Hi every one,i am having trouble with the engine in the mtd ride-on.i used the mower on a job for 2 hours straight,no dramers,then just at the end it started to run rough emmitting puffs of black smoke(running rich)at home i changed the fuel filter-gapped and fitted both spark plugs(ngk)removed carby-dismanteled it and cleaned all passages-jets checked float level etc.the problem is when you start it it will run for about 10 sec then stop,no cough or splutter and i also bypassed the (water in fuel sensor)the fuel pump works fine-new fuel filter-new plugs-oil light goes out when started-tried using choke/no choke.being a v-twin the engine ran really smooth and now i am at a loss...ken
Ken, I agree that black smoke almost always means rich mixture, except when it means leaking exhaust valves. I take it there was no black smoke, and it ran properly, until some sudden failure caused it to start smoking. Please confirm that when it does this, the exhaust smells rich - the smell is quite distinctive.
There aren't many things that can happen suddenly to an engine to make it run rich. A jet, flow restrictor or mixture adjusting screw in the carburetor coming loose could do it, or the carburetor could have started to flood. Flooding is the most likely problem. There is an easy way to check. I suggest you do two tests. First, park the mower on level ground, remove the air filter so you can look into the carburetor throat, turn on the fuel, and wait a few minutes. If fuel runs out of the carburetor, or down the throat into the intake manifold, it is flooding. The second test is to turn off the fuel with it running at mid-range speed, so the fuel level in the float bowl gradually drops. If it is rich, it will slowly run better, then run properly for a little while, then go lean and stop. If you do both tests you should be able to confirm (or reject) the theory that it is running rich, and see whether it is due to flooding. If it is flooding, something has gone wrong with your float, float lever, float needle, or float bowl fuel seat.
Hi grumpy,the carby has a external over flow tube,i did make it flood out the tube deliberatly to see if it works and reset float level.when it started blowing black smoke i could not smell it and the old plugs where covered in dry black soot and you could here one or both cylinders missing reguarly.now i have new plugs the engine runs very smooth then stops.ps i even removed the tank cap and also tested the fuel pump presure which is good.i had a look at the briggs site to no avail...ken
Rich mixture normally smells like rich mixture Ken. Soft black carbon that forms quickly on new spark plugs usually means it is rich, but if it is rich enough to blow black smoke, it should not be running smoothly, it should be rolling, slowing down, and generally acting like an engine with too much choke applied. Have you tried running it with the fuel tap turned off? It can't stay rich for very long with the fuel off.
with the new plugs in it runs like it should and starts on half a rotation.tommorrow i will remove the carby and check that the float is not sticking closing off the needle and seat and i will take some pics of bits and pieces.going to bed now-too tired...ken
morning grumpy,the motor does not run rich or blow black smoke,it starts then just stops.can you or bruce advise me of the float height measurement so i can double check thanks...ken
Ken, all of the various types of flo-jet B&S carburetor do not have a float level specified in the manual - the only specifications are that the seat must be pressed into the top of the body until level with the surrounding metal, and the float must be parallel to the top of the body when the needle is closed.
Float level will not be the problem if the engine starts then stops. It is just about certain to be either ignition or fuel supply, and fuel is more likely than ignition if this happens consistently each time you start it and it never misfires or runs on one cylinder. If you disconnect the fuel hose from the carburetor, turn on the fuel tap and let the fuel flow from the hose into a jar, does it flow steadily? If not there is an obstruction in the tank, or the tank is empty. If it passes that test, and if the passage from the fuel hose barb through the needle and seat is not blocked with gunk, it is heading toward being an unusual case.
What setting are you using for the main jet adjustment? Since you have dismantled and reassembled everything, it may require resetting to the starting point and re-tuning. And can we have a picture of the carburetor please, so we will know which model it is?
hi,you would not believe it but what i thought was the (water in fuel)sensor at the bottom of the float bowl is a fuel cut off valve powered by 12 volts.it is not working so i removed it and used a small bolt to hold the fuel bowl on and now the engine starts and keeps going as per normal.i will get a new solonoid soon.now the engine is still running rough so i will clean the other set of plugs and see what happens.my next thought would be adjusting the valves but i will need bruce to supply a manual for the vanguard v-twin engine...ken
The float bowl solenoid on the Intek OHV V-twins seems to be an anti-dieseling device, and from what I've read on the internet, it is not unusual for the solenoids to fail either partially or completely, causing non-starting in extreme cases, or fuel starvation under load in very mild cases. If your Vanguard engine has one of them, it does sound as if you will need to replace it - you cannot allow the engine to diesel when you switch it off, because it may cause damage.
Ken, the URL below has some valve clearance data for B&S engines. I can't tell you which one to use without knowing your model number. You may need to be extremely accurate with the exhaust valve clearance: the Intek engines' decompressor does not operate if the clearance is the slightest bit too large, causing what seems like serious electrical problems but isn't. I don't know if the Vanguard is the same. http://outdoorpowerinfo.com/engine_specs/briggs_valve_gaps.asp
Hi grumpy,with all the stress of life and trying to repair your own equipment.some times i need to stand back and take a breather.i thought by blowing through the air filter it was ok,on removing the (dirty)filter the engine ran smooth as so $60.00 later with the new filter in i mowed for 2 hours with no hiccups at all.such a basic item over-looked by myself.thanks grumpy and i am always learning until i am pushing daisies...ken
