Briggs 16HP Vanguard carb / fuel problem

[Forest#2]

Hard to tell for sure but I seem to detect that it's only running on one cylinder sometimes maybe. (or one cylinder is weaker) You can judge such by rpm drop as each cylinder is disabled, comparing one to the other.

You can easily confirm such by sliding back the rubber boots on both spark plugs so as to see the metal ends while on the spark plug and while the engine is running at idle ground each spark plug wire one at a time using a long blade screwdriver. If grounding one spark plug wire immediately starts killing the engine that is the ONE CYLINDER that it's using to run.
The cylinder that makes no difference when it's spark plug wire is grounded is the dead or weak cylinder.

Lightly lubing the spark plug wire itself just above the boot helps when sliding the boot back. (another way is to allow a small solid wire to stick out of the boot and ground the wire while it's running.
Just because you see a spark at both plugs IS NOT sure indicator that both cylinders are actually producing power. The other way is to use a fuse puller and momentarily pull the spark plug wire off the plug. I do not like to pull a plug wire for testing while running, I prefer grounding but sometimes I have no other choice.

 

[RevB]

Hello All - am hoping the knowledge bank here may be able help. I'm resurrecting a John Deere LT166 lawn tractor with 16HP Briggs engine. It has sat for 2-3 years but was running fine, save for a snapped deck belt, previously. I've stripped and cleaned the carb and got it started, driving and mowing, but not very well. It basically won't run properly without choke. I've double checked the jets in the carb. I can just about get it to tick over without choke by adjusting the fuel screw, but it won't rev and it's obviously running far too rich. In any other position it won't even idle, or only for 10-15 secs before stuttering and dying. With choke it will rev, but is maybe at 30% power and clearly not running as it should. Oddly it can manage forwards, but reverse pretty much kills it.

Have I missed something on the Aisan carb? I thought maybe a fuel pump issue but if it runs at full revs, albeit it badly, it can't be? I've checked the tank cap breather as well. It has clean fuel, albeit mixed with whatever small amount of bad might have previously been in the tank, but I think it was bone dry. Is there a hidden jet anywhere on those carbs?

Thanks in advance...!

Are those composite floats or just really crusty brass floats? The composite floats are sometimes like the Bing composite floats and they absorb gas after the surface sealing fails making the float too heavy and the needle never closes. Thus, too rich as you say it appears to be.

 

[Gord Baker]

142 is the emulsion tube. It has super tiny holes so be thorough. Use a magnifying glass and fishing line to verify holes are open. Start saving bread ties. They have small gauge wire under that plastic coating. I found a couple that work great for this. You might have to use a radiator hose angled pic tool to get the emulsion tube out.

Wear safety glasses when spraying carb cleaner. Face shield even better. That stuff burns the eyes let me tell you.

The wires on a Wire Brush work well for poking through these holes. Some jets on the bottom of the float bowl have a very tiny hold on an angle in the threads.

 

[Gord Baker]

I hope you changed out the Fuel Filter.

 

[STEVES]

I haven't fired compressed air through there yet but it has had a load of carb cleaner through. I'll also try compressed air in case the carb cleaner hasn't moved something, plus a wire guitar string I've found works well. I've pictured the fuel screw port in the venturi below, what do those three just visible (hard to get phone to focus!) behind do? They're connected to 72 in the diagram via a channel (showing in pic 1 top of carb) in the carb body - again all blasted through with carb cleaner and apparently clear.

The fuel screw was doing little previously, but now if I lean it off too much it stalls, so is working at the least in part.

Flywheel - haven't got in that far yet, will check and also do fins if clogged. Valve clearances likewise.

Will also check float level. Disconnecting the solenoid kills the engine, but I'll check the voltage to see if constant. I'm twisting the carb once it's off the engine to unscrew the bowl, as I can't see a way to easily disconnect the solenoid wiring at the solenoid. Twisting the solenoid will have twisted the wire and stressed the connection over time / previous owners I'm sure.

@Forest#2 was there info missing from my last? I will check tomorrow in daylight again. Noted re welch plugs, thanks for the tip!

Appreciate your continued help!

Narrow (thin, flat) 1/2" wrench fits at the top of solenoid at bottom of bowl to remove

 

[ft_motors]

Hello All - am hoping the knowledge bank here may be able help. I'm resurrecting a John Deere LT166 lawn tractor with 16HP Briggs engine. It has sat for 2-3 years but was running fine, save for a snapped deck belt, previously. I've stripped and cleaned the carb and got it started, driving and mowing, but not very well. It basically won't run properly without choke. I've double checked the jets in the carb. I can just about get it to tick over without choke by adjusting the fuel screw, but it won't rev and it's obviously running far too rich. In any other position it won't even idle, or only for 10-15 secs before stuttering and dying. With choke it will rev, but is maybe at 30% power and clearly not running as it should. Oddly it can manage forwards, but reverse pretty much kills it.

