mystery running problem! 3 AA calls in 3 days!

[//no.comment]

hey, just posting to try and get this problem sorted, ive called the AA three times in 3 days! First i called and they said it needed a new coil, so i replaced the coil and still the problem was the same. Then they said it was points, so i replaced and set the points, still didint work so i called them again and after alot of head scratching, replacing the condensor and rotor arm while i was at it as i had them as spares, the final AA guy said it was time for a carb strip becasue of Cr@p from the fuel!

Answers on a postcard please!

symptoms:
The car has been running perfectly since passing its MOT a week last wednesday(first one in 20 years) absolutely flying along until friday where it mysteriously wouldnt run properly.
Couldnt hold a tickover without the throttle, it runs lumpily in first and second gears, but problem not noticeable in 3rd and 4th.
I cleaned the points on the fuel pump on friday after it cut out thinking it was a fuel issue but the symptoms are still the same. The pumps ticking nicely, i pumped a good amount of fuel into a jar
i took the plugs out and they were wet (maybe even too much fuel).
also when trying to start it with choke and throttle i managed to flood the carb.

does any one have any ideas? fuels getting into the carb and the electrics seem to be working properly( ive practically replaced it all!) so the problem must be between the float chamber and the combustion chamber right?

Thanks
Andrew

[aupickup]

wet plugs indicate the carb mixture is to rich

[//no.comment]

i wasnt sure wether the excess fuel in the combustion chambers was due to trying to start it( while using choke) and not succeeding. leaving unburnt petrol in the chamber

why would the car suddenly start running to rich? before friday it was starting first turn of the key every time.

[Simon P]

I would be inclined to suspect an electrical issue,
Have you checked to see if your getting a good spark at the plugs?
A simple test is to stick an old plug in one of the HT leads and place the plug behind a head bolt, crank the engine and see if it spark's,

Its unlikely to be fuel related in my opinion (especially if the plugs are getting wet)

[bmcecosse]

Have you set the valve gaps ? Are the spark plugs in good order - and NOT NGKs!?
But actually it sound like perfect symptoms for a flooding over float chamber - the little float valve either worn, or jammed with dirt coming through. At idle/low speed there is too much fuel, but once you get going in 3rd/4th you are using up the fuel coming through and so it runs perfectly. If you switch on the ignition - does the fuel pump tick away steadily without stopping ?
As for the AA - ask for your money back........what a waste of space they are! It's 'never' the coil If that's the best they could come up with - don't even bother to phone them in future!

[Dean]

why would the car suddenly start running to rich? before friday it was starting first turn of the key every time.

It can.. maybe the needle is loose in the dash pot and has moved a bit. Make sure it is tight and the shoulder on the needle is flush with the machined aluminium base. The mixture settings may need resetting afterwards though.

Do like suggested above though and check for a strong spark at the plugs too.

[//no.comment]

there seems to be a good spark, ive had them out and they look good.
i thought it was also an over flowing float chamber. i took the lid off and the float is free to move. not sure what more i could do :S is there any more checks i can do?

If you switch on the ignition - does the fuel pump tick away steadily without stopping ?

yes now you come to mention this i think it does, its all starting to make sense now! this would indicate the valve in the float chamber not working, right?
what can i do to fix it? can i buy a new float valve?
would this also cause over fueling? (wet plugs)
why would this suddenly have failed?

thanks for all the good answers!

[chickenjohn]

A few ideas!

check the little wire inside the distributor that runs between the points and the terminal on the distributor that goes to the coil. These connectors can fail after so many years. Also, make sure the connectors on the coil spades are OK.

Other than that, change the plug leads. Maybe you have one of the faulty rotor arms?? Another cause of poor running if the car has stood for a long time is corrosion on the distributor cap contacts inside the cap, either clean the contacts or fit a new cap.

[bmcecosse]

You can check the float valve by firstly inspecting it for any 'ridging' and secondly by holding it closed while someone switches on the ignition, or blow through it if you don't mind the petrol taste! But if the pump ticks away steadily when the engine is not running - the float valve IS the problem!

