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View Full Version : 4.0 B&S Quattro runs rich


evan price
05-19-2005, 01:21 PM
Brand new push mower with B&S 4.0 Quattro (Looks like a Classic, which is a 9200 series of 30 year old vintage!)
Runs real rich, smokes black, sputters, stalls, revs back up, will sorta run, but it just floods out, plug is black carboned up. I swapped another known good carb & gas tank and does the same thing.

evan price
05-19-2005, 04:17 PM
Forgot to mention- in the old days this carb had an adjustment needle, now it's plastic and no adjustments, this is a trim mower, a cheapy, not gonna spend much money on it. Gas is clean and fresh, took carb off of tank and cleaned screen & pickup tube, pulsator spring is on diaphraghm where it should be, saw no holes in diaphraghm. Air filter on/off no difference (it's clean and not too oily), and I put the air filter screw in the hole with it off to be sure, & no difference.
It runs so rich it flood itself out tries to stall, then restarts itself as it is spinning to a stop.
If you push the handle down so deck is about 45 degree angle, after a few seconds it starts running right but then 20-30 seconds later it runs out of gas (due to no fuel on pickup maybe) and stalls.

The replacement carb I put on came from a good running similar model motor (B&S Classic 3.5 hp) that a guy ran over a sprinkler head and bent the crank so I know motor ran fine (but shook like hell) I just swapped the carb onto the newer tank to put on the new trim mower.

Do you have to spend $400 to get a decent trim mower any more??? These $150 push mowers used to be great & that 92000 was once a great motor.

Restrorob
05-19-2005, 06:45 PM
Forgot to mention- in the old days this carb had an adjustment needle, now it's plastic and no adjustments, this is a trim mower, a cheapy, not gonna spend much money on it. Gas is clean and fresh, took carb off of tank and cleaned screen & pickup tube, pulsator spring is on diaphraghm where it should be, saw no holes in diaphraghm. Air filter on/off no difference (it's clean and not too oily), and I put the air filter screw in the hole with it off to be sure, & no difference.
It runs so rich it flood itself out tries to stall, then restarts itself as it is spinning to a stop.
If you push the handle down so deck is about 45 degree angle, after a few seconds it starts running right but then 20-30 seconds later it runs out of gas (due to no fuel on pickup maybe) and stalls.

The replacement carb I put on came from a good running similar model motor (B&S Classic 3.5 hp) that a guy ran over a sprinkler head and bent the crank so I know motor ran fine (but shook like hell) I just swapped the carb onto the newer tank to put on the new trim mower.

Do you have to spend $400 to get a decent trim mower any more??? These $150 push mowers used to be great & that 92000 was once a great motor.


If this unit still runs the same with a known good carb. I would check the flywheel key,It could be sheard enough to run but fire out of time.

barnard
05-19-2005, 11:33 PM
It's the gasket and diaphragm between the carb and tank if it's not just right it suck in raw gas . usually the diaphragm shrinks and doesn't seal .

Restrorob
05-20-2005, 08:04 AM
It's the gasket and diaphragm between the carb and tank if it's not just right it suck in raw gas . usually the diaphragm shrinks and doesn't seal .

The diaphragm is a fuel pump,It pulls the fuel up from the tank and delivers it to the small reservoir in the top of the tank where the carb. main jet picks it up to run.A bad diaphragm will cause a lack of fuel to the reservoir which in turn will cause a no start or hard start and lean run (hunt) situation.
I don't remember ever seeing one cause a rich run condition.

barnard
05-20-2005, 09:38 PM
I've seen it three times. The diarphram will shrink in an area that lets the suction (that normally moves the diaphragm) suck fuel from under the diaphragm past the edge where there is not a good seal .Trust me i've fixed three with this condition.

Restrorob
05-20-2005, 11:42 PM
I've seen it three times. The diarphram will shrink in an area that lets the suction (that normally moves the diaphragm) suck fuel from under the diaphragm past the edge where there is not a good seal .Trust me i've fixed three with this condition.

I'm not doubting at all,I just didn't remember seeing this.
After being burned on a couple jobs on 129.00 on sale 99.00 walk behinds the customers oked repairs and never picked up,I don't even let them unload I send them down the road. I only work on the high end self-propell and they have to be in good shape or they go down the road too. I have plenty L/Ts ,
G/Ts and Commercial Equipment to keep me busy.