9 replies to this topic

[soppa]

Hello,

I'm new Morris Mini owner and i'm from Finland. First, sorry about my bad english. I have little problem with my engine. Engine start well but when I press down it's starts misfire and cracks. I clean the distributor but that wasn't the problem. What i must do next? I haven't change plugs, that maybe helps but i don't believe the problem came from those. Please, explain well because i don't understand slang words.

And the engine is 12HI59a

yours sincerely,

Marko

[Pavel]

Hi

Firstly welcome to the forum!

Did your engine run OK before? Did it suddenly start misfiring? Or was it like that since you bought the car. I would definitely check the fuel mixture (if you just brought your car over to finland from elsewhere, because of the temperature difference your fuel settings will be wrong).
I would also change the following anyway since you'll have to change them in the future when servicing anyway:
Distributor cap
Condenser
Points
Rotor Arm
Plug Leads
Spark Plugs

That should ensure that your ignition is in good order. After that the only thing left is to set up the carburettor as I said before because your mixture may be all wrong.

Good luck!

[Jammy]

Follow what Pavel has said, only change things one at a time, then you know what was causing the problem!

[soppa]

Hi

Firstly welcome to the forum!

Did your engine run OK before? Did it suddenly start misfiring? Or was it like that since you bought the car. I would definitely check the fuel mixture (if you just brought your car over to finland from elsewhere, because of the temperature difference your fuel settings will be wrong).
I would also change the following anyway since you'll have to change them in the future when servicing anyway:
Distributor cap
Condenser
Points
Rotor Arm
Plug Leads
Spark Plugs

That should ensure that your ignition is in good order. After that the only thing left is to set up the carburettor as I said before because your mixture may be all wrong.

Good luck!

Thanks Pavel,


I have just bought the car and old owner said to me that engine start to misfire when he pick up car on winter storage. I also ask this problem to finnish forum and they said just about same things what you said. Engine run always OK to tick over but when pressing down it's starts misfiring. Rotation speed meter seems in this moment about 2000-> rpm. Does the fuel pump must be upright? My pump is horizontal... pump is also electric. Is it posible that pump is attracting dirt in to the filter?? and that is maybe the reason to misfiring?? If i turn pump to right direction and clean the filter and problem seems to continue, i change next those things what you enumerate.

[pikey7]

what year is your car? Is it the carburettor or injection version?

[Tom Sanderson]

it sounds like the carb needs cleaning out.

that is if its not a fuel injection car like pikey7 says.

oh, and welcome to the forum.

[dklawson]

Since you say the car is badged as a "Morris" I'm assuming the car is old enough to have a carburetor. When you say the car misfires and cracks, do you mean that the car runs well at idle but develops problems and backfires as the engine speed is increase? If so, is the backfire through the exhaust or through back up through the carburetor (do you hear the backfire from the exhaust or does it come from the engine compartment)? If the backfire is through the exhaust, go through the ignition system as suggested above, changing components one at a time. Since Minis are new to you, remember the firing order is 1-3-4-2 counterclockwise as you look at the top of the distributor and #1 cylinder being close to the water pump.

If the backfire appears to be coming from the engine compartment, it is likely to be fuel starvation. This can be from plugged filters, an old-tired fuel pump, or problems with the float valves in the carburetor itself. The factory electric pump on carburetor equipped cars were mounted horizontally on the rear suspension sub frame.

Before you get too involved in troubleshooting the problem, be sure to locate a manual for your Mini as it will have drawings and step-by-step instructions on how to adjust the ignition and fuel system.

[soppa]

Since you say the car is badged as a "Morris" I'm assuming the car is old enough to have a carburetor. When you say the car misfires and cracks, do you mean that the car runs well at idle but develops problems and backfires as the engine speed is increase? If so, is the backfire through the exhaust or through back up through the carburetor (do you hear the backfire from the exhaust or does it come from the engine compartment)? If the backfire is through the exhaust, go through the ignition system as suggested above, changing components one at a time. Since Minis are new to you, remember the firing order is 1-3-4-2 counterclockwise as you look at the top of the distributor and #1 cylinder being close to the water pump.

If the backfire appears to be coming from the engine compartment, it is likely to be fuel starvation. This can be from plugged filters, an old-tired fuel pump, or problems with the float valves in the carburetor itself. The factory electric pump on carburetor equipped cars were mounted horizontally on the rear suspension sub frame.

Before you get too involved in troubleshooting the problem, be sure to locate a manual for your Mini as it will have drawings and step-by-step instructions on how to adjust the ignition and fuel system.

My car is 1969 and I assume that body is 1969 but I don't think that engine is same vintage. But there are carburettor and I assume that's working fine... Yesterday I clean the fuelpump and check up carburettor. Fuel come pressure to the carburettor but I don't know are the pressure enough.
I meen that engine work fine by idle but when depress it's starts misfire. I hear the backfire from the exhaust and from engine. Yesterday I also order new coil, distributor cap, distributor rotor, condenser, points and spark plugs.

Maybe today or tomorrow parts come and if those are solution to my problem....

By the way, someone said that my engine is Metro....?

[syholl]

If the car has just come out of winter storage, has the petrol been sat in the tank for a long time...? Petrol goes off very quickly, within weeks it starts to lose its performance, and after being stored for months and months it really needs replacing. Old petrol can leave a nasty residue inside your carburettor and in the fuel lines etc.

Definitely worth draining the tank and refilling with new stuff.

[dklawson]

The nominal fuel pressure to the carburetor should be about 2-3 psi [0.14-0.2 bar]. Pressure reaching the carburetor is only part of the issue. If the float valve is stuck (in the carburetor's float bowl) or if the carburetor jet is partially blocked you will get lean condition backfires through the carburetor.

If you are hearing more backfires through the exhaust, focus your initial attention on the ignition system.

Go back to Pavel's post where he gave you a list of things to replace. Buy them all and install them one at a time, testing the engine after each change. Don't change everything at once. As mentioned earlier, if you don't have a manual for the car you should get one before getting too involved in troubleshooting.