Draining fuel

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Not_Anumber
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Draining fuel

Post by Not_Anumber » Tue Dec 08, 2020 3:40 pm

To try and keep up my enthusiasm on working on the car in these temperatures it would be good to get the engine started. I remember it started and ran when I first refitted the engine after tidying the engine bay but that was a few years ago now.

What is the consensus on draining old fuel. Is it worth doing after the car has been standing a few years ?

if so, is there a preferred way of draining the tank please ?

Dave Wheatley
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Re: Draining fuel

Post by Dave Wheatley » Wed Dec 09, 2020 1:20 pm

Some people will say that modern petrol is no good after it has stood for 2 months. My Austin 7 started easily enough recently after a year standing, so it's anybody's guess, but a few years is too long!
I would have thought that the easiest way to drain the tank would be to disconnect the fuel pipe at the carbs and let the fuel pump empty it into a can.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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Charles Farran
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Re: Draining fuel

Post by Charles Farran » Wed Dec 09, 2020 2:12 pm

I would agree with David, however you may wish to leave a small amount in the tank rather than potentially dredge up any dubious contents at the bottom & block the pump. You could then add 2 or 3 gallons of fresh at the top - that's what i would do.
You may find ,as you do so, that the rubber pipes from the tank to the pump & then to the steel / copper pipe that runs to the front leak fuel due to their age unless you have recently changed them. Good luck with starting the engine - let us know how you get on.
Cheers
Charles
1980 Roadster

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Tom Brearley
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Re: Draining fuel

Post by Tom Brearley » Wed Dec 09, 2020 9:02 pm

Moss have a video all about starting up a dormant engine: https://www.youtube.com/watch?v=Kx8ysblT7WY

My engine sat for 3 years while the car was being (lovingly*) restored. When I came to re-start she fired up but then bogged down after a few seconds and died. The cause was white gunge in the float bowls left behind by evaporated petrol. Once that was cleaned out, she was back to her normal tappety self. A great sound.



* slowly
1973 MGB GT
Mallard Green / Autumn Leaf

Vic Butler
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Re: Draining fuel

Post by Vic Butler » Thu Dec 10, 2020 7:01 pm

Dave Wheatley wrote:
Wed Dec 09, 2020 1:20 pm
Some people will say that modern petrol is no good after it has stood for 2 months. My Austin 7 started easily enough recently after a year standing, so it's anybody's guess, but a few years is too long!
I would have thought that the easiest way to drain the tank would be to disconnect the fuel pipe at the carbs and let the fuel pump empty it into a can.
Surely the pump isn't designed to run continuously for long periods.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine

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Peter Cresswell
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Re: Draining fuel

Post by Peter Cresswell » Thu Dec 10, 2020 9:25 pm

I would add to the above - before draining the fuel, decide how you are going to get rid of it. I drained off about 5 gallons of stale fuel a few years ago (when I was working on my Mini Cooper) and then found it very difficult to get rid of the stuff. Eventually a friend took it and poured it into his grey Fergie! I did find out that local Fire Stations might take fuel for practicing putting out fuel fires, but other than that it was a problem I hadn't thought about.

You have intimated your car has been off the road for some considerable time, so (unless you know the fuel components have been replaced recently) I would suggest you change all the fuel lines (metal and flexible) and overhaul or replace the fuel pump as the kits and pumps are now ethanol proof and the same with the carbs. Fuel fires are frequently publicised in the classic car press, and the cause is most likely old steel fuel lines and rotten hoses. Ethanol has been around long enough for it to have started to rot away these components.
Pete
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965

Dave Wheatley
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Re: Draining fuel

Post by Dave Wheatley » Fri Dec 11, 2020 9:29 am

Vic Butler wrote:
Thu Dec 10, 2020 7:01 pm
Dave Wheatley wrote:
Wed Dec 09, 2020 1:20 pm
Some people will say that modern petrol is no good after it has stood for 2 months. My Austin 7 started easily enough recently after a year standing, so it's anybody's guess, but a few years is too long!
I would have thought that the easiest way to drain the tank would be to disconnect the fuel pipe at the carbs and let the fuel pump empty it into a can.
Surely the pump isn't designed to run continuously for long periods.
Interesting point Vic. I don't know the answer to that. I don't even know the gallons per hour rate of the pump, but I wouldn't worry about it myself after considering the alternatives.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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Charles Farran
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Re: Draining fuel

Post by Charles Farran » Fri Dec 11, 2020 1:35 pm

I can't think it's an issue as long as fuel is passing through the pump. 3 years on the trot i drove from Le Havre to Menton via the auto routes stopping only twice for petrol & an hour lunch break with my foot to the floor in the 1980s apart from round Paris - about 11 hours of constant driving & the pump never played up & is still on the car today.
Cheers, Charles
1980 Roadster

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Tom Brearley
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Re: Draining fuel

Post by Tom Brearley » Fri Dec 11, 2020 5:41 pm

I don't even know the gallons per hour rate of the pump, but I wouldn't worry about it myself after considering the alternatives.
I've had points and solid-state SU pumps and both have delivered 1.25 pints in 30 secs when in good fettle.

Firms who remedy 'misfuelling' (putting petrol in a diesel car or vice versa) are able to come to your house to dispose of fuel.
1973 MGB GT
Mallard Green / Autumn Leaf

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Bumpa
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Re: Draining fuel

Post by Bumpa » Mon Dec 14, 2020 12:09 pm

To get rid of the old fuel, I would put a half gallon into another car after it has been filled with fresh stuff. It will get used up. I put the old fuel from my project MGB into my daily use Triumph Dolomite with no ill effects - the fuel was about 5 years old. My MGB's tank has a drain plug which made the job very easy.

I've never understood the idea that if you let the fuel level get low, the grot in the bottom of the tank will get picked up. The fuel pick-up in the tank is right at the bottom anyway, so why doesn't it get picked up with a half full tank, or any other amount?
Mike
1969 MGB GTV8 3.9 Conversion, 1977 Triumph Dolomite 1850HL, 1971 MGB roadster undergoing restoration.

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