Old Crap Fuel - Draining Fuel Tank advice please.

[richardcox_lotus]

Dearest collective

The car is now back from its repaint, & looks fantaaaaastic. However, doesn't drive so well, as the fuel tank wasn't fully drained before the job commenced. As the job took many months longer than even I envisaged, the fuel no longer has the pop it should have. I topped the tank up with fresh & have run the car for about 120 miles since. As I'm back to the last 1/4 of a tank its misbehaving again so I'm presuming I should drain the tank of the remainder & refill with fresh.

I therefore seek advice as to the best method of draining the tank. I see the options as :

1) Getting a siphon kit & draining through the filler neck into a standard 5 litre container (More than 1 round trip)
2) Removing the drain plug. What sort of container would I need to catch the contents ? (Will it just flood out ??) Does the plug that's visible from the underside (next to the bolt with a penny washer on it) go directly into the tank ? Will I need sealant when I refit it ?

If I have a 1/4 of a tank left I reckon that's about 12 litres. Any advice as to the types of containers that are best suited (My local recycling centre will accept the old petrol) would be helpful. I'll be doing this at home so request the safest & least messy technique please ?

Thanks
Richard

[rgh0]

You could just top up the tank again with fresh and continue to dilute the old fuel with fresh. The ratio of old to new will be much less the second time and if it ran ok the first time it should be even better the second

You could syphon the fuel out. I would use a 20 litre metal jerry can if I did that. If you have an electric fuel pump fitted then just use that to pump out the fuel into a jerry can with a suitable hose extension fitted on the hose to the carbs

I would not try to drain 12 litres out the tank drain plug - to much free fuel like that is to big a risk

cheers
Rohan

[archigator]

I drain staight into this pan and then into a gas can(s). I then use it for lawn mower fuel. (I have two of these 5 gallon pans to take a full Elan tank, if I'm forced to.)

Gary
'71 Sprint FHC
Miami, Florida

[rcraven]

If the tank is old and the plug hasn't been undone for years and years, it might need a lot of force to undo it and may be best left untouched.

[billwill]

I use a siphon tube that has a hand bellows pump on its highest point.
And a Jerry can to transfer into.

[1964 S1]

Greetings,
I would never try to drain my fuel tank by unscrewing the drain plug. How many ways can you spell leak rust crack "small" drip?
The siphon ideas are much better. And after that process, if you open the line near the carbs and get out what's between the tank and engine, all the better... and then there's what's in the float bowls...
Which carbs do you have?
Eric

[69S4]

I just did that job two days ago - by unscrewing the drain plug. I just found a suitable container of about 5L capacity that would fit under the drain plug with enough room to get at the screw with my fingers. When the container was nearly full I put one finger over the drain hole to stop the flow and put the screw back in. The fuel came out at a rate that filled the plastic container in about one minute.

The petrol got shared out between my motorcycles and the process repeated. No problems with subsequent leaks and I was able to make some sort of assessment about dirt / rust levels in the tank (virtually none fortunately). Total amount of fuel in the tank was about 8-9L and I used a pair of the free plastic gloves you get when buying diesel to keep the fuel off my hands. No problems and the whole job took under five minutes.

[Elan45]

You can also remove the three 1/4" nuts on the bottom of the tank, the fuel line out and the filler neck and lift the tank out of the boot. Pivot the tank so the front comes up first and keep the filler neck higher. Once out, you can then poor out through the filler neck into a petrol can or directly into another cars tank or your lawn care equipment.

I wonder if it is not the fuel quality but perhaps the fuel pickup inside the tank. I have a tank that cracked a pickup tube and would not suck the last 1/4 of the tank. It stranded me beside the road once before I realized the problem.

Roger

[richardcox_lotus]

Just an update for everyone. I picked up a siphon pump & drained about 5 litres into a standard spare fuel can (The green plastic ones). I took this to my local recycling centre but they wouldn't decant it........they will only accept the fuel & keep the container ! I'm therefore trying to use up as many liquids in the house as fast as possible so I can decant the fuel into different containers !

Talk about a pain in the butt.

There is a little petrol left in the car (About an inch & a half depth) which I will siphon later when I have enough containers.

Regards
Richard

[ericbushby]

Hello Richard,
I am confused with this. When you topped up with fresh fuel the action of putting the new petrol in would have mixed it with the old petrol quite thoroughly. I don`t think the last quarter of the tankful is the same petrol that was in the tank before it was mixed. I would put the petrol which you have siphoned out into any other car you have access to ( diluted with a top up of new petrol if you wish ), fill up the Elan and try again. I don`t think it needs to be discarded.
Maybe something else is going on.
Please let us know how you get on.
Eric in Burnley
1967 S3SE DHC ( 1 degree C in the garage)

[nomad]

Unless the fuel smells like varnish rather than gasoline it will burn. I have used gasoline that was years old without a problem and as mentioned once it is diluted with new fuel you won't even know its in the tank. Really old fuel will burn with black smoke and less power till its diluted.

Kurt.

26/3754

[billwill]

It's not clear what you are trying to achieve. Getting the old fuel down to an inch and a half (about 2 litres) is plenty good enough if you put fresh fuel in on top of it. As mentioned above the old & new will mix and produce acceptable running fuel.

If what you are trying to do is completely empty the tank so that you can take it out to inspect/clean/repaint it all you need do is go buy another 5 litre green plastic can. Siphon the last of the fuel into that, do your tank maintenance, then pour it back into the tank. Take the can to a fuel station and get 5 litres of new fuel, pour that in on top of the old fuel and if you don't think that dilutes it enough, go get another fresh 5 litres and add that. That mix should be plenty good enough for you to get your MOT done etc and then you can drive to a fuel station and fill up.

Then to deal with your existing 5 litre can of old fuel, each time you go fill up the car later, take the can with you and put about 2 litres of the old fuel in the tank before you fill up with fresh fuel, the fresh fuel filling action will mix it all up nicely.

[richardcox_lotus]

Hi All

Thanks for the comments.

My initial intention was to drain the tank entirely, just to remove any hint that crap fuel is causing the crap running. Given that the car was working OK before being laid up for a period, I am loath to start investigating points/plugs/leads/coil/carb jets/floats etc, until I had at least removed the one variable of crap fuel.

The task was then complicated by the lack of decent sized containers.

However, given the recent comments I feel more confident that the small amount I have left will not be an issue once I put fresh in. There wasn't much in the way of a varnish smell BTW, more of a petrol smell !

It'll have to wait until I finish repainting the airbox (See seperate post) & re-fit that.

I'll keep you updated.

Thanks all,
Richard

[billwill]

Looking back at your original posting, I'm not at all sure that your problem is old fuel in any case.

It seems more likely to me that you may have had some dust or rust in the tank and that it is now clogging a fuel filter or obstructing one of the jets in the carburettor.

[gearbox]

I would try some injection cleaner like sea foam to see if that would clean out the build up from the fuel system. Are you folks using ethanol in your fuels yet? If so, this stuff turns into a brownish molasses substaince that will clog everything from fuel pumps to jets.