Brigg Stratton Quantum XM50 smoke and won't rev on lawnmower
- Thread starter Jonny Vee
- Start date
-
- Tags
- carburetor mower
Whereas the Quantum was suffering from excess fuel, with the Webb it’s the opposite - not enough juice is getting through.
Basically the engine can’t suck enough fuel through the main jet, followed by the emulsion tube above it......both need cleaning with a toluene based cleaner and preferably compressed air. I’m afraid it’s almost impossible to clean the emulsion tube without it.
Likewise the float needle valve must be clean.
John
Basically the engine can’t suck enough fuel through the main jet, followed by the emulsion tube above it......both need cleaning with a toluene based cleaner and preferably compressed air. I’m afraid it’s almost impossible to clean the emulsion tube without it.
Likewise the float needle valve must be clean.
John
John, never used Toluene. Is this available to buy somewhere?
Aerosol carb cleaner, available at any motor factors! This stuff will dissolve almost anything.
Brake cleaner is a similar product and works just as well.
John
Brake cleaner is a similar product and works just as well.
John
- Joined
- 7 Sep 2022
- Messages
- 2,764
- Reaction score
- 708
- Country
Sounds like the engine is only able to run off the fuel ending up in the cylinder from the primer bulb - does it remain running if you pump the primer repeatedly while it is running? Perhaps the main jet is blocked..
I thought was different cleaner. The main jet was already cleaned with carburetor cleaner and air compressor but has not improved the situation
How about the emulsion tube above it, Jonny?
Feel free to poke any holes you see with fine fuse wire......this item does play an important role.
Regarding the replacement carbs.......I have bought several Zama type carbs for very little money off ebay, amazon or whatever and I've only had one dud. How they can be made / shipped / shopped for the price is anyone's guess.
John
Feel free to poke any holes you see with fine fuse wire......this item does play an important role.
Regarding the replacement carbs.......I have bought several Zama type carbs for very little money off ebay, amazon or whatever and I've only had one dud. How they can be made / shipped / shopped for the price is anyone's guess.
John
Just for interest......if the carburettor floods or misbehaves, people don't realise the rubber needle seat is actually there - it's so easy to lose.
I'm not saying this is your problem as not all carbs have it. It's the tiny green thing, but most are red!
www.gardenhirespares.co.uk
John
I'm not saying this is your problem as not all carbs have it. It's the tiny green thing, but most are red!
Genuine Briggs & Stratton Needle & Seat Kit - 394681
Genuine Briggs & Stratton part suitable for some of the following models;170400, 170401, 170402, 170403, 170404, 170405, 170407, 170411, 170412, 170414, 170417, 170431, 170432, 170434, 170435, 170436, 170437, 170451, 170452, 170457, 170701, 170702, 170703, 170704, 170705, 170707, 171431, 171432...
Just for interest......if the carburettor floods or misbehaves, people don't realise the rubber needle seat is actually there - it's so easy to lose.
I'm not saying this is your problem as not all carbs have it. It's the tiny green thing, but most are red!
JohnGenuine Briggs & Stratton Needle & Seat Kit - 394681
Genuine Briggs & Stratton part suitable for some of the following models;170400, 170401, 170402, 170403, 170404, 170405, 170407, 170411, 170412, 170414, 170417, 170431, 170432, 170434, 170435, 170436, 170437, 170451, 170452, 170457, 170701, 170702, 170703, 170704, 170705, 170707, 171431, 171432...
John, Thanks for the tips. How you normally know if a carburettor have a rubber needle?
I did this test and if I keep pumping the primer the engine last for an extra second or two and stops
If you take the float bowl off and with the petrol supply on, lifting the float should stop the flow of fuel.
If the rubber seal isn’t there, the fuel should still pass to some degree.
That’s about the only check you can do, I think.
Do the model numbers given apply to your machine?
John
Low fuel level in the float bowl, I suspect so check the needle valve for good flow.
Failing that, we’re back to the main jet and emulsion tube, I’m afraid!
John
John, took me a lot of patience but in the end works. It was the emulsion tube not perfectly clean which made me mad.
Thanks everyone this now works fine.
Still awaiting the carburetor for the Quantum.
I'm also fixing a briggs classic 35. It idle fine but won't accelerate. Only accelerating if I move the governor.
Is this a linkage or diaphragm issue?
I guess this is the side valve motor, with the carb sitting on top of the fuel tank?
If it is, remove the carb, check the filter(s) on the end of the dip pipe(s) and replace the gasket and diaphragm between the two.
Make sure the rubber breather pipe is in place too!
Early carbs had two brass dip pipes and two filters....the later one just one of each. These are nylon now.
Pleased you sorted the emulsion tube issue - those tiny holes are just crazy to clean.
John
If it is, remove the carb, check the filter(s) on the end of the dip pipe(s) and replace the gasket and diaphragm between the two.
Make sure the rubber breather pipe is in place too!
Early carbs had two brass dip pipes and two filters....the later one just one of each. These are nylon now.
Pleased you sorted the emulsion tube issue - those tiny holes are just crazy to clean.
John