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First time posting. I mounted a 212cc, 6.5HP Predator engine on a vintage Mighty Mac Shredder/Composter. Original engine was likely in the 3 HP range, I believe.
The engine starts up fine from cold, sits and runs at least 5 min OK but when I engage the belt drive, even before putting in compost, the engine runs for 1/2 min to 3 or 4 min but then shuts down sounding exactly as if running out of fuel but bowl is full. Then won't start until the engine sits for 10-15 min. Fuel flow from tank more than sufficient to keep up with needs. Tank full, have pulled carb and cleaned thoroughly several times. The float level is not adjustable. Fuel is clean & fresh. No direct access to the vent in the cap tho have tried to be sure it's open with comp air and carb clean spray as best I could. (Have same result if I run with the fuel cap completely removed.) Spark plug looks OK, slightly dark but engine never ran long enough to heat up and burn clean. Not so dark as to fire bad tho. Good wide spark although more to the yellowish color than bright blue/white.

When the engine does run, it sounds good and strong and when cold it starts up easily with a light pull.

Any ideas are appreciated or if I am in the wrong forum please advise if there is a more suitable forum.

Thank you so much.

DH

Check for spark when it shuts down.

Got a half quart of oil in it?

I would put in a new sparkplug. The chineese plugs are notorious for being bad out of the box. I have not had much luck with any of the chineese plugs.

Hammermechanicman said:

I would put in a new sparkplug. The chineese plugs are notorious for being bad out of the box. I have not had much luck with any of the chineese plugs.

Click to expand...

Good advice... Predator's come with a "Torch" brand..

I go for a NGK BPR6ES OR BPR5ES in the predators

I am with Star on this
Get yourself a red in line plug tester, fit it and start the engine.
Watch the flashes
When running you should see a continious orange glow from the tube
If it stays like that till after the engine starts to miss and continues to flash right to the bitter end then you have a fuel problem
If fitting the tester "solves" your problem you have the wrong spark gap ( too small ) or wrong type ( non resistor ) plug fitted.
As the engine is dieing squirt some carb cleaned down the carb throat
Makes no difference then look at the timing key and valve lash
Runs fine then the fuel supply is insufficient
You can double check this by applying the choke very slowly
Engine runs bettee = restriction in the fuel supply
engine runs worse = excess fuel, main jet enlarged, or missing

suzukizone said:

First time posting. I mounted a 212cc, 6.5HP Predator engine on a vintage Mighty Mac Shredder/Composter. Original engine was likely in the 3 HP range, I believe.
The engine starts up fine from cold, sits and runs at least 5 min OK but when I engage the belt drive, even before putting in compost, the engine runs for 1/2 min to 3 or 4 min but then shuts down sounding exactly as if running out of fuel but bowl is full. Then won't start until the engine sits for 10-15 min. Fuel flow from tank more than sufficient to keep up with needs. Tank full, have pulled carb and cleaned thoroughly several times. The float level is not adjustable. Fuel is clean & fresh. No direct access to the vent in the cap tho have tried to be sure it's open with comp air and carb clean spray as best I could. (Have same result if I run with the fuel cap completely removed.) Spark plug looks OK, slightly dark but engine never ran long enough to heat up and burn clean. Not so dark as to fire bad tho. Good wide spark although more to the yellowish color than bright blue/white.

When the engine does run, it sounds good and strong and when cold it starts up easily with a light pull.

Any ideas are appreciated or if I am in the wrong forum please advise if there is a more suitable forum.

Thank you so much.

DH

Click to expand...

If it sounds "exactly as if it ran out of fuel," that's probably what it did.

When warming up, even at fairly high speed, the engine isn't using a lot of fuel. So the problem could still be with fuel supply.

One way to find out would be to remove the air cleaner. Start the engine, warm it up and apply the load. When it starts to die, give it a shot of starting fluid. If it speeds back up, it is definitely a fuel supply problem.

One other thing I've experienced that is somewhat like this--does it have a 'low oil' shutdown? I have a Tecumseh powered generator that exhibits these same symptoms, IF the oil is slightly low.

Thank you all for these tips. I am actually going to paraphrase and print them up and keep in the garage with the manual.

I have been having better success with the engine. Other than tying to figure its quirks relating to starting some times, it has been running steadily. I do warm it up on idle speed for about 3 or 4 min then on full throttle for anohter 1 or 2 min. Then turn off & hook up the belt drive. Occasionally it may be reluctant to restart but when it starts up, I have been able to run branches & yard debris for up to 20 min or so at a time. At that point I turn it off to go load up the garden trailer with more yard junk to run through. Not sure what made it decide to cooperate but I will be getting a new NGK plug tomorrow as I am thinking that might be a good chunk of the proble.

So thanks again. Will post a pic of the rig as soon as I get a chance in this thread.

DH