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Stale Petrol - is it a myth!!!


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19 minutes ago, Stagpowered said:

I have heard of people having problems with cars parked on steep driveways. Carb flooding when the car is parked front end down, and fuel running back to the tank when parked front end up.

Neil

A member of the Cambfollowers left the rear of his US TR6 up on ramps when he went on holiday. When he got back the garage floor was awash with oil and petrol. This was due to a dodgy diaphragm in the mechanical fuel pump

George

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  • 5 weeks later...
On 11/29/2020 at 4:21 PM, RogerH said:

Hi Folks

about five years ago I got my TR4 (The Blue Racer) mobile. It wasn't finished at the time but could be driven.

So I undertook a scientific study into stale petrol.

In 2015 I stuck a gallon of Sainsbury's best in the tank and shot off for the MOT.

The following year I stuck another gallon in and shot off for the MOT

This happened each year.

In theory there should be apprx 5 gallons of fuel in the tank minus about 20/30 miles worth of usage = 4 gallons left

Each year it took a little bit more effort to start than the previous year Last year i got  the help of an aerosol of 'Start U Bast*rd'

This year I managed to get it start by putting fresh petrol in the pump bowl and the float chambers.

After about 5 minutes running it started to cough and splutter and it died. Even with a squirt of the above miracle fluid it would not run.

 

Drastic action needed. I jacked the back of the car up and drained the tank. Apprx 2.5 gallons came out Where did the rest go !!!

What came out was quite brown and a little mirky.

I put a gallon of fresh Esso Superduperpreme 99. I refreshed the pump bowl and float chambers.  

It started after about 5 seconds and ran quite smoothly. I kept the tickover at 1000rpm and it appeared happy.

 

So my 5 year study has shown (to me at least) that petrol will go stale after a longish period. In my case with no mileage  for 364 days in each year.

I have been waiting for the TR4 60th Anniversary to get the car on the road so next year I can get the miles on her.

What would I recommend to do.

Either have very little in the tank when putting into storage. Put a gallon of 99 in when ready to start. Refresh the pump bowl and float chambers,

Or - Fill up 80-90% of tank capacity to reduce the % oxidation or whatever takes place. If it doesn't start then refresh the pump bowl and float chambers.

 

Roger

 

PS - the contact breaker gap at 0.008" didn't help

 

 

 

 

Yes storage stability is an issues with Petrol and Diesel as is bacterial corrosion, especially given  the use of biofuels  I know of one leading supermart chain who had bacterial corrosion problems in most of their tanks. I would always recommend draining petrol out if the car is not going to be used with in three months 

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Ethanol in fuel slowly oxidises to acetaldehyde and formaldehyde that will cross-link and rot many polymers, including ones that are safe in pure ethanol. Splits in the diaphragm in the PI MU may have such a cause.

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