the 6.75hp craftsman mower (briggs and stratton engine, of course) i bought for $90 4.5 summers ago finally bit the dust and so i picked up a 6.5hp craftsman with b&s "intek" engine (which might have been a bad idea as the reviews are mixed on this particular design) for $50 because it had a cracked and leaking fuel tank

anyway, i requested that it be cold so i could start it up and listen to it run and the guy had complied...it started with just a pull or two, ran smoothly, etc

i started mowing today (about a half acre all said and done) and about 75% through it got suddenly louder and i stopped it...i haven't been able to get it started again

while it had it stopped, i went ahead and switched gas tanks (the old fit the new body just fine) and checked things like the plugs and air filter...when i had it together but the air filter off, i primed the tank on a whim and noticed that gasoline was dripping from the airbox whenever i'd press the bulb...it does the same thing (though to a lesser degree) when the box and filter are back on

also, in case it matters, it doesn't feel like it's actually priming...i assume it's supposed to be pulling fuel into the carburetor, but instead it just seems to be blowing bubbles in the tank (or that's what it sounds like)

thoughts? the guy might have swindled me somehow, but it worked fine for an hour and i thought something might have come loose, broken, whatever...i'm not a mechanic by any stretch of the imagination, but i'm comfortable taking it apart since it's all pretty accessible...i can also get y'all pictures or find a diagram if it will help (the model is 917.378840, in case it matters)

7/15/2012 6:25:36 PM

Umm pinhole in fuel line

7/15/2012 7:37:04 PM

Did you hook the primer bulb up backward?

7/15/2012 11:37:32 PM

- hole in primer bulb
- reversed fuel lines
- bad fuel lines



verify and come back with data

7/16/2012 7:49:47 AM

Quote :

"Umm pinhole in fuel line"

unless it was a large hole, wouldn't it still work? or would it cause a drop in pressure? i think it's a gravity fuel system, not pressurized (though i barely know what i'm talking about, so i could be wrong)

Quote :

"Did you hook the primer bulb up backward?"

i never took it out/apart, so if it's backwards it was like that before (and you'd think it wouldn't have started before)

i forgot to mention that it ran out of gas (because at the time i could only fill it halfway or it would leak and half a tank isn't enough to mow everything) and i primed it after refueling...and got a fair amount of gas on my finger from using the bulb (like it came out of the "nipple" on the bulb)

Quote :

"- hole in primer bulb - reversed fuel lines - bad fuel lines"

the primer bulb already has a hole in it (both of my mowers have)...it's at the very tip and the bulb look like a boob

i don't think the fuel line can be reversed (or it doesn't matter)...like i said above, i think it's a gravity system, so it's just a line that runs from the bottom of the gas tank to...the carb? flipping it around would make any difference

i can't find any leaks in the fuel line itself...nor where it clips to the two nipples (one on the fuel tank and on the other end)...the clips are solid and no holes/cracks in the tube that i can find

7/16/2012 8:15:57 AM

double-checked at lunch...no obvious leaks

if you look at the engine from the front, the air filter is on the left, the bulb is in the middle, and the carb is on the right...priming causes fuel to leak out of the airbox (not just underneath)

7/16/2012 1:15:15 PM

any other thoughts for when i tear it down this afternoon? things to look for (other than what's been mentioned and i've tentatively ruled out)?

7/17/2012 1:03:31 PM

took apart the carb, sprayed it out with carb cleaner, used a bread tie (stripped of plastic, obviously) to poke through the jets/holes in the carb...put it back together and still nothing

it would catch and turn on for a second or two and then spit and cut out...still leaking fuel through the air box, so i'm inclined to believe that the float is stuck (despite being cleaned with carb cleaner)

hole in the float? something else? i'm sure i could buy a new carb, but i don't know if i want to throw money at it anymore...is it a bad idea to use the float from the old mower on the new one?

my yard is looking pretty overgrown and i need to mow it

[Edited on July 29, 2012 at 9:00 PM. Reason : .]

