20 replies to this topic

[mbolt998]

My car (1979 Mini 1000, completely standard, single carb, mechanical fuel pump on the block) starts at once if you drove it a day or two previously. But if you leave it for a week or two it needs a little bit of extra cranking to get some fuel up to the carb.

 

My questions are: is this normal? Is the problem fuel evaporating out of the float chamber? Is it worth my looking at the gasket on that? Or is air maybe getting into the fuel line?

[Ethel]

Could be, wouldn't have though it'd make that much difference at this time of year though. Could be worth checking the jet union to the float chamber shows no signs of weeping, but I think it's more likely it just takes a bit longer to catch because the fuel won't vaporise as easily in the cold and the battery will be a bit more run down.  

[weef]

  By a few extra cranks what do you mean?. If it takes say cranking in short bursts five minutes to start then maybe something is wrong, but if it is only having to crank three or four short bursts before the engine starts then I would say it is OK.

Do not expect your Mini to be an on the button starter as todays modern cars are, even if they have been sitting for a few days, but when used regularly your Mini should be an on the button starter like a modern car.

If when in regular use your car starts and performs as expected then I would not be too concerned, but if it does take a few turns to start it may be worth while checking. 

[mbolt998]

  By a few extra cranks what do you mean?. If it takes say cranking in short bursts five minutes to start then maybe something is wrong, but if it is only having to crank three or four short bursts before the engine starts then I would say it is OK.

Do not expect your Mini to be an on the button starter as todays modern cars are, even if they have been sitting for a few days, but when used regularly your Mini should be an on the button starter like a modern car.

If when in regular use your car starts and performs as expected then I would not be too concerned, but if it does take a few turns to start it may be worth while checking. 

Not 5m. Maybe up to 30s or so in a few bursts (I don't just crank it continuously).

[weef]

If it starts up as you described and runs fine once started I would say that this is quite acceptable.

[Steam]

It is probably a normal situation. If you wanted to find out why there are a number of things to try but it is not a fault as such.
The fuel is probably evaporating from the jet tube so if you were to dribble a small amount of fuel into the carb through the air imtake it will probably fire straight up.

[mbolt998]

Thanks for all the pointers everyone. I'm going to file this one under "not broke so don't fix it".

[68+86auto]

I wouldn't worry. It could even be a marginal battery.

[mbolt998]

I wouldn't worry. It could even be a marginal battery.

The battery should be pretty OK. It's only 2 or 3y old.

[stuart bowes]

age is one factor but how many times has it been left to run flat and needed a proper recharge, they don't like that much, keep them trickle charged, a decent little solar charger can help, or use a proper cutoff switch to avoid drain

 

also what brand is it, some don't last as well as others especially if you get budget from ECP for example (speaking from 1st hand experience!)  shouldn't go too far wrong with good names like Bosch / Varta or Yuasa

 

just general notes about batteries whilst on topic, your particular one may well be fine

Edited by stuart bowes, 17 December 2023 - 07:11 PM.

[68+86auto]

 

I wouldn't worry. It could even be a marginal battery.

The battery should be pretty OK. It's only 2 or 3y old.

 

 

It should be fine but it might not be. A quick test is to disable the ignition system and measure the voltage at the battery whilst cranking. under 9.6v is bad.

Since it is starting I wouldn't worry much yet. If however it reads under 9.6v then you need to think seriously about replacing the battery.


There is a good chance your mini is just functioning normally.

Edited by 68+86auto, 17 December 2023 - 10:27 PM.

[mbolt998]

The battery is a Halfords one. The car needed a bit of work over about a couple of years before I drove it, but I ran it a few times, but also charged the battery up with a charger every couple of weeks or so. I think it's in pretty decent shape. But yes if the battery is a bit knackered you won't get a strong spark after all that cranking. But I'm pretty sure it's just pumping fuel that's taking the time because when it does get there it fires easily.

[stuart bowes]

is this a +1 score for electric fuel pumps then (or will that not make much difference)

 

it's just I'm thinking, the electric pump should provide full pressure (almost) straight away whereas the mechanical pump relies on a few spins of the engine to get up to pressure.  made worse if left a while and gravity has pulled the fuel back down the line ? is that a thing

 

is there some good reason a 1 way valve can't be used to keep the fuel up at the top (a bit like the old finger over the end of a straw to hold a liquid)  just spitballing ideas I have no 1st hand experience 

 

would be interested though because at this point I'm also thinking do I stick with mechanical or go for electric

Edited by stuart bowes, 18 December 2023 - 09:43 AM.

[Lplus]

Mechanical fuel pumps have one way valves on both entry and exit, if they didn't they wouldn't work.  The seals  could be failing, but even then fuel should remain in the float bowl - and the fact the engine starts easily after a day suggests it does at least in the short term. Evaporation over time sounds the most likely culprit.

[stuart bowes]

ah thanks so in this respect electrical pump doesn't offer an advantage over mechanical then (assuming all seals in good condition) ?