So I pulled out the mower to cut grass and would fired up then died so pulled again fired and died! Out of fuel, so fill it up and took a while to get going but it is surging massively had this before had it serviced and it still surged a little bit now itβs really surging! What can cause this air in system maybe dirt in carb?!
Cheers
Tried to add a vid but will try take a shorter 1 and add!!
Looks a pretty late model, you have checked filters etc ? take the top covers off and post a couple of pics of the carby. It may or may not have a mixture adjustment.
Does it have a paper or foam air filter ? if it's foam then check the manufactures recommendations. It will possibly say to clean and then oil the element, this in a way acts an air flow restricter which will richen the fuel mixture and will help with your issue.
Its a rapid start with primer wce, so will be a foam filter. Some of the ones I have seen on that sort of engine have been particularly nasty - worse than most side valve briggs engined filters
It is more than likely a bit of dirt/blockage in the carby. These carby's leave the factory borderline lean, to meet emission standards, it doesn't take much to block them and make them hunt. There are no adjustments on the carb and don't play around with the governor spring, it's most probably not the problem.As for the filter, clean and re-oil it but again a dirty/blocked filter will not cause it to hunt.
Well I pulled it out again today to mow other lawns and pulled off air filter cover and was pretty clean (only replaced last season) took off top cover and was fairly mucky so wdβd And cleaned up all moving parts! Works heaps better but still surging a little about what it has been for ages!!
Why must they dress them to look space age? Gullible consumers that's why! It's always the carburettors. A single point E.F.I powered by the engine as soon as you pull the starter would be the best solution. A set of button batteries to keep the computer chips active when the mower id off should suffice.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
Good to hear things have improved, did you oil the air filter ? noticed in your original post that the surging ( hunting ) problem was evident before you took it in for service and afterwards was greatly reduced. Did the service centre give you a diagnosis and remedy of the problem ? Given that there are no adjustments to fuel settings on this model it would be interesting to know if you first cleaned and oiled the air filter ( as this is the easier to do ) makes a difference and if not, cleaning of the main jet makes a difference. I agree with Bigted that the governor spring would be unlikely to be the contributor to the problem on this model engine.
The first time I went to get sorted they just did a service (oil, filter, plugs) I had made the mistake of tipping mower to clean after buying 2nd hand and fuel going through filter!!! Was filthy anyway! But they didnβt give me any other explanation! In my opinion it didnβt actually solve issue only improved it! Iβm thinking I will have to pull carb off and clean as something must have got through!
Surging is a sudden change of the fuel and air mixture during each complete cycle. Each intake stroke will sucks the mixture into the cylinder. Anything after the air filter will affect the control or governor and mixture ratio into the combustion. What factors that affect this? With newer engine it's unlikely to be the governor spring since its spring tension won't deteriorate that quick unless rusted or someone had stuffed it. Air leak on the manifold oring could affect the surging. Partial fuel blockage in the carburetor jet is one of the main problem. I don't recommend to oil the foam filter as this will attract dust and dirt that will restrict the air flow and makes the mower hard to start. Partially restricted air filter won't affect much on surging but will affect on revs and iddle. I have serviced 500e and 500ex but I can't seem to find a fuel filter in it. Could be inside the fuel tank but I haven't check it. Why I wondered because why everytime I rebuild this plastic carby there's always a dirt in the bowl and jet and how the dirt got in if the fuel is filtered? This type of carby doesn't have mixture adjustment. With the Classic/Sprint engine, surging is due to air leak through the diaphragm between the carby housing and fuel tank. Anyway I need an ignition coil for Briggs 500ex if anyone can sell. Please contact me.
Like all fault diagnosis it is a process of elimination starting with the simple. The air filter looks ok in the picture you posted Ollie but I would clean and oil the filter ( unless this has been done ) so it is as the manufacturer of the engine intended it to be to see if it makes any difference. Not everyone oils the foam filters for various reasons but it is interesting to note on the Briggs web page for servicing of air filters it states in capitals that foam air filters must be oiled to trap smaller dirt particles. I think a dry filter will allow a slightly greater volume of air to pass as opposed to an oiled filter. As Bigted pointed out these engines seem to be set very lean so any imbalances of ratios will have the potential to cause issues. If it makes no difference to the surge then it is ruled out as the cause and step 2, jet cleaning is done.
When I have this type of carby that is hunting at half throttle and up,I clean the fuel tank and fuel filter/strainer,air filter, ,fuel hose,then remove fuel bowl from carby ,clean carby then put some fuse wire up the main jet in the centre of the carby,work the wire in the jet hole until it's unblocked from the fuel bowl side.
If it hunts down lower there is a blocked idle/intermediate port. .The second carby pic is example only.(not the right mower carby)
When uploading a video,I just upload the video to YouTube then put the link address on this site when using full editor on reply. ( click insert media tag) Cheers Max
If it the above plastic carburetor and I think the 550EX is the 09P series engine the following service bulletin might need applying depending on the date code.
