as much fuel vapor. I have not re-fueled directly from a pump yet, but had no issues filling from gas cans so it all looks good.

The wiper switch and motor is quite confusing. Note Lotus did not use Lucas standard wire colours, so these may be different on your car than the attached link. Here is a link that I found helpful on how the thing works. I am assuming you have the two speed wipers with self parking.

Note the motor plug in the above is oriented as looking at the motor connector plug. IIRC, the illustration in my workshop manual wiring diagram is upside down and oriented looking face on at the motor plug lead, so they are a mirror image of each other.

For my car, here is a quick table of the Lucas standard wire colours referenced in the attached, and the corresponding Lotus colours in my car. Your car may have different colours, but the functions should be similar. You can get a plug for the wiper motor from the following on page 17 of their catalog:

Lotus.....................Lucas Colour..............Motor Plug Contact........Remarks
Black.....................Black........................1 Ground
Blue/Yellow.............Brown/Lt Green..........2 Park........................See note about wiper switch in document
Lt Green.................Blue/ Lt Green...........3 Second Speed
Green....................Green........................4 Live
Yellow....................Red/Lt Green.............5 First Speed

Re: fuel tank breather

PostPosted: Tue Jul 20, 2010 7:27 am
by tablets32

thanks for all the info men, think i will go with the lotus mod for the breather, the info about the wiper switch leads me to think the replacement loom is for a later model +2 than mine. as the wiper blades are not fitted yet i`m not really sure if i have one or two speeds. i will have to look further. where do you guys get dellorto spares from, mine are leaking petrol due i hope to lack of use, gaskets breaking down etc. the car has been off the road for years, and although the engine runs it is very lumpy. i fitted electronic ignition, and have tried to set the timing but i think the camshaft is not standard, so finding the right setting is taking time. the po had the car for 18 months. but doesn't know anything about the camshaft.

thanks again.


Re: fuel tank breather

PostPosted: Tue Jul 20, 2010 8:34 am
by Robbie693

Re: fuel tank breather

PostPosted: Tue Jul 20, 2010 10:49 am
by kstrutt11
Mine has a 1/2" pipe fitting clamped into the filler neck then domestic copper pipe and small lengths of hose to link the the vent pipes, in the top of one of these copper pipes I have soldered a length of copper brake pipe which is then vented to atmosphere behind the diff.

This works a treat fills up fine (air vents through the open filler cap) and the small bore pipe doesent allow any noticible fumes.