Thread: carby problems with Lucas

Check the throttle butterfly pivot points. If they are worn you get airflow through them which allows incorrect fuel/air mixture. And also allows backflow back into engine when shutdown.
Just a thought.

Originally Posted by Lyle

And also allows backflow back into engine

Plenty of that happening
Did this about 18 months ago and cost hundreds of $ to fix
The mill has done very little work last few months and i am wondering if the fuel has become gummy and caused the fuel float to stick
I always keep carby clean and the filter replaced regularly
Old 'Murphy's law follows me round like a smell at times
Thanks for the advice thus far folks...muchly appreciated...MM

Needle and seat problems will allow uncontrolled fuel flow and a leaking float will do the same thing. Pull the float bowl off and you can remove the float and give it a shake to see if has fuel in it. Next pull the needle out of the seat and make sure there is no debris lodged in the seat where the needle seals and none on the needle. Check that the seat is not damaged such as nicked or cut and give everything a blast of compressed air if you can. If all is well hook up the fuel line with the N&S and float assembled but don't put the assembly back on the float bowl, hook up the fuel line and let the fuel flow through then push the float to stop the flow. If the flow does not stop completely you need a new N&S. If the float has fuel in it when checked it can be removed by putting it in boiling water and the fuel will come out of the hole in the float. Nail polish is a good sealer if it has a hole that needs sealing.

Put the whole lot back together and ideally blow out the excess fuel from the motor with compressed air leaving the plug out. If that is not possible give it a heap of pulls with no plug in it, making sure the plug is earthed to the motor and then try starting it. If really flooded a good trick is to clamp the fuel line and keep pulling it until it starts then release the clamp. Make sure the air filter has not become saturated with fuel also as that will also prevent it from starting.

As Chris suggests, but change the oil if there is any evidence of fuel in the oil. Fuel diluted oil will not have the same lubrication qualities and the motor may be damaged by insufficient lubrication when you get it going.

A filter change after a short run would be worthwhile as well as fuel contaminated oil may have loosened deposits in the sump etc and have them ready to start clogging the existing filter. Concept is a short, no load run to circulate the oil, then change the filter and top up the oil. Hopefully, most loose debris would end up in the original filter, and the replacement should get a reasonable service life.

I took it to be two stroke???

Originally Posted by Chris Parks

I took it to be two stroke???

Haven't been around Lucas' much, mainly watching them at shows etc, while I stump up courage to ask SWMBO, but there are a range of models with varying blade sizes, cutting capacities, and motor sizes. All that I have come across have been 4stroke industrial class twins, but I have heard people mention electric motors for non mobile applications.
There are also slabbing units which are basically a 4 stroke powered outsized chain and bar set up on a trolley to operate on the rails etc of the swing saw.

If it's been sitting around with stale fuel in it that may be the most likely cause. I always drain fuel after use. If I dont, I can count on a s#*t fight getting her started after a prolonged rest up. Fuel these days aint what they used to be. A mate , who runs a small motor repair business, says modern fuel has increased his business by at least fifty percent and always recommends full draining of the system after use.

Using E10 I can see that might be an issue as it is partly hydroscopic due to the Ethanol component. Having said that I haven't experienced it my self on motors that don't get used much. Did you get it going Mapleman?

This is my "it's not starting" cure - works quite well on the lawnmower that's been sitting all winter - Start Ya Bastard Instant Engine Starter - Nulon Products Australia

All fuel companies recommend NOT to use E10 in small engines, E10 must be marked on the bowser. Boat engines hate E10. Watch for some some higher octanes using ethanol to increase the octane rating, you may have to look closley on the bowser to see this. Basically ethanol absorbs water, as perviously stated, where straight ULP will not mix. Stick to the major brands, everyone uses the same fuel, the larger band use better additives. Cheap fuel at the bowser is not always cheaper in the long term. I find sometimes, engines need to either talked to nicely others need to be threatened with large screwdivers and even bigger hammers.

Tapped carby with hammer a few times
Up and running now
Go figure
Needle and seat may well have been the problem...MM

Simple fixes are always the best.

Originally Posted by MAPLEMAN

Tapped carby with hammer a few times
Up and running now
Go figure
Needle and seat may well have been the problem...MM

Sounds like another fuel gum up. I've never used E10 but even the best of them these days are quick to gum up. Fuel storage life is nothing compared to what it used to be.
A plumber mate, who worked for Shell until recently, and does a lot of "outside" fishing, reckons he would never store an outboard with fuel in it due to the modern additives, not even overnight.
I run two Lucasmills, concrete mixer and lawn mower, all start easy when I drain them.
Leave 'em and its a Pullers Fest to get any of them going.

Never had a single days problem starting either of my two Lucas Mills which had carby's, so unfortunately can't really offer much help. But having said this maintenance and cleaning the gear regularly is always the best preventative medicine...