Briggs 16HP Vanguard carb / fuel problem

[STEVES]

Cleaned debris & grass from fuel tank, ran carb through ultra sonic cleaner 3 times, blew lines & carb. Did it again, blowing again back, sediment bowl & HEY, out comes another blade of grass!!! So, yes,
possible something missed. Engine ran 10 to 20 minuets & popped - died. Silly blade of grass!! If 1st don't succeed, try try again, don't go off course chasing something else.

 

[slomo]

Cleaned debris & grass from fuel tank, ran carb through ultra sonic cleaner 3 times, blew lines & carb. Did it again, blowing again back, sediment bowl & HEY, out comes another blade of grass!!! So, yes,
possible something missed. Engine ran 10 to 20 minuets & popped - died. Silly blade of grass!! If 1st don't succeed, try try again, don't go off course chasing something else.

OP has 2 accounts.

Thanks for letting us know.

 

[Forest#2]

Few pages back you said you see a welch plug leaking air.
How did you re-seal the welch plug? (plugs)


It appears maybe that carb has a 3 piece High speed main jet area, emulsion tube, Main jet and a high speed adjustable H jet in the bottom of the bowl.
Post up some pictures of these 3 pieces showing the tip of the H jet.

 

[slomo]

Few pages back you said you see a welch plug leaking air.
How did you re-seal the welch plug? (plugs)

Jumping in here, Briggs recommends clear nail polish to seal welch plugs.

 

[Forest#2]

Jumping in here, Briggs recommends clear nail polish to seal welch plugs.

The reason I asked is he said in a previous post few pages back he placed his finger over a leaking welch plug and it made no difference. (so he just moved on)

He needs to re-check/re-seal the welch plugs especially after using high pressure compressed air into the carb.

 

[Wurzel]

I sealed the welch plug up with a cap of glue as temporary measure, I'm certain it was now airtight.

@Forest#2 you mention a high speed adjustble jet, which are you referring to? The one in the bottom of the bowl (254 below), I undertood to just be a drain plug, certainly loosening it means fuel leaks from the perpendicular drain hole it covers. If the high speed is adjustable, that would seem a very obvious thing to look at.



I've put the carb into boil again and attach photos of the main jet, emulsion tube and the screw marked 254 above. Once back together I'll hook up to a temporary supply to see if there's a difference.

Meanwhile the float jet and it's seat are clean and flowing freely.

I haven't yet drained the tank and refilled it through a coffee filter, if the temporary fuel supply yields a different result, I will.

I've also included a photo of the air side showing the internal ports in the body, again all cleaned and flowing with carb cleaner, but as I've said previously, there are passageways on top that I can get carb cleaner through, but can't see through or wire through.

As I've said before, I appreciate your help here and yes, it's quite possible I may have missed something. but this issue is deeply frustrating and I am not ignoring advice. I'm not a mechanic, so am acting on the advice given to the best of my ability.

 

[Forest#2]

Yes, that is just a bowl drain. #254
Your High speed jet is the one that screws into the side of the carb in your picture 2.
When you put the carb/bowl back on the carb the area below this jet to the bottom of the bowl has to be sealed good when the bowl is installed or gas will bypass this main high speed jet (at the bottom of the bowl) and the engine will run too rich. Make sure this jet and it's passage ways are clear/clean.
This is the High speed gas feed source for the bottom of the emulsion tube.

 

[Forest#2]

Just couple hints. I've never seen that exact carb but couple hints to check.
You need to remove that high speed jet that is in picture 2 and carefully look behind it to see if their are any type of passages other than straight thru.
Most are just straight through to feed the lower portion of the emulsion tube but that one for some reason has a thick casting it screws into.
Some others that jet screws into a thin casting on the side and it has to be removed BEFORE the emulsion tube can be removed on those type carbs.
Also the little slot that is ABOVE the throttle plate needs to be closely inspected and make sure it's not distorted or restricted because as the throttle opens for high speed addition air across it is what draws additional fuel through the H jet up through the emulsion tube.
The upper ring portion of the emulsion tube must seal at it ring to prevent a rich bypass of fuel check the upper portion where the tube fits in the carb's body casting and make sure the lower screw portion is holding the emulsion tube securely seated in the carb body for sealing at each end.
You have to be careful removing that jet and also re-installing. Some require a good snug fitting Hollow ground screwdriver to keep from distorting or breaking the side and also be careful re-installing and not cross thread. some have a slight taper thread and do not re-start easily and some will also get snug before they bottom so keep a heads up about such.

 

[Wurzel]

Just couple hints. I've never seen that exact carb but couple hints to check.
You need to remove that high speed jet that is in picture 2 and carefully look behind it to see if their are any type of passages other than straight thru.
Most are just straight through to feed the lower portion of the emulsion tube but that one for some reason has a thick casting it screws into.
Some others that jet screws into a thin casting on the side and it has to be removed BEFORE the emulsion tube can be removed on those type carbs.
Also the little slot that is ABOVE the throttle plate needs to be closely inspected and make sure it's not distorted or restricted because as the throttle opens for high speed addition air across it is what draws additional fuel through the H jet up through the emulsion tube.
The upper ring portion of the emulsion tube must seal at it ring to prevent a rich bypass of fuel check the upper portion where the tube fits in the carb's body casting and make sure the lower screw portion is holding the emulsion tube securely seated in the carb body for sealing at each end.
You have to be careful removing that jet and also re-installing. Some require a good snug fitting Hollow ground screwdriver to keep from distorting or breaking the side and also be careful re-installing and not cross thread. some have a slight taper thread and do not re-start easily and some will also get snug before they bottom so keep a heads up about such.

I've removed that jet numerous times and checked clear, but maybe there's some type of restrictive build up I've missed. I think it is just the straight passage from memory, but I'll check; also emulsion tube seating.

Boiled carb and back on, temporary fuel supply didn't change the condition.

Spraying a mist of fuel into the carb did allow it to rev when it started stumbling at the usual 50 - 75% revs.

Time is precious and this has used too much of everyones, so meanwhile I'm seeing if I can find a returnable Chinese carb from Amazon in the hope it fits and works.

 

[Forest#2]

Symptoms of starving for fuel.