7/29/2012 8:53:11 PM

don't ever use wires and stuff to clean out jets and such. carb cleaner and compressed air are all you should need. sometimes i'll use a piece of straw out of a broom.

[Edited on July 29, 2012 at 9:29 PM. Reason : did you pull the bowl off and clean the needle valve?]

7/29/2012 9:29:01 PM

a couple of youtube videos told me to use a wire...oops

yep, cleaned the needle valve

7/30/2012 6:35:02 AM

...i was thinking 2-stroke on my original statement (they are closed-circuit, so to speak, with the fuel tank)


How does the spark plug look>?

7/30/2012 7:28:32 AM

spark plug looks pretty good...used, sure, but relatively clean and the center is in good shape...verified the gap when this first started

7/30/2012 7:49:12 AM

sounds like the needle seat is torn cracked or loose

7/30/2012 4:02:11 PM

i'll try replacing the existing float and needle this afternoon

7/30/2012 4:14:32 PM

the float also has to be adjusted correctly. if it has a metal arm it can get bent, or may need to be adjusted. probably plastic though.

7/30/2012 5:09:15 PM

the entire float is plastic...looks almost exactly like the picture below, but the two floats i have (which are identical in every other way) are yellow and orange



not sure what else to do...i took it apart again at lunch, cleaned it with carb cleaner again, put it back together...it will catch briefly and then die

i just need to mow the jungle that is my front and back yard

7/31/2012 1:05:41 PM

pour a tablespoon of gas down in the carburetor and see if it'll run

7/31/2012 10:27:25 PM

it runs for a second or two and quits

i removed the air filter to spray some starter fluid down in there and noticed that it's STILL leaking fuel when i prime it...which, i assume, still means that float is getting stuck open

i suppose i could get a carb rebuild kit, but i'm not sure it's worth the $20

8/1/2012 8:32:00 AM

get it started and push the primer bulb while it is running and see if that keeps it running. If that is the case it is your fuel pump. When you took apart the carb, did you pull the float needle and inspect it as well as clean out the passage with carb cleaner and compressed air? One way to tell if the needle is seated correctly is to take the upper half of the carb, push the float all the way up (to seat the needle) and blow into the fuel inlet. You should not be able to blow through it since the needle should be seated and sealing the passage. If it does seal correctly then you need to adjust the metal arm on the float. Pm me if you have any questions, these carbs are pretty simple

tl, dr bad float needle or misadjusted float

[Edited on August 1, 2012 at 8:54 AM. Reason : ^]

8/1/2012 8:53:55 AM

Quote :

"get it started and push the primer bulb while it is running and see if that keeps it running."

i overstated by saying it runs a second...it almost never actually catches and when it does, it's more like a half-second or something...i'll try, though

Quote :

"If that is the case it is your fuel pump."

this is probably a dumb question on my part, but...does a gravity-fed carbureted fuel system HAVE a fuel pump?

Quote :

"When you took apart the carb, did you pull the float needle and inspect it as well as clean out the passage with carb cleaner and compressed air?"

yes...though unless it was something obvious like a gouge or worn spot on the needle, i'm not sure what to look for

Quote :

"One way to tell if the needle is seated correctly is to take the upper half of the carb, push the float all the way up (to seat the needle) and blow into the fuel inlet. You should not be able to blow through it since the needle should be seated and sealing the passage. If it does seal correctly then you need to adjust the metal arm on the float."

good idea...i'll try that

Quote :

"Pm me if you have any questions, carbs are pretty simple"

you might very well have a green inbox after lunch or later this afternoon

8/1/2012 9:11:28 AM

Quote :

"this is probably a dumb question on my part, but...does a gravity-fed carbureted fuel system HAVE a fuel pump?"

sorry, didnt realize it was gravity fed. Did you replace the fuel lines? Real cheap and easy to do.

8/1/2012 10:40:48 AM