misfire

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jon123

jon123

Member
Posts
68
just bought a 2.25 pet with a newish weber, idles fine and runs ok for 20-25 minutes then misfires really badly. if you repeatibly blip the accelerator quickey you can make it stall. Misses badly under loader. Have Kenlowe set on normal should i run cooler? Any ideas? Landy has been used much for a few years.
 
Once again, this may be carburettor ICING.

Where is the air inlet for the carb?

In a petrol engine the inlet air should be taken from a WARM area to try to reduce the risk of carb icing.

CharlesY
 
charles.
a k&n is fitted so no the inlet air isnt from a warm area. The problem is after 20 minute driving the misfire starts, including popping/backfiring when under load. Then if it dies you have to leave is a few minutes but i dont think its flooding so i suppose icing is a possibility. It will then idle perfectly but misfire agian under load through about 3000 - 4000 rpm. The weber and filter look new and i have seen loads of landys with this mod on 2.25 petrol so i am a bit baffled. Excuse the grammer in my first post what i meant to say is that the landy hasnt been used for several years.
Can you suggest anything i can try.
 
OK ..... stage one is to take the air filter off.
Run around for a while with it off.

Weber carbs are VERY sensitive to depression (partial vacuum) in the pipes above them, and it causes huge amounts of fuel to get sucked in.

Icing inside these carbs is practically a certainty in wintry weather unless you arrange a heated inlet air system.

CharlesY
 
welditup said:
hi you want to dump the webber they are pain in the arse and fit a zenith ?
Click to expand...

ill agree with that! my webber was no end of bother, i had to clean it every week, and my landy never ran right with it on, it seemed very flat.

zenith all the way imo.
 
my uncle had k&n filters on his 2.25 petrol dont use them unless you have tweaked with the performance also k&n filters absorb condensation i have a original if you need it £10.00 newish that all do it but thats what my uncle said and when he changed it for the original it workd fine also whilst your there try new s.plugs and gaskets
 
series 3 sweet 16 said:
my uncle had k&n filters on his 2.25 petrol dont use them unless you have tweaked with the performance also k&n filters absorb condensation i have a original if you need it £10.00 newish that all do it but thats what my uncle said and when he changed it for the original it workd fine also whilst your there try new s.plugs and gaskets
Click to expand...
****! what age do they teach punctuation these daze?
 
maybe his comma key is RIP

or seeing as he's only 16 he might not have done punctuation yet seeing as it's deemed to be a bit complex fer their little eds
 
Charles
Sorry to keep asking you more ques. I got the clutch fixed last night and ran round for 20 mins without K&N it seemed better but perhpas i didnt test it long enough. Anyway assuming it does run better this way what do you think i should do long term. Should i ditch the Weber like some suggest or can i get a better air inlet system for it that will take warm air from the manifold area? Surely Webers can run well on 2.25, i thought from what i read that they are a good upgrade.
 
I have a 34IHC Weber and a K+N filter on my 2.25 and i have only had a idle problem (Sorted out by adjusting the mixture).
I would recon that you may have **** in the fuel (Rusty tank) or water.
also look for a air leak.
I have only suffered Icing on a cold foggy day after doing ramming speed for 20mins or so.
Weber's and K+N do work if set up right.
 
jon123 said:
Charles
Sorry to keep asking you more ques. I got the clutch fixed last night and ran round for 20 mins without K&N it seemed better but perhpas i didnt test it long enough. Anyway assuming it does run better this way what do you think i should do long term. Should i ditch the Weber like some suggest or can i get a better air inlet system for it that will take warm air from the manifold area? Surely Webers can run well on 2.25, i thought from what i read that they are a good upgrade.
Click to expand...

I say keep the Weber for sure.
These are good carbs, and you should get the car running well on it.

However, because of their venturi design, they do freeze up smartish, and not eanough warmth comes up from the manifold to stop that. It needs to draw warm air, and if I were you I would go for the plan of taking air warmed at the manifolds. ALL older cars used to do this as a matter of routine.

The ice that forms is not from the fuel - it is water vapour in the air freezing out due to the temperature drop at the venturi inside the carb. Warmed air will stop it.

Charles.
 
i am still struggling with this, runs a bit better with the k&n off but still a problem. starts in this weather with almost no choke and is smokey but cant seem to lean the mixture up on the screw at the base of the weber.
any one???

jon
 
I had a Suzuki SJ that I put a SU carb onto, it would do the same thing that you are saying poor performance and icing up and this was during the summer. I got some copper brake pipe and tapped into the hot water from the heater and put a couple of coils around the Carb adapter plate on the inlet manifold. Worked fine after that.
 
Almost certainly icing, fiddle around with the heater hoses,strap the petrol pipe to one of tham. Mine did it occasionally , but the good economy made it worth while.
 
Long term solution is to duct warmed air off the exhaust manifold into the first air inlet. There really isn't any other practical long term solution.

CharlesY
 
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