MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Trouble starting but runs well

I have been without my car for a few months but collected it today. The battery was very good, turning the engine without any problem, but it took quite a while to catch and start. Once it started, it ran well. And it was easy to start again after stopping.
It has been like this all year, and based on earlier experiences, if I try to start it tomorrow, even though it now will be cold, it will probably start first time, without a problem (but I will double check tomorrow). It seems that I only have the problem if I leave the car parked up for a couple of weeks or more. Almost as if something very gradually gets damp through condensation but drys out once it eventually starts.
Any idea if this is likely to be a fuel or electrics issue? I have electronic ignition but otherwise everything is standard.
I know some will say the answer is simple, just use the car more regularly, but I would like to sort it out regardless but am not sure where to start looking.
Graham V

I think it's the modern fuel and the petrol remaining in the carb bowls goes off very quickly. I find much the same when I don't use the car for a couple of weeks. I anticipate it now and drop a teaspoon of fresh fuel from my can onto each filter canister. Starts first pull.

Steve
Steve Gyles

Thanks Steve. Interesting theory.
As I predicted, even though I had the problem yesterday, it fired up first time today.
But why would the petrol in the carb bowl go off quicker than the fuel in the tank? Other thing is that as I mentioned, it only happens when the car has been unused for several weeks. So when I go to start it, the fuel pump clicks away for a while to fill the bowl, so unlikely to have been much fuel in there beforehand.
Hmmm?
Graham V

Graham. A few tablespoons in the bowls compared to say 50 litres in the tank. I think the small quantity will lose its properties first especially in the hot ambient engine compartment temperature when you last shut down.

If you watch Bangers and Cash you will see them carrying 'Quick Start' aerosols around with them all the time. I think the starting issues with current fuels is very commonplace.

Steve
Steve Gyles

Thanks Steve. I appreciate your input and bow to your better knowledge. But I do find it hard to get my head round it, if the empty bowls have been refilled from the tank.
Annoyingly it's difficult to diagnose, bearing in mind that once the car starts, I can't test it again until I have left it sleep for a few weeks.

Those quick start aeresols are very effective. And you are right that if it makes mine fire up immediately, it would prove it is a fuel issue, and not the electrics.
That would fit another theory - as I was guessing it is an electrics problem; the coil maybe. And the golden rule says that if you think its the electrics, it will be the fuel, and vice versa!

I do buy ethanol free petrol, but I assume its not just about ethanol.
Graham V

Graham

I am not suggesting the bowls are empty. Just some of the constituent burny stuff has evaporated such as the ethylene? I guess the first few sucks from the engine takes in the less volatile liquid and by the time the better stuff is sucked in the engine is flooded with rubbish.

Steve
Steve Gyles

Graham
I have exactly the same problem. These days, I don't even bother to try and start it without "Easystart" as it just puts extra drain on the battery, I can thoroughly recommend it.
But do try to avoid doing what I did a couple of months ago - I inadvertently picked up a can of white spray paint instead of the Easystart ... needless to say it didn't start first time on that occasion!
Eddy
E Maher

Have you optimised your choke setting to provide a richer mixture to facilitate a cold start?
Bolney Coupe

Steve and Eddy,
Reassuring that you both have the same problem - and recommend the same solution. I have the original style air filters with fairly thick filtering felt. I am not sure if the aerosol will work through that but I will give it a go.

David (Bolney).
If it was down to the choke, I’m not sure that would explain how it starts absolutely fine, the day after I have run the engine. The problem is only there when the car has sat unused for a few weeks.
Graham V

Check that when you pull the choke that both jets move down about 6mm. You need a mirror to see this! MGA needs a richer mixture to start when cold.
Read mgaguru section
http://www.mgaguru.com/mgtech/carbs/cb102.htm
Cheers
Mike
Mike Ellsmore

Graham. Have you used fuel stabilizer in the fuel you are using? Do not know about what is available in the UK, but fuels available in the US often start to break down within a week of purchase. For the vehicles that are driven less regularly, many of us add fuel stabilizer to the tank to prevent the type of problem you are describing. As a test, a few ounces (75 ml?) of fuel put into a small glass jar, lightly sealed, and left outside for a week is a good test of the chance that your gas (petrol) is breaking down. I find the smell of the fuel, after a week outside, is very different than when it is originally pumped at the gas station. Fuel stabilizer has worked for me over quite a number of years in helping to reduce fuel oxidation. And, since you note that the fuel pump seems to have to pump the float bowls full each time you start the car, there is a good chance that evaporation and oxidation play a significant role in what is happening with your situation.

Les
Les Bengtson

Good advice but Quick start aerosols are not the answer if the air filters are fitted and are not needed if the choke is working as it should. These engines do need a rich mixture to start from cold - i.e. full choke. If that doesn't work, suspect stale fuel. Autumn and low mileage ahead - a fuel preservative is worth considering.
Roger Walker

Thank you everyone for all the helpful input. I now have plenty to think about and work on.
Sadly because we moved home very recently I have very little time on my hands for tinkering, but will do so as soon as I have some spare time.
And I will report back when I have tinkered!
Graham V

This thread was discussed between 08/09/2023 and 13/09/2023

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.