lawn mower starts... then dies

websthes · #1 (**permalink**) 07-02-2009, 05:23 PM

first thing I noticed is the primer... it seems to be sucking more air than gas... but when i peek in the carb, i can see the gas squirting in there, and after priming it like 20-30 times, the engine will start, but it dies after a few seconds.

I removed the fuel tank, then removed the fuel bowl off the bottom of the carb.. there was gas in there, the little plastic float moves just fine.

I tried blowing thru the hose that delivers the fuel to the carb but I can't. So I'm guessing there's something jammed up in the carb... am I guessing right?

hoosierbaby64 · #2 (**permalink**) 07-02-2009, 05:51 PM

Mine was kinda acting like that and it was water in the fuel. So a guests dumped some rubbing alcohol in and it stayed running. But since you cant blow thru the tube I would guess there is an issue there. I am no mechanic but I hope you get the problem solved.

You may also want to make sure you don't have diesel in it instead of gas.

jim henderson · #3 (**permalink**) 07-02-2009, 06:00 PM

If it has been sitting a long time it may have gummed up or varnished the jets in the carb.

My generator often does this if I let it sit, especially if the gas in the carb dries out.

If you are handy in the garage, most carbs are pretty easy to disassemble and clean. becareful about damaging gaskets so you can reuse them.

Usually I find that the jet and or needle valve inside the float bowl are the most likely culprits to clog up.

Carb cleaner and some fine drill bits to poke out gunk are usually all it takes.

To prevent clogging I empty the tank and run the engine til it dies.

Good Luck,

Jim Henderson.

Action4478 · #4 (**permalink**) 07-02-2009, 06:04 PM

Quote:

Originally Posted by websthes

first thing I noticed is the primer... it seems to be sucking more air than gas... but when i peek in the carb, i can see the gas squirting in there, and after priming it like 20-30 times, the engine will start, but it dies after a few seconds.

I removed the fuel tank, then removed the fuel bowl off the bottom of the carb.. there was gas in there, the little plastic float moves just fine.

I tried blowing thru the hose that delivers the fuel to the carb but I can't. So I'm guessing there's something jammed up in the carb... am I guessing right?

\Most likely some junk in the jets ,,may need a good cleaning ....

websthes · #5 (**permalink**) 07-02-2009, 06:07 PM

I have the carb off.. there's a big o-ring where it sends the fuel to the motor, and I took the gasket off as best I could.

Can I just soak the whole thing in some parts cleaner?

mercman86 · #6 (**permalink**) 07-03-2009, 12:08 AM

If you are gonna soak the entire carb in parts cleaner, make sure you remove any plastic or rubber componets off of it. They will get damaged by the solvent.

daddy172005 · #7 (**permalink**) 07-03-2009, 01:32 AM

What does the air filter look like?

ckal704 · #8 (**permalink**) 07-03-2009, 07:24 AM

Likely possibilities:
1 water in fuel. Will eventually pass, but it is easier to drain the carb and fuel tank and replace with fresh gas
2 clogged fuel line. Kinda uncommon with most newer engines as they have a filter in the tank. Pull fuel line off carb. Drain some fuel. It should exit the fuel line with a stream of fuel that is the same diameter as the fuel line. If it trickles, it is blocked somewhere.
3 blockage in the float needle valve assembly. Pull the bowl. Let the float hang. Fuel should trickle steadily and somewhat rapidly.
4 blockage in the pickup tube. Careful application of a small drill bit run up through the pickup tube will clear it.

Running and stopping is a clear indication of lack of fuel. If you have to prime it that much to get it to fire, I am betting there was some water in the bowl. Or your primer bulb might have a tear. Can you see the fuel shoot up the p/u tube when you push the primer? If so, bulb is ok. Lots of fuel shooting into the carb barrel but still hard to start? Probably old fuel or has water in in.
You don't say what kind of engine, but there are tons of carb pictures etc. online.

websthes · #9 (**permalink**) 07-03-2009, 10:48 AM

It's a sears Craftsman... think it's a briggs and stratton engine but the sticker's washed off.

I put it in a jar with some parts cleaner last night. This morning I put the fuel line back on and was able to blow some air thru so I guess I cleared out whatever was blocking it up.

Does anyone know a site with pictures of how to put this thing back together?

rangerfan · #10 (**permalink**) 07-03-2009, 10:58 AM

Mine did the same thing as yours did earlier in the year. I ended up putting a manual choke on it. The automatic choke was shot.

websthes · #11 (**permalink**) 07-03-2009, 06:03 PM

Well got it back together.. have one little bolt left over but it runs good now.

guthrie&co · #12 (**permalink**) 07-05-2009, 08:34 AM

sometimes it is cheaper just to buy a new carb

tcbofade · #13 (**permalink**) 07-05-2009, 03:08 PM

Quote:

Originally Posted by websthes

Well got it back together.. have one little bolt left over but it runs good now.

...no job is finished unless you have some parts left over!

Glad that it's running!

websthes · #14 (**permalink**) 07-05-2009, 05:13 PM

Getting the carb off was more trouble than anything... I used some degreaser from Canadian Tire, the guy said it doesn't damage the rubber but it cleared the gunk out of there.

Flexfuel-Dave · #15 (**permalink**) 07-06-2009, 02:18 PM

My mower did the same thing earlier this year. It would start then die shortly after. It's a 10-year old Craftsman 5 1/2hp mulcher.

The gas and flow was good. It turned out that my spark plug was way out of gap.

After regapping it to the magic .040", it runs like like an angry woodchuck!