Tecumseh 6.5 hp runs 10 seconds, dies

[California]

Tecumseh 6.5 hp runs 10 seconds, dies. it's on a Craftsman high-wheel HD string trimmer.

This ran fine when I ran it out of fuel then stored it 5 years ago. Now it fires off like new but runs 5 to 20 seconds before dying. Sounds starved for fuel. I repeated this many times.

I took off the float bowl and checked that the jet? (that holds the bowl in place) wasn't clogged. There was fuel in the bowl.

Clearing that jet, once when new, is the only repair this motor ever needed.

What do I check next? Will the float needle stuck cause what I observed?

Any advice will be appreciated.

 

[bigdeano]

Have you tried adjusting the fuel mixture needle valve? The only other thing I can think of is the condenser might be bad. I had to replace the one on my 1970s Tecumseh 6 HP a few years ago.

 

[TractorGuy]

Ran into this with a Honda powered pressure washer. Replaced carb and coil. Turned out to be the spark plug. New plug and it ran like a top.

 

[Norm W]

Tecumseh is an old native American word for won't work. Pull the bottom of the float bowl off and see what the flow is. It sounds like there is some obstruction in the line from the tank to the float bowl. If it was an ignition problem it wouldn't run at all.

 

[tomplum]

If it sat for 5 years, it will need a new float valve kit. Plus if it has the plastic emulsion tube ( in the carb stem), replace the o rings and bowl seal as well. Or the carb for that matter with an OEM.

 

[dfkrug]

Pull the bottom of the float bowl off and see what the flow is. It sounds like
there is some obstruction in the line from the tank to the float bowl.

Yeah, there is gonna be crap in the bottom of that fuel tank, which impedes the flow of gas. The tank
and fuel line needs to be cleaned out.

 

[California]

Yeah, there is gonna be crap in the bottom of that fuel tank, which impedes the flow of gas. The tank and fuel line needs to be cleaned out.

Well I ran it dry before storage and tried starting moments after refueling, also there was only a tiny stain in the float bowl when I removed that. So I don't think this is a crud in the fuel issue.

After reading what's been posted so far, I'm tending toward looking for a stuck float needle valve as the next step. Remembering back many years I have had that problem on small engines before, and it seems plausible now.

If it's not fixable without paying a shop, this thing is going to Goodwill. I got it from Sears discounted because it was sitting in a puddle of its own leaked oil. Then after the first year it quit with manufacturing crud jammed in the fuel orifices of the brass nut/metering jet under the float bowl. Then the main shaft that the cutting head spins on, froze up and galled so I replaced that. Total maybe 40 hours use before I stored it. The 4 ft rotary mower behind the tractor plus a handheld string trimmer for the edges, have made this unit un-needed.

Photo: it's a year 2001 craftsman #5067 high weed string trimmer. (online photo of this model).

 

[Fuddy1952]

This is so funny as I'm working on one right now. I didn't even check carb since I ordered a new one eBay for $11. I also am replacing some rubber parts and broken throttle lever.
Any part # you need it's on Sears Parts site, exploded view, etc.

 

[California]

This is so funny as I'm working on one right now. I didn't even check carb since I ordered a new one eBay for $11. I also am replacing some rubber parts and broken throttle lever.
Any part # you need it's on Sears Parts site, exploded view, etc.

Wow, small world! Yours and mine are identical. From 2001.

Buying new parts as you are doing would be the right way to approach mine - but I don't have any use for the machine. A friend I offered it to didn't want it. So my efforts will be limited to just tinkering, not a proper tear down and rebuild as I would if I were putting it back in service.

I dropped the float bowl again and checked for a stuck float needle - it's not stuck. Fuel pours out of the lowered needle so there's no fuel restriction anywhere.

It still starts nice. Then after a few seconds running slow, it dies. No fumes so it's not over-rich.

Spark plug was wet but not fouled. (should be dry in this scenario). Ignition failure would make fumes as it dies, no?

It feels like after a few seconds the governor never calls for enough throttle to keep it running. The throttle lever sets how fast it will run in the first moment but doesn't affect the later slowdown.

Maybe the governor? Checking it requires taking off the fuel tank to get the shroud off, and that would likely mean replacing some 17 year old fuel line parts. I'm not going to tear into it that far for a machine I don't have any need for.

Next stop: Goodwill. Let somebody else get it back in service.

 

[TractorGuy]

Should have got the Briggs model. I have one I bought in 2002 with 6hp briggs. Still starts and runs perfect. All I've done is change the oil and air filter every couple of years.

Seriously, I would spend a couple of bucks on a new spark plug before I threw it away. K.I.S.S.