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Hi, wonder if anyone can help…?
Westwood T1250 ride on mower. UK. Koehler command 12.5 engine, runs ok, but lately has started throwing neat fuel out the exhaust when starting on choke from cold. But get the engine spinning on the starter, then apply the choke slowly then back the choke off once it fires and it’ll run fine, with minimal splutter and smoke from cold. If giving full choke it seem close to hydro locking and the starter motor will struggle, it will splutter badly, and heavy grey smoke is evident until it clears with choke off.
Any advice before I fiddle with it and cause more issues?
It’s running 10w 40 oil at the moment, as the manual says is ok to use, but does advise starting will be more difficult in cold weather, which it is. But ok in summer now. The thinner oil (5w 30? ) will go back in soon before it gets colder.

it will also stall on minimum throttle, where it used to be fine.

Ta

Cv1259T seems to be the engine model

Check the oil level
Probably will be high.
Float is sticking in the carburettor allowing neat fuel to drip into the engine
It will get worse and can destroy the engine

bertsmobile1 said:

Check the oil level
Probably will be high.
Float is sticking in the carburettor allowing neat fuel to drip into the engine
It will get worse and can destroy the engine

Click to expand...

Ok thankyou… yeah I had a DT 125 that did that…come back to it after a lay up and it would be hydro locked, so you had to take the plug out and kick it over until it cleared the fuel out the plug hole.

…on the Koehler though, fuel out the exhaust only happens on choke. Spin the engine without choke from the outset and nothing unusual happens. Open the throttle lever a bit further, still nothing, then you get to the choke range of the throttle lever and all the fuel arrives at once and out the exhaust comes near fuel….I’m just thinking If float was sticking would it not drip fuel all the time and have fuel in the cylinder from outset, rather than just on choke. ….? But no matter, really. Into the carb we go.

1. Your float system is bad, which allows an immoderately high fuel level. Not high enough to leak, but higher than required so that the choke draws in too much fuel.
OR
2. Your air filter needs replacing. Inability for air to enter means that more fuel is ingested, in the place of air.

Sorry chaps had trouble logging in

yes you were correct with your diagnosis. Took the air cleaner out and there was fuel sitting in the inlet. There’s a depression in the ventrury allowing fuel to puddle. With choke open the air speed through the crab isn’t quick enough to pull that puddle of fuel through. But apply choke the air speed quickens and whoosh all the fuel is dragged through.

fairly easy to pull the carb off to clean the float jet, blow thorough and test by blowing and sucking through the fuel line inlet by mouth to confirm it’s seating well. Good vacuum with the carb the right way up suggests to me the float valve is seating.
But I’ll whip the air filter out and check it again before next start up to be sure it’s stayed fixed and haven’t leaked though again.
I’m a bit concerned how to get the jets out thought. A new float needle I’m sure can be purchased and replaced but if it’s the seat that’s worn there appears to be no way to unscrew the seat/jet to fit a replacement ?
Is it a case of a new carb? That might be considered disappointing if so.

thanks for advise though. Oh and oil was on the upper mark? Too high?

Hi thanks for reply

came back to the machine today. Popped the air filter out and fuel in the carb inlet clearly visible again

new float needle it is
If I can find one

The fuel level should be about 1/8" below the float bowl gasket, which would place it about 1/4" below the interior of the carb.... So YES, your float level is WAY too high.

A good rule is to turn OFF the fuel when you finish mowing and allow the engine continue to run as you walk back to the storage shed or garage. This pulls the fuel level down, which drops the float, which then releases the pressure on the float needle, which makes those delicate viton tips on the float needle last longer. This procedure requires the presence of a manual fuel shut off valve, which is s a very good thing to have. About $8 anywhere.

I my personal view, if your mower/ tiller/ generator has an external 'rubber' fuel line, then you should have a manual fuel shut off valve AND a fuel filter. Having those 2 items would end about 40% of the common issues associated with small engines.

Born2Mow said:

• Most jets are cleaned in-situ. Those few that unscrew are obvious from their hex shape or screwdriver slot.
• Most modern float needles are tipped with soft viton, making float needle replacement MORE common, and float needle seat wear a thing of the past.

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Unless they are recessed with a screw driver slot…. Or no slot as in this case ?

