Briggs L head runs rich no matter what I throw at it.

[slomo]

Good idea on the main jet swap. I tried that first thing but unfortunately, no change. Then I checked the valve clearance. Zero lash on both valves. Good call again. I've been doing this for 12 years and have never seen an L-head that bad. I'm really surprised it doesn't backfire as well. I'm also surprised the customer gave me the go ahead to fix it.

Thanks again
Chad

All non hydraulic valve engines require valve clearance adjustments. L head, scratch your head, OHV or OHC love it. And being an L-head Briggs, most people NEVER think of this for some reason. I just did one of mine, 1989 era Briggs with 0 lash.

slomo

 

[slomo]

New doesn't mean new at times. Chinese carbs are a gamble. Some are okay and some are like yours. Get the OEM carb for it.

If I were a mower repair shop guy, I wouldn't even entertain getting Ebay or Amazon "Gambler Series" mower parts. Wouldn't be worth it to me at all.

Back to your issue. Over rich is carb needle hanging open, dirty air filter or overly large main jet in that order.

Back off topic, clean the combustion chamber free of carbon, set valves to proper specs and clean cylinder cooling fins all the way around the bore. Then fire is up and check for rich burn.

slomo

 

[slomo]

Spitting fuel out of the carb is carb needle sticking open. Pull the dipstick and smell for fuel in the oil.

Like Rivets said, look at the float level. Carb upside down should hold 7PSI of air pressure. Test yours with a hand pump and gauge. Make sure the float is LEVEL to the carb bowl flange. Several youtube videos about it.

slomo

 

[slomo]

slomo

 

[Richie F]

If it spits out the intake the exhaust valve is not opening enough.
Being that the exhaust is not set correctly the engine is getting choked do to lack of air flow.
You have tried more than one carb with the same results so the carb/float level doesn't come into play.

 

[mwshaw]

I don't know the model but if it's a model with the carb mounted to the gas tank, they will suck gas through the missing air cleaner screw hole. Must replace screw to even begin to adjust the carb. Looks like you have tried everything but that. So I though I would throw that in.

 

[slomo]

If it spits out the intake the exhaust valve is not opening enough.
Being that the exhaust is not set correctly the engine is getting choked do to lack of air flow.
You have tried more than one carb with the same results so the carb/float level doesn't come into play.

Yup, I mentioned to set the valves a few posts ago. Give the ol' girl a fighting chance.

slomo

 

[slomo]

I don't know the model but if it's a model with the carb mounted to the gas tank, they will suck gas through the missing air cleaner screw hole. Must replace screw to even begin to adjust the carb. Looks like you have tried everything but that. So I though I would throw that in.

Different carb you are talking about. Good to know, just doesn't apply here. Thanks for sharing anyway. Might help someone else.

slomo

 

[Tommy Mckeown]

Working on a 6hp 128h02 0515 E1. mounted to a DR style trimmer. came in not running and had a trashed carburetor. I replaced the carb, and did a filter oil and plug and new primer bulb at the same time. It fired on the first pull but ran just rich enough to bog but not blow black smoke, and is spitting fuel out of the carb throat.
The following is everything I've checked and thrown at it so far with zero improvement (in no particular order):
-installed 2 other new carburetors
-checked for vacuum leaks (even though it's not a lean condition)
-pulled the plug to read it and it was black, but not terrible.
-checked compression
-over gapped the plug hoping for some more heat
-changed plug again
-adjusted the coil gap
-pulled the muffler to verify not clogged also ran it with no muffler
-checked flywheel key
-verified proper oil level
-checked for spark strength visually

What did I miss? I can't think of anything....

The only way fuel is coming out of the throat is if the float is bad or the needle and seat is not sealing. Before putting the bowl back on verify that it is in fact sealing when you lift the float.

 

[slomo]

The only way fuel is coming out of the throat is if the float is bad or the needle and seat is not sealing. Before putting the bowl back on verify that it is in fact sealing when you lift the float.

Which takes us to the videos I put up on post 13 and 14. Great tip, check the needle and seat prior to starting the engine. But the carb was new???? LOL

slomo