Weber 34 ich - Problems running rich

MFC · May 7, 2017

Hi Guys - need some views on this.
Currently having a problem running rich (soot black plugs) finally leading to misfire caused by plugs too sooted up on a weber 34ich

Facts so far.

Mixture screw does nothing (or appears to do nothing)
Will run (just) with 2 turns on idle screw - note mixture comments above
Carb cover off and all ways cleaned and blown through
appears to run very sweet - just soots the plugs badly
living at 1000 meters (thinner air - but a factor?)
Timing appears OK and using electronic ignition
Air Filter not an issue as rich with K and N and none!
Idle jet is a 50 (should this be reduced down? what about main jets and air correctors?
No obvious leaks and checked by restricting airflow with hand and sucks well without and leak evidence
A lot of talk on float height, how the hell do you set that!!

Thanks as ever - as a non carb expert this one is a little confusing, Cheers

series2steve · May 7, 2017

right bud ,has it got a black plastic float?

MFC · May 7, 2017

Ahh, plastic for sure, I think it was white. The carb is 2010.

MFC · May 7, 2017

Sorry just found pic, will post late but yes looks black

series2steve · May 7, 2017

right then , fitted a new weber 2 years ago when i had the 2 and q engine, everything was lovely ,easy to setup ,better mpg ,awesome

after about a year started playing up ,flooding mainly ,wouldnt start ect.......

the problem was the float had split where the brass arm go in ,weighing it down and flooding float bowl ,and guess whats inside the float , ****ing sponge ,yep ,sponge

they must have thought "whats good at soaking up fluid, oooer , sponge"

i split it setting float level by grabbing the float and bending the arm, whereas the proper way is dont touch the float,bend arm with 2 pairs long nose pliers

i couldnt find the fault for ages as i thought the float was full of air and altho it felt a little heavy i couldnt hear petrol in it when shaking

new floats are £20 posted of ebay ,i ordered one and 2 in the box , so its here if needed £10 posted

MFC · May 7, 2017

This is the pic when I split it. One other thing, she was standing for a 3 years. There was some dirt in the float chamber but cleaned it out!

MFC · May 7, 2017

series2steve said:
right then , fitted a new weber 2 years ago when i had the 2 and q engine, everything was lovely ,easy to setup ,better mpg ,awesome

after about a year started playing up ,flooding mainly ,wouldnt start ect.......

the problem was the float had split where the brass arm go in ,weighing it down and flooding float bowl ,and guess whats inside the float , ****ing sponge ,yep ,sponge

they must have thought "whats good at soaking up fluid, oooer , sponge"

i split it setting float level by grabbing the float and bending the arm, whereas the proper way is dont touch the float,bend arm with 2 pairs long nose pliers

i couldnt find the fault for ages as i thought the float was full of air and altho it felt a little heavy i couldnt hear petrol in it when shaking

new floats are £20 posted of ebay ,i ordered one and 2 in the box , so its here if needed £10 posted

Thanks for the idea above - will have a look tomorrow, Never had a starting problem just the sooting of the Plugs, will report back thanks

MFC · May 8, 2017

OK Carb off and in bits - Float not cracked reset level to around 10mm to keep level lower, All cleaned and blown through, Only a crack on the idle jet O-ring so will replace and see but pretty sure it is still sealed as when undone half a turn the engine stops. All I can think of if waking in a new set of plugs and taking for a good test drive and seeing if still sooting up badly - Main Jet is 165 and Air bypass is 190. Idle as stated above is a 50. Any ideas on jetting or anything else greatly appreciated!! Thanks oh and pic of current set up

Dippypud · May 8, 2017

http://www.aloharovers.com/tech/ichoverhaul.htm

http://forum.landrovernet.com/showthread.php/70938-Weber-34ICH-Idle-Running-Rich

What air filter do you have ?

MFC · May 8, 2017

Was with a KnN but now original without any oil in so pretty unrestricted also have the crank breather not connected at the moment (see pic) so very unrestricted!

JimS · May 8, 2017

Altitude shouldn't be a factor at 1000M but you would normally drop one idle jet/main jet size (in steps of 5) for every 1000ft above 3000ft of altitude, and increase air jets by 2 steps (10) for the same.
I would think unless the jets have been messed around with, in all likelyhood it is something else though.

Dippypud · May 8, 2017

MFC said:
Was with a KnN but now original without any oil in so pretty unrestricted also have the crank breather not connected at the moment (see pic) so very unrestricted!

If it was jetted to suit the K&N and now it's rich, the fuel/air mix is wrong ...

Might need a different jet to suit the air coming in ...

