Just a query rather than a problem incase its nothing.
My 323 is very hesitant under load when its on auto choke. At higher revs its fine but at normal engine speeds it hesitates alot. It disappears when its warmed up.
I wondered if it was running too lean on choke maybe, perhaps been fiddled to get through emissions test even? Its carb btw.
It has had a new coil, plugs and leads recently.
Any ideas?
Last edited by: VxFan on Sun 18 Apr 10 at 17:04
|
My Kia's not too happy either. That's a Mazda 121 with B3 carburettered engine.
The 'fast tickover' is anything up to 3K RPM and I wondered if it had been set like that to overcome the problem. I've left well alone as there's so much electrical gubbins on the carb I don't want to disturb something I can't put back the same. It warms up so quickly it isn't a great problem.
|
Is the choke flap closing over or is it partially stuck, the higher tickover doesn't gurantee the flaps closing...you'll have to pull off the filter/pipe whatever and have a look when the engine's cold.
Otherwise give it come welly Stu.
|
|
Worth noting that the car has pretty much sat around since I bought it - I did wonder about changing the fuel filter...
|
The wonders of modern technology eh :).
|
|
If I remeber correctly, these had an electric choke. Basically a clock spring that has an electric feed from the alternator. From cold the spring winds tighter and closes the flap, as electric is applied the spring warms up a little and expands or unwinds. The steel spring in an ally housing gets a bit of corrosion and the spring cn stick to the sides, impeding its expansion and contraction. Take it off and gice it a clean up.
|
These auto chokes are quite simple to check/adjust,
just undo the screws securing the bi-metal housing and twist one way or t'other.
The choke fast idle screw looks similar to the ordinary idle speed screw.
Just remember what adjustment you make, so that you can return to that setting if need be.
There is obviously a correct procedure for setting up these critters - in the workshop manual.
|
|
Ok, new theory. I noticed today that I can smell exhaust fumes when I have the window open, but not when I have it closed, so coupled with what is actually a slightly rorty sound from the exhaust, is it fair to think it may be the manifold gasket or manifold itself? Im thinking this may be causing the uneven running aswell?
|
If the car runs ok when its warmed up, then its over-choking - check the 12v feed to the bi-metal.
Some carbs had a a vacuum operated pull down device to stop over-choking and the diaphragm could fail.
What carb is fitted to the Mazzy?
|
Having driven it 70 miles today, I would say that it runs better, but not perfectly when warmed up - esp in 2nd and 3rd under load at lower revs, like when you pull into a side road and speed up, thats when it hesitates most. Ive also noticed a tinkling noise under load aswell.
Carb is an Aisan as far as I can tell.
|
>>noticed a tinkling noise under load
Sounds like it could be pinking. Air leak into induction could cause a too lean mixture. Could be worth checking the ignition timing.
My Mazda B3 engined Kia now runs much better after changing the thermostat. It used to warm up quickly before, but the temp gauge rarely got near the middle of the scale - it does now. I know it's probably only a few degrees different and it could be psychological, but for the sake of three quid................
|
When I was in the mobile tuning game, I would always start with a compression test and end up with carb adjustment.
There are so many things that can affect running on these older cars.
Does the car 'hunt' when starting from cold (over-choke)
Always use NGK or Nippon Denso plugs.
Has the car got electronic ignition.
A weak or blocked accelerator pump jet can cause hesitancy
Tinkling noise is 'pinking' so get the ole timing light out.
You don't live anywhere near Cornwall do you stunorthants :)
|
No hunting really although it does idle very low indeed but I think thats because the cooling fan is on alot ( doesnt overheat, use water or oil or seem to have any mix of the two things ) and that brings the revs down a bit.
I wish I did live near Cornwall, but sadly Im very much stuck in the Midlands!
|
|
You could always run it over to comrade bennett and he'll shove some Redex down the carb at 3000RPM (in a quiet lane) because if its 23 year old its going to be a tad carboned up hence the pinking.
|
|
Yeah, if he offers id bow down to his superior skills with these things, Im very much an novice with carbs!
|
>>> Yeah, if he offers id bow down to his superior skills with these things <<<
Well, you could always take your bucket & chamois with thee :)
|
Right, its had a quick look over. Exhaust isnt leaking so my mech thinks it may be drawing in from a seal at the back somewhere and suggested I move the chrome exhaust trim down 4 inches to make the tail pipe further from the back of the car and try that.
