Timing a series 3 - Help needed plzzz

bowers1986 · Oct 2, 2009

CharlesY said:
That is the classic descripion of the Carb ACCELERATOR PUMP not working.

When you open the throttle the very light AIR rushes in immediately but the relatively heavy PETROL lags way behind the air, and the mixture becomes so lean the engine goes as flat as a pancake. It may backfire into the carb, which can start an engine fire. If you open the throttle very slowly and gently it may pick up speed quite well.

Open up the air system till you can look right down into the carburettor venturi.
While peering in, open the throttle wide open and hold it open. You should see a jet of fuel like out of a water-pistol being sprayed dowwards into the manifold, and this should last several seconds.

If there is no jet of fuel, the accelerator pump isn't working. Fix it.

CharlesY

Thanks for the response charlesY much appreciated, Am I right in assuming the accelerator pump is part of the carburetor? The carb currently fitted is a Webber 34ICH. Dont suppose anyone knows if there is a diagram available any where on the net, as my manual only shows the zenith and solex carburetors. Also would the problem you mentioned above cause the engine to run hot,,because the mixtures lean or is that another problem completely?

CharlesY · Oct 2, 2009

I suspect a carb problem, involving fuel starvation, low float level, and dirt blocking things up.

Take off the fuel inlet connection and see if there is a brass gauze filter in there. Clean it.

Take the top off the carb and set the float level, clean the fuel needle jet, and generally clean the whole damned thing inside and out. An air line and a blowgun does a great job.

The carb may be done - if it's a gonner get a replacement.

CharlesY

bowers1986 · Oct 2, 2009

Thanks very much charlesY,,, Just found a good diagram of the webber 34ich so will crack on with that tommorrow and report back here

Heres the diagram for anyone else needing it:
http://www.piercemanifolds.com/carbdetails/explviewparts/34ICH.pdf

CharlesY · Oct 3, 2009

Super, so now spot parts 17 and 19.

Is the lever dangling from 19 connected to the throttle arm by link 15?

Every time you open the throttle that link 15 should make lever 19 operate and force diaphragm 17 to fling a teaspoonful of neat petrol right into the airflow through the body of the carb.

Set the fuel float level then make sure no jets are blocked, and that the accelerator pump works. There's no magic to carbs. Just keep them clean inside and out.

CharlesY

bowers1986 · Oct 3, 2009

CharlesY said:
Super, so now spot parts 17 and 19.

Is the lever dangling from 19 connected to the throttle arm by link 15?

Every time you open the throttle that link 15 should make lever 19 operate and force diaphragm 17 to fling a teaspoonful of neat petrol right into the airflow through the body of the carb.

Set the fuel float level then make sure no jets are blocked, and that the accelerator pump works. There's no magic to carbs. Just keep them clean inside and out.

CharlesY

Cleaned the gauze filter, then removed top of carb and cleaned out,, found there to be quite alot of grit/dirt inside bottom of carb.Anyway fitted all back together and the problem looks to be solved as it doesnt go to stall when hitting accelerator like before,although the over heating problem persists, gonna do as you said with thermostat and see where we are tomorrow.

You say to set the fuel float level, can you enlighten me a bit on that charlesY,, I saw the float when removing the top of the carb but didnt touch it,,,I just pushed the priming handle after fitting top of carb back on to fill it with petrol.....then proceeded to start it,,?

thanks again mate

CharlesY · Oct 4, 2009

Ok ... overheating ... WEAK MIXTURE and / or RETARDED IGNITION.

make sure the ignition timing is right, but FIRST make sure the advance and retard mechanisn in the distributor is free to move.

Take "the breaker plate" out of the distributor and oil the bob-weights and springs under there, and make sure all the bits are free to move - rattling loose!

If the advance mechanism is stuck solid then even if you time it right, as soon as the engine revs pick up the ignition timing will not advance, and it will run retarded, and get very bloody hot. Pull a plug out and have a look. Take a photo of a plug tip and post it so we can have a look.

Drilling the stat will probably solve it if the problem was a blocked by-pass.

CharlesY

CharlesY · Oct 4, 2009

CharlesY said:
Ok ... overheating ... WEAK MIXTURE and / or RETARDED IGNITION.

Drilling the stat will probably solve it if the problem was a blocked by-pass.

CharlesY

But unless you PERSONALLY made sure the carb JETS were clear, it is too soon to assume they are.

The carb diagram will show you where the jets are and how to hoick them out. Don't poke them with anything harder than an airjet. NO poking them with pins or wires!

Attend to the parts numbered 6,7,8,9 and 10 very carefully.

CharlesY

bowers1986 · Oct 5, 2009

CharlesY said:
Ok ... overheating ... WEAK MIXTURE and / or RETARDED IGNITION.

make sure the ignition timing is right, but FIRST make sure the advance and retard mechanisn in the distributor is free to move.

Take "the breaker plate" out of the distributor and oil the bob-weights and springs under there, and make sure all the bits are free to move - rattling loose!

If the advance mechanism is stuck solid then even if you time it right, as soon as the engine revs pick up the ignition timing will not advance, and it will run retarded, and get very bloody hot. Pull a plug out and have a look. Take a photo of a plug tip and post it so we can have a look.

Drilling the stat will probably solve it if the problem was a blocked by-pass.

CharlesY

Will double check the timing with a strobe to make sure, as for the advance mechanism, the distributor is a brand new electronic one mate,, Unsure if theres any adjustment in this but will double check today. Certainly looks nothing like the one on the old distributor removed.

Thanks again for all your help,much appreciated

CharlesY · Oct 5, 2009

bowers1986 said:
Will double check the timing with a strobe to make sure, as for the advance mechanism, the distributor is a brand new electronic one mate,, Unsure if theres any adjustment in this but will double check today. Certainly looks nothing like the one on the old distributor removed.

Thanks again for all your help,much appreciated

It will still have a mechanical advance mechanism just the same.
It will be OK if it is new.
CharlesY

Timing a series 3 - Help needed plzzz

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