MFC · May 8, 2017

Dippypud said:
If it was jetted to suit the K&N and now it's rich, the fuel/air mix is wrong ...

Might need a different jet to suit the air coming in ...

It was installed new out of the box in 2010 so not sure. current thinking is that maybe is was on the limit of rich at see level and the 1000 meter elevation increase has pushed it over the edge - to be continued

John S · May 9, 2017

The choke needs adjustment?

MFC · May 9, 2017

John S said:
The choke needs adjustment?

Have put new chake cable on and I think all ok and fully open!!! will double check as running out of ideas

Tall Ratbag · May 9, 2017

MFC said:
Have put new chake cable on and I think all ok and fully open!!! will double check as running out of ideas

Is the petrol pump correct?

The reason I suggest this is that the pressure spec for the petrol engine lift pump is 1.5 to 2.5 psi, while the diesel engine lift pump is 5 to 8 psi. A diesel lift pump, [or a diesel lift pump's diaphragm return spring] if fitted to a petrol engine would produce enough pressure to overcome the float valve in the carburettor.

This link may help - it states that fuel delivery pressure should be less than 3.5 psi

http://www.webercarbsdirect.com/v/vspfiles/images/Weber Trouble Shooting Guide.pdf

By the way, the jet sizes you quote sound right - or at least the same as the ones in my ICH, which runs OK.

JimS · May 9, 2017

Check the air correctors, the holes can be tiny, if they are gummed up this will cause a rich condition

MFC · May 9, 2017

series2steve said:
right then , fitted a new weber 2 years ago when i had the 2 and q engine, everything was lovely ,easy to setup ,better mpg ,awesome

after about a year started playing up ,flooding mainly ,wouldnt start ect.......

the problem was the float had split where the brass arm go in ,weighing it down and flooding float bowl ,and guess whats inside the float , ****ing sponge ,yep ,sponge

they must have thought "whats good at soaking up fluid, oooer , sponge"

i split it setting float level by grabbing the float and bending the arm, whereas the proper way is dont touch the float,bend arm with 2 pairs long nose pliers
Thanks will check - ok how can you tell???
i couldnt find the fault for ages as i thought the float was full of air and altho it felt a little heavy i couldnt hear petrol in it when shaking

new floats are £20 posted of ebay ,i ordered one and 2 in the box , so its here if needed £10 posted

Not having any luck sorting this one so if you still have the float I'll give it a go as someone said might have tiny ingress etc etc thanks in a

Tall Ratbag said:
Is the petrol pump correct?

The reason I suggest this is that the pressure spec for the petrol engine lift pump is 1.5 to 2.5 psi, while the diesel engine lift pump is 5 to 8 psi. A diesel lift pump, [or a diesel lift pump's diaphragm return spring] if fitted to a petrol engine would produce enough pressure to overcome the float valve in the carburettor.

This link may help - it states that fuel delivery pressure should be less than 3.5 psi

http://www.webercarbsdirect.com/v/vspfiles/images/Weber Trouble Shooting Guide.pdf

By the way, the jet sizes you quote sound right - or at least the same as the ones in my ICH, which runs OK.

Thanks for the idea - how can you tell the pressure at the carb any idea????

Tall Ratbag · May 9, 2017

MFC said:
Not having any luck sorting this one so if you still have the float I'll give it a go as someone said might have tiny ingress etc etc thanks in a

Thanks for the idea - how can you tell the pressure at the carb any idea????

I use an acient combined vacuum gauge / petrol pump pressure gauge, which I tee in to the fuel pipe to read the pump delivery pressure. But, assuming you don't have one, what you could do is to remove accelerator linkage and the two nuts holding the carb down, and lift the carb up an inch or so above the manifold. Then, have an assistant work the priming lever on the pump while you watch the bottom of the carb - no fuel should come out. As you may know, the pressure the pump delivers depends on the strength of the return spring, so, you should be able to build the pump's full pressure using the priming lever.

MFC · May 11, 2017

Tall Ratbag said:
I use an acient combined vacuum gauge / petrol pump pressure gauge, which I tee in to the fuel pipe to read the pump delivery pressure. But, assuming you don't have one, what you could do is to remove accelerator linkage and the two nuts holding the carb down, and lift the carb up an inch or so above the manifold. Then, have an assistant work the priming lever on the pump while you watch the bottom of the carb - no fuel should come out. As you may know, the pressure the pump delivers depends on the strength of the return spring, so, you should be able to build the pump's full pressure using the priming lever.

Thanks for this - lifted the carb and cranked over both by hand and with the SM, nothing came out - will do service and see if anything chages!!! thanks again

Weber 34 ich - Problems running rich

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