Jumping & misfiring

[Worm]

Hi all, Just bought a 1983 air cooled 126.
But i have running problems.

Day 1: At 60mph it jumped around but a 55mph is cruised along no problem all the way back home which was 260miles!!
Day 2 Jumped around at a lower speed around 30mph drove it around and it got better but the best was 48mph any more and it would judder and lose power.

So I have tried the following.
I have removed and cleaned the electrical wires/contacts to the solenoid and electrical wires/contacts from solenoid to distributor.
I checked and made a slight adjustment to the contact gap in the distributor. Distributor cap centre carbon nib and side contacts of cap all look new, rotor arm gave a light clean.
Removed condenser and cleaned mating face to distributor.
Spark plugs removed and gaps checked, condition good.
HT lead and sparks plug leads all cleaned and tight fit.
Fuel pump head removed filter clean but removed and blew through with an air can to make sure.
Air box cover removed and wiped clean.
Breather hose from engine to air box removed and cleaned.

Took it for a test drive and got 70mph with no problems

But today took her out for a quick spin and its juddering again.

If you have any thoughts I would appreciate them. I have read the forum on similar problems and am perhaps thinking of removing the carburettor (is this an easy job will I need new seals and where will I get them from) or should I just replace the condenser on the distributor first?

Any help much appreciated, Thanks [-/

[smallcox]

Hi,

You are right in the process you have followed and yes it is difficult to test the condenser and as it is a servicable item i would first change this with the points.
 While your in the distributor check that the centrifugal wieghts are not sticking and move into advance and back again freely as this can give the symton you speak off. It is easy to blame the carb but it is an expensive part to replace, first is the fuel pump in good order and delievering enough fuel. maybe fuel lines/filter (if fitted are partically blocking)? Dont forget the small filter in the top of the carb and gauze filter in the pump.

Good luck

Steve

[Worm]

Hi,

You are right in the process you have followed and yes it is difficult to test the condenser and as it is a servicable item i would first change this with the points.
 While your in the distributor check that the centrifugal wieghts are not sticking and move into advance and back again freely as this can give the symton you speak off. It is easy to blame the carb but it is an expensive part to replace, first is the fuel pump in good order and delievering enough fuel. maybe fuel lines/filter (if fitted are partically blocking)? Dont forget the small filter in the top of the carb and gauze filter in the pump.

Good luck

Steve

Thanks for your reply, didnt know there was a filter in carb better get may Haynes manual back out. How do i confirm if the fuel pump is delivering enough fuel?

[smallcox]

Hi again,

Well you got me there, i would personnally pull the pipe off the carb and with the pipe in a glass jar have someone turm the engine over and whatch how well the feul pumps out< (you have to make this judgement yourself). No smoking while doing this job, but please stop for a cup of tea.

There is a brass bolt in the top off the carb i believe and if you remove this there is a brass filter inside, this can be done in situ.

Steve.

P.S another problem can be an air leak on the induction side, ie between the carb and cyclinder head, but try in order the points you got so far as these are easy non costly checks [-/

[Worm]

Thanks again [-/

[Worm]

Squirted some ACF50 in distributor but could not see any thing that looked like centrifugal weights, can you describe what they look like?

Went for a test drive all seemed ok for the first 4miles at 65mph then slowed down to 20mph started going up a slight hill and he jumed around again, on the flat seemed ok then another slight hill jumped again but down hill foot to the floor no problem??? Any ideas, sounds like fuel starvation rather than electrical to me if hills effect it, although on the flat the other day it did it. Still nedd to change condensor & points to see if it is these help  PS where is a good place to buy a condensor?

[smallcox]

ok,
 to check to see if the centrufugal weight are sticking in the distributor remove the distributor cap. when looking from the top view onto the distributor the shaft that the rotor arm sits on should turn 10 to 15 degress in one direction only and when you let go should return to the position you first see it in. some times the springs break and the rotor shaft moves in one direction and does not return again also the top part off the shaft rust inside the spiket it sits on (does this make sense) so no advance takes place or it sticks and intermitten advance happens like your symton.

Just another thought while i drink my tea, you may be getting one off the following being intermitten:-

1, are you getting a vacum in you petrol tank, try removing your filler cap and see if this rectifies the problem.

2, is the exhaust got large flakes of rust or silencer padding adrift and blocking the tail pipe causing poor performance, this would be noted with a very hot engine working overtime.
  
3, maybe something floating in the petrol tank moving about and particially blocking the outlet fuel pipe

but get that condenser changed as this can give all types of symtons when breaking down your local motor shop should have these sometimes in stock

[Worm]

I will try turning it to see if it springs back. Thanks [-/

When i picked the car up i know it was 30ºC outside and probably the worst weekend to pick up a car so far away but 8 miles into journey i did notice the hand brake was extremley hot! Hansnt been hot since though on my short journeys.

[Worm]

Yer seems to spring back [-/

[bis13]

have a check that the ht leads have no damage to them if they are the silicon type make sure they have no cuts or cracks in the leads and also make sure that the end fitments are in good order and that the distributor and coil have good connections the inner connection in the coil can come loose. start your car up and remove one ht lead and offer it up to the body work (i normally use the engine bay lip near the lock catch, not that it matters..) check to see if there is a good spark and then watch as you raise the regime of the engine looking for any missing or erratic spark patterns. do this on both leads, it may show up a dodgy lead or highlight that the problem is electrical. if this is fine then i would run the car and check to see that it has a steady supply of fuel with no air in the feed, have a look at the carb and have a look to see if you can see any fuel collecting in the bakerlite tray or that there is any signs of loose components as many of the problems on a 126 are often a simple adjustment or retighten. i must say that it sounds like it is the fuel pump that may be giving up as you were getting it on inclines and as it gets more tired will do the same on the flat it may not be the diaphram that is not working properly but the face where the rod pushes onto as this gets worn along with the push rod try measuring the rod travel it may be that you need to remove a shim to allow more travel of the push rod. another possibility is the coil is knackered is it getting hot?

[Worm]

Cheers for the reply, i will try the spark lead check and see if the coil is getting hot too, as soon as i get time to do it as the days just roll into one an another and before i know it another week has gone by. 

[Darrell]

I'd suspect condenser or coil.

I had a condenser problem, she ran fine at idle and low revs but when I revved it it farted and spluttered and wouldnt pick-up properly.

Then when I upgraded to the 123 ignition, it ran fine for weeks, then started to not want to idle.

Took a long time to figure out and ended-up with the cleanest carb on the planet! But replaced the coil and it all went away

If the cutting-out is a complete loss of power I'd suspect fuel but intermittent sounds electrical
I've had all of the above...and more

[Worm]

Took a long time to figure out and ended-up with the cleanest carb on the planet! But replaced the coil and it all went away

LOL how much and where is a good supplier for a coil? Cheers

[Darrell]

I've used e bay alot, chet at ricambi fiat500 seems to have alot of bits and Toto is a flamboyant Italian who can offer advice over the phone, he's worked on these engines for ages.

He's seen my car  and although he says it sounds sweet, he disagrees with my obsession to get more power out of it if I can...
Is yours an air cooled?

[Worm]

Hi again went for a drive today as i haven't been out in her for a while and the night pixies havent fixed my car as it sometimes still jumps around at various speeds. I noticed when i touched the contacts of the top of the coil when the engine is on, i get a mild zap though my fingers! Also when i touch the bodywork with my left finger then the coil terminal with the black wire i also get a mild tingling zap, is this normal? If you re feeling brave could someone confirm this is normal, before i go and buy a new coil. Much appreciated [-/