Have I missed something on the Aisan carb? I thought maybe a fuel pump issue but if it runs at full revs, albeit it badly, it can't be? I've checked the tank cap breather as well. It has clean fuel, albeit mixed with whatever small amount of bad might have previously been in the tank, but I think it was bone dry. Is there a hidden jet anywhere on those carbs?

Thanks in advance...!

If it's running rich, most likely the air jets are plugged.

 

[S.A.P.]

Hello All - am hoping the knowledge bank here may be able help. I'm resurrecting a John Deere LT166 lawn tractor with 16HP Briggs engine. It has sat for 2-3 years but was running fine, save for a snapped deck belt, previously. I've stripped and cleaned the carb and got it started, driving and mowing, but not very well. It basically won't run properly without choke. I've double checked the jets in the carb. I can just about get it to tick over without choke by adjusting the fuel screw, but it won't rev and it's obviously running far too rich. In any other position it won't even idle, or only for 10-15 secs before stuttering and dying. With choke it will rev, but is maybe at 30% power and clearly not running as it should. Oddly it can manage forwards, but reverse pretty much kills it.

Have I missed something on the Aisan carb? I thought maybe a fuel pump issue but if it runs at full revs, albeit it badly, it can't be? I've checked the tank cap breather as well. It has clean fuel, albeit mixed with whatever small amount of bad might have previously been in the tank, but I think it was bone dry. Is there a hidden jet anywhere on those carbs?

Thanks in advance...!

Sounds like a head gasket issue.
Probably got full of thum grass clippings and oil, and ran too hot.
Once the covers been removed of course, things can be observed, flywheel magnet, coil, and any foreign matter trapped in the cooling fins. Some compressed air, or (pressure washing) works, (remove the coil first) to get the gunk off.

 

[barny57]

Hello All - am hoping the knowledge bank here may be able help. I'm resurrecting a John Deere LT166 lawn tractor with 16HP Briggs engine. It has sat for 2-3 years but was running fine, save for a snapped deck belt, previously. I've stripped and cleaned the carb and got it started, driving and mowing, but not very well. It basically won't run properly without choke. I've double checked the jets in the carb. I can just about get it to tick over without choke by adjusting the fuel screw, but it won't rev and it's obviously running far too rich. In any other position it won't even idle, or only for 10-15 secs before stuttering and dying. With choke it will rev, but is maybe at 30% power and clearly not running as it should. Oddly it can manage forwards, but reverse pretty much kills it.

Have I missed something on the Aisan carb? I thought maybe a fuel pump issue but if it runs at full revs, albeit it badly, it can't be? I've checked the tank cap breather as well. It has clean fuel, albeit mixed with whatever small amount of bad might have previously been in the tank, but I think it was bone dry. Is there a hidden jet anywhere on those carbs?

Thanks in advance...!

Hello All - am hoping the knowledge bank here may be able help. I'm resurrecting a John Deere LT166 lawn tractor with 16HP Briggs engine. It has sat for 2-3 years but was running fine, save for a snapped deck belt, previously. I've stripped and cleaned the carb and got it started, driving and mowing, but not very well. It basically won't run properly without choke. I've double checked the jets in the carb. I can just about get it to tick over without choke by adjusting the fuel screw, but it won't rev and it's obviously running far too rich. In any other position it won't even idle, or only for 10-15 secs before stuttering and dying. With choke it will rev, but is maybe at 30% power and clearly not running as it should. Oddly it can manage forwards, but reverse pretty much kills it.

Have I missed something on the Aisan carb? I thought maybe a fuel pump issue but if it runs at full revs, albeit it badly, it can't be? I've checked the tank cap breather as well. It has clean fuel, albeit mixed with whatever small amount of bad might have previously been in the tank, but I think it was bone dry. Is there a hidden jet anywhere on those carbs?

Thanks in advance...!

A new carb kids only from 10 to 15 bucks I just replace the parts

 

[Freddie21]

I have the exact problem with a Kohler SV590 19hp. The governor brackets were previously adjusted and I think I got them close. Almost idles with choke partically on, spits fuel out when throttle increased. More than one OEM carb and one China carb. Mine does have a mixture screw, but little affect. For the cheap price, try another carb and see if problem changes. Like mentioned, Amazon will take the return.

 

[Wurzel]

A new carb kids only from 10 to 15 bucks I just replace the parts

Having some trouble finding a compatible one, the linkages are top mounted on most of the ones that claim to be replacements...