12 replies to this topic

[d46blackledge]

Hi all. 

 

I am fairly new to the forum and this is my first ever post, apologies if this is done incorrectly. I have an unusual issue that I cannot find the answer to after hours of searching online... 

 

I have a 1986 Mini, running a 1275cc A+ engine with twin HS2 carbs, AAC needles. The crazy story is: my car will not start. 

 

Back story: I was using the mini daily and it was working fine, although admittedly running a tad rich. One day whilst driving home from the MOT center, my mini just died (luckily whilst pulling up on the drive!). It sounded like it had just ran out of fuel. Since then I have never been able to get it started. The garage had just swapped the points, condenser and coil as the same thing happened to them on a test drive. Despite this, the issue came back after just 50 mins of driving. After thinking it could be ignition related, I converted the car to AccuSpark electronic ignition. No reward. 

 

Checks I have done:

- Added more fuel 

- I have spark. 

- I have compression: between 190-215 psi on all cylinders.

- I have fuel going into the carbs, there is plenty in the float chambers.

- Timing seemed fine before the car stopped. I do now have a timing light to check when it gets going  

- Leads, plugs, coil are new or in good condition.

- Battery & starter motor are strong.

 

When I pour a little fuel into the air intake, I get life! For this reason, I assumed the issue was carb related. I inspected the carbs, cleaned the jets and chambers, everything looked good. I could not see a reason why they were not working. I anyway decided to buy a rebuild kit from Mini spares and replace all necessary parts, including jets and whole new float chamber assemblies. I cleaned everything in the ultrasonic cleaner we have at work. I adjusted the carbs as the manual suggested. Still no reward. 

 

When ticking over fuel goes into the float chambers, but does not seem to get sucked through the jet into the inlet on either carb. I do not think I have a leak in the manifold, but I guess there is not enough vacuum in the chamber to suck the fuel in?

 

I am baffled! 

 

If anyone has had a similar issue or can offer advice, it would very much be appreciated!! 

 

Thanks in advance,

 

Dan 

Edited by d46blackledge, 31 January 2022 - 02:01 PM.

[yeti21586]

Morning, is fuel leaving the float chamber and actually getting into the carb? blocked jet etc?

[sonscar]

Take the dashpots off and look down into the jets and you should see fuel.If it is dry the jet tube has a washer where it connects to the float chamber which can get mushy.If fuel is there I would suspect the manifold gasket.Almost all minis will fail to proceed at some point.Have fun,Steve..

[d46blackledge]

Morning, is fuel leaving the float chamber and actually getting into the carb? blocked jet etc?

Morning Chris!

 

I don't believe fuel is leaving the float chamber, but I do know the jets aren't blocked. I cleaned the old ones, and then swapped them for new. Neither option worked 

 

 

 

Take the dashpots off and look down into the jets and you should see fuel.If it is dry the jet tube has a washer where it connects to the float chamber which can get mushy.If fuel is there I would suspect the manifold gasket.Almost all minis will fail to proceed at some point.Have fun,Steve..

 

Morning Steve, thanks for your reply. I do not see fuel when looking down into the jet so it is indeed dry. The washers did not appear mushy when I removed the old ones, however I do have a manifold gasket I can put on as precaution.

[sonscar]

The fuel should be visible in the jet at the same level as in the float chamber.Steve..

[Steam]

Using a short length of fuel hose press one end down onto the jet and gently blow through the hose. this will prove if they are blocked or not.

it is not uncommon for the small o ring to get out of place and block the connection at the bowl to pipe.

[d46blackledge]

Thanks Steve and Dave. I will have another go tonight after work 

[coopertaz]

disconnect coil and remove air filter assy. put palm of hand over one carb and crank engine with throttle depressed (you need 2 people!), you will feel suction if manifold drawing, repeat for other. if you have no suction then manifold leak. you will aslo have some fuel on plam after this. if manifold suction ok are plugs wet after cranking. if both these are ok look at ignition circuit but need to seperate issue.

Edited by coopertaz, 01 February 2022 - 10:40 AM.

[coopertaz]

also are needle pistons free to move in dashpots and oil level correct

[bpirie1000]

Have you looked at the inner part of the dash pot.

Make sure it is not fouling on the inner wherw the needle goes. If this sticks the needle will not allow any fuel through into the combustion chamber.

I trust you have good compression.

Does the car still come to life when you pour fresh fuel into the carb elbow on the air filter side?

[d46blackledge]

Have you looked at the inner part of the dash pot.

Make sure it is not fouling on the inner wherw the needle goes. If this sticks the needle will not allow any fuel through into the combustion chamber.

I trust you have good compression.

Does the car still come to life when you pour fresh fuel into the carb elbow on the air filter side?

 

Thanks for your reply, during the carb rebuilt I cleaned all components in an ultrasonic before reassembly. The dashpot is clean and with oil. The needle piston is able to freely move up and down.

 

As I mentioned before: compression I have 190-215 psi across the cylinders and indeed when I pour fresh fuel into the carb elbow I do get some life.

 

 

disconnect coil and remove air filter assy. put palm of hand over one carb and crank engine with throttle depressed (you need 2 people!), you will feel suction if manifold drawing, repeat for other. if you have no suction then manifold leak. you will aslo have some fuel on plam after this. if manifold suction ok are plugs wet after cranking. if both these are ok look at ignition circuit but need to seperate issue.

 

 

Thanks coopertaz, I did try this with a friend of mine, however with a slightly different method to what you say, I will try this again tonight.

[d46blackledge]

Thanks for your help chaps. To update:

 

 

Using a short length of fuel hose press one end down onto the jet and gently blow through the hose. this will prove if they are blocked or not.

it is not uncommon for the small o ring to get out of place and block the connection at the bowl to pipe.

 

I did as you said Dave, the right carb is very easy to blow through, requires no effort. The left carb however is completely blocked. When rebuilding the carbs and replacing the jets, I remember the jet from the left carb being very tricky to remove, and the new one was very difficult to screw in again. Now this was my first carb rebuild so, knowing the washers etc on the end of the jet I just assumed it was like this to prevent fuel leakage. When rebuilding the right carb however, it was MUCH easier to replace the jets in the float chamber end.

 

After this I did what Coopertaz mentioned:

 

disconnect coil and remove air filter assy. put palm of hand over one carb and crank engine with throttle depressed (you need 2 people!), you will feel suction if manifold drawing, repeat for other. if you have no suction then manifold leak. you will aslo have some fuel on plam after this. if manifold suction ok are plugs wet after cranking. if both these are ok look at ignition circuit but need to seperate issue.

 

From both chambers I had a little suction, however no fuel on my palm. 

 

To check if the blocked jet (probably due to my poor application) on the left carb alone was the issue, I was pouring a little fuel into that inlet; leaving the right carb to operate as normal, whilst a friend of mine turned the ignition. It fired up and ran briefly!! I am still surprised that there was no life from the seemingly ok right carb.

 

Tonight I will strip the left carb and check the location of the O ring. If I can find some for sale, I may try to replace the float chamber itself and jet incase of damage. 

[maccers]

I have this type of issue on a single HS4 - ordered new jet assembly, cleaned the carb float bowl but as said above the rubber seal at the bottom exist of the bowl where the small link pipe that connects the jet is all broken down and will need cleared out with a tooth pick or something soft before I install the new one with new rubber sealing washer.