[kennatt]

The vaves are available from tom roys £8.50 very easy to replace,a sticky valve would certainly give the exact symtoms you describe,it could simple be a bit of grit under the seating take it off and clean it,be carefull you dont drop the needle they have a habit of going into a black hole sometimes simply blowing back through the system can clear it if the seating is not damaged.good luck

[10852sm]

You can check the float valve by firstly inspecting it for any 'ridging' and secondly by holding it closed while someone switches on the ignition, or blow through it if you don't mind the petrol taste! But if the pump ticks away steadily when the engine is not running - the float valve IS the problem!

Not quite my experience

When I bought my car the pump would run continuosly, ticking several times a second, engine running or not but the car would run fine, after adjusting points in the pump it ran perfectly, ticking every few seconds.

When my float sank after it cracked, the pump would run contiuosly but it was plain something was wrong in the float chamber because petrol would come out of the little breather in the top. The OP hasnt mentioned this, I cannot see how the valve can be stuck/worn/dirty without the bowl overfilling and leaking, unless the carbs are different, mine was a 1958 948cc with all original carb etc.

I would suspect something electrical still.

[//no.comment]

success....i think
i removed the dashpot lid and it ran completely fine! it was then that i remembered i put literally a couple of drops of oil into it on thursday! so i removed some oil and it now seems to be running fine (fingers crossed, i havent took it out for a spin)
it seems it may have been over damping the needle, but at high speeds where lots of air was coming in it overcame this problem and ran fine.
Though im still not hundred percent sure ive cured the problem, could this be a cure of a symptom rather than the problem?
how much oil should there be in the dashpot and what type oil should i have used?
there doesnt seem to be very much oil in the dashpot atall now. could the jet needle be sticking, and th extra damping was just too much for it to overcome?

the excess clicking from the pump i think may have been when i took the fuel pipe off the carb to check it was getting fuel. it needed re filling?

[//no.comment]

aha!
the problem is most deffinately not fixed!
i spent 2 hours waiting for the AA to come and give me a lift 800 yards back up the hill to my house! id have pushed it but its a very steep hill!
the dashpot certainly didnt have enough oil in. which means something else was wrong, i dont understand why this had momentarily fixed the problem though!
ive took the lid off the float chamber again, the valve deffinately works fine, but there is a reddish residue in the float chamber, not much, its more of a stain really. would this indicate dirt in the fuel? or rust? which would give the symptoms?
again it is driving fine when its going along, just when i stop theres no smooth power there(well no power atall really), any more ideas?
thanks for all your suggestions, hopefully together we will get to the bottom of it!
Andrew

[kennatt]

take the air filter off and lift the pison inside the carb with your finger there should be firm and steady resistance,push it up as far as you can then let go it should drop immeadiatly with a solid clunk.Do this and repost with result,plain engine oil is the usual for dashpot,and enough so that when you push the cap in there is firm resisance all the way down,if you overfill all that hapens is that the plunger pushes the excess out so its impossible to run it overfilled it self regulates,

[kittyfell]

I always use 3 in 1 in the dashpot.

[kennatt]

yes 3 in 1 oil would be ok but the recomended oil is engine oil unless running in extreme low temp then thinner oil as 3.in 1 is suggested

[xpress]

btw if you were at the bottom of the hill, could have put her in gear and cranked her up the hill with the ignition off. little tip someone gave me. secondly, the cutting out i still suspect the pump, try and swap with another one and test the spark from the ht leads. can only be insufficient sparking or fuel, electric or petrol! (or a million other things, lol).

i drove my car around the car park today and she did cut out but that's because of too much choke and she'd warmed up by then. getting there, hope you do too!!!

[kittyfell]

3 in 1 if you want the engine to pick up nicely!

[MikeHA4]

Sewing-Machine oil.... Can you still get that? Maybe vegetable oil could be the thing!

[xpress]

i use 3 in 1 for now. no problems here, better than nothing in there!