Re the poor running, well it ran ok when it was there irritatingly but then it was fully warmed through. He did notice that the breather that comes out of the top of the engine was loose and needed a new seal.
He also said it is running very rich so I was wondering if this was something I could sort out? Is it just the turn of a screw or am I liable to make things much worse!? He also said bung a bottle of redex through, see if that helps too.
He reckoned it could be alot of trial and error to work out which bit was the problem as it could be fuel or electrical and any number of combinations!
|
>>> He reckoned it could be alot of trial and error to work out which bit was the problem as it could be fuel or electrical and any number of combinations! <<<
So ... he didn't have a clue then :)
I used to check the exhaust on every car I tuned by sticking my hand over it,
if it was really air tight I could actually stop the injun.
I would strongly advise you to call in a mobile tuner, then you can breathe down his neck
(after making him a cup of tea) and ask questions, see what's a'foot etc.,
Yes, you could have a Stradivarius (fiddle) with the ole mixture screw - they all used to do that (te,he,)
but - there's nuffink like knowing what you're doing, is there.
|
Well he didnt have alot of time tonight and he did put his hand over the exhaust :-)
Id favour having a fiddle myself right now to save some money, just not sure which way to turn the mixture screw! Haynes doesnt make it clear, nor does the handbook tell you.
Im going to try the redex though tomorrow as it could be fuel. It does get alot better when the car is warmed up.
|
|
Turning the mixture screw wont fix it. You need to resolve the underlying cause.
|
|
Well if a car is running rich, how would you suggest fixing that??
|
Air filter?
Auto choke? How hot does it run? Thermostat?
What do the spark plugs look like after a run?
What's it's fuel consumption?
|
|
Air filter is new, it runs at normal temp even in traffic. Economy seems a bit thirsty but not excessive, maybe 5 mpg down on what you would expect. The tail pipe is very black, plugs havent been out in 500 miles so cant comment.
|
If this is your carb stu www.carburetorfactory.com/expvw28.html it is quite a complex critter.
I haven't touched a carb for 18 years now but, it looks like No. 88 is the mixture screw, which sits behind a seal.
The idle speed screw looks like the one just above No. 84.
If you want to have a poke at it, get the injun to normal operating temp, set the idle speed to about 800 rpm, make sure item No. 10 isn't loose and that the choke flaps are fully open, prise orf the seal to the mixture screw, and screw the critter in about a 1/4 turn.
Note the idle speed, if it has increased - screw the mixture screw in another 1/4 turn (and so on etc.)
When you get to a point where the idle speed starts to decrease, back off the mixture screw about a 1/4 of a turn and refit the seal (not essential)
You may well be lucky comrade stu but there are any gaskets & diaphragms that can fail on this particular carb - Good Luck!
|
well the black tailpipe indicates rich ok. If its rich it needs more air. Is the choke flap returning ok, is the crankcase and other breathers blocked? how well does it start?
you need to hoike the plugs out to check the colour of them .
|
Perro.
Would that be an idle mixture screw? I believe this is a fixed jet carb and the running mixture would be controlled by the main jets.
I'm thinking it would be more to do with the choke/water temperature.
|
>>> Would that be an idle mixture screw? <<<
I dunno looseat - its been a long time you see ... ave vous got that carb on your Pride?
|
It looks similar to mine, but with less gubbins. My pride's got a cat!
Down boy!
|
Im going to have a tinker later, thanks guys, ill have a poke about.
Re starting, the autochoke works very well - quick squeeze on the throttle and turn the key, when you want it off, just blip the throttle and it goes off. When the car is hot it wont start with just the key, but it you give it a bit of gas aswell it fires up very quickly. It does idle low, nearly cutting out but it never actually stops.
|
|
I have the same problem. Easy start up. When its running fast its okay but when it is slow it's not.
|
|
I wonder if Stu sold his little Mazda to Brandon?
|
Mazda 323 - 87 1.3 Poor running on choke - bathtub tom