Born2Mow said:

The fuel level should be about 1/8" below the float bowl gasket, which would place it about 1/4" below the interior of the carb.... So YES, your float level is WAY too high.

A good rule is to turn OFF the fuel when you finish mowing and allow the engine continue to run as you walk back to the storage shed or garage. This pulls the fuel level down, which drops the float, which then releases the pressure on the float needle, which makes those delicate viton tips on the float needle last longer. This procedure requires the presence of a manual fuel shut off valve, which is s a very good thing to have. About $8 anywhere.

I my personal view, if your mower/ tiller/ generator has an external 'rubber' fuel line, then you should have a manual fuel shut off valve AND a fuel filter. Having those 2 items would end about 40% of the common issues associated with small engines.

Click to expand...

Orders yesterday as it happens ?
Filter is already installed

Chrisgixer2 said:

Unless they are recessed with a screw driver slot…. Or no slot as in this case ?

Click to expand...

IF there is no way to physically remove the jet, THEN they must be cleaned in-situ... just like I said. This type carb design/manufacturing is becoming more common. They simply want you to buy a new carb every year.

Born2Mow said:

IF there is no way to physically remove the jet, THEN they must be cleaned in-situ... just like I said. This type carb design/manufacturing is becoming more common. They simply want you to buy a new carb every year.

Click to expand...

If it’s recessed, as this one is, then it wouldn’t be OBVIOUS …. Was my point

i presume they press the jets /seats in

carb float valve holds pressure over night. currently looking at fuel pump leaking into crank case, or somehow over presurising the float needle while the machine is stood

OK, now that we understand each other.... (Brings back the thought of Churchill's famous quote..)

1. The float valve really can't restrain that much fuel "pressure". The modern float needles with the viton tip do better than the older metal and nylon versions, but still the "pressure limit" on fuel going into the carb has to be well below 1-2 psi. This is one reason for the fuel shut-off valve, whether manual or 'automatic', and/or the fuel pump. And by this last bit I mean that designers know that float valves are a weak point in the system, and so they purposely place the fuel tank BELOW the carb. In these designs, the fuel must be pumped up to the carb. Thus, when the pump (the engine) is turned OFF, excess fuel into the engine also stops.

When the fuel tank is placed above the carb, and sometimes this can't be done any other way [think motorcycle], fuel On/Off valves must be present. So the whole point of this is to say don't expect heroic efforts from your float needle. It's not within the realm of possibility. Therefore, high fuel levels in the carb must be the fault of something else. High fuel levels is then simply a symptom, not a direct cause.

2. So the photos of Westwood T1250's that I see, show a fuel tank above the level of the carb. You may have an automatic fuel shut off valve, but you'll need to add a manual in-line fuel shut off valve. This because 1) the automatic fuel valve cannot be trusted after a year in operation, and 2) you can't easily detect what effect that valve is having.

3. In addition, you cannot be sure that small grit has not entered the fuel system. So if you do not have an in-line fuel filter, then one needs to be installed. Installation of a filter simply adds a measure of insurance. Both the filter and manual fuel valve are inexpensive items.

4. Then, so that we can start "fresh" from the beginning, I would install a new carb float and float valve.

5. Lastly, and most importantly, I would begin a new operating procedure. One which will further insure your success. And here I assume you are some distance from your garage or storage shed where you park your mower. When you finish mowing, manually turn OFF the fuel. The engine will be able to run another 4-6 minutes without issue. During your drive back to the storage area, your float bowl will be emptied. This relieves the fuel pressure on the float system and insures the carb will NOT be flooded with fuel when you go to start the engine on the next day of use.

Implement these steps and your problems will be over, my friend.

Chrisgixer2 said:

If it’s recessed, as this one is, then it wouldn’t be OBVIOUS …. Was my point

i presume they press the jets /seats in

Click to expand...

Yes they are and they are replaceable on the Walbro carburetors. So when installing a new seat the height setting important. The kit PN is not listed on the parts IPL normally.

Here is how to check the current setting. I error toward the lesser setting instead going for the larger setting.

Honda issued a nice tool for measuring that.

Just to say, finally able to log in again, after numerous attempts emailing admin, after a received an email comedy thread link out of the blue…. And to say Thankyou for your help, I did manage to set the float as the diagram. Cheers all.