21 hp Vangaurd loses power when hot

kbdogmanJune 28, 2010

Vangaurd 21 hp #385777 / 0349E1 / 04012811

Starts easily and runs strong for about 5 minutes. It will suddenly lose power and sound as though the motor is struggling. Turn off the blades and sounds like it is running fine. Not smoking. I have searched the forums and done the following:

1. Checked all pulleys on deck

2. Cleaned carb with compressed air

3. Re-set the valves

4. Checked fuel flow

I can't visually see anything wrong with the valves or rods. The engine has about 300 hours on it and has been well maintained with oil and filter changes.

I read on one of the post about 2 coils and maybe one going bad, but I can't even find a coil, maybe does not apply to this engine?

Any ideas would be greatly appreciated and thanks in advance for your help

Ken Bradley

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First, pull engine shroud sheet metal, clean fins and chk for any hidden wire damage.
then next time if it still cuts up, stop and check right away for spark to both plugs.If you are still getting a nice hot spark to both plugs, may still have a fuel delivery prob. that could mean checking the entire fuel line back to tank, replacing any soft/cracked lines, new fuel filter, gas cap vent cleaned and possibly another serious carb cleaning along with draining all old fuel outta the tank and replacing with fresh...

And mebbe Walt will drop by with some of his sage advice..

    Bookmark   June 28, 2010 at 11:45AM
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Ditto on cleaning the gas cap vent hole. Often is the cause of problems fitting this description.

    Bookmark   June 28, 2010 at 1:33PM
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"I read on one of the post about 2 coils and maybe one going bad, but I can't even find a coil, maybe does not apply to this engine?"

Coils located under cooling shroud.

Walt Conner

    Bookmark   June 28, 2010 at 2:07PM
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Thanks for the replies.

Forgot to say I cleaned all of cooling fins, new fuel filter, gas cap vent is OK. I will check the spark and fuel lines all the way back to the tank. I have been through the carb 2 times.

Could it be an oil problem? Maybe oil pump bad?

Will look for the coils this afternoon and post back tomorrow.

Thanks again.

    Bookmark   June 28, 2010 at 2:33PM
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do you still have spark when engine stalls ?

    Bookmark   June 28, 2010 at 2:56PM
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Checked spark and it was good. Blew out fuel lines with air to make sure they were clear. The lines looked good. It ran about an hour as opposed to the 5 minutes the last 5 or 6 times.

So it is a fuel delivery problem. I can't see down in the tank, but I suspect there is some trash in the tank. Tomorrow I'll clean out the tank, fuel lines up to the filter. . I think that will get me going again.

Thanks again for the help.

Ken Bradley

    Bookmark   June 29, 2010 at 10:26PM
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macx(6a SE Missouri)

Had a similar problem with a 16 hp V twin Vanguard.
Removed the carb fuel bowl (easiest to remove th carb
first) and found small particles in the fuel solenoid
valve in the bottom of th bowl - part of the assembly
that holds the fuel bowl on to the carb. Just be real
careful about removing the bowl and the gasket (or O ring,
can't remember for sure) without damaging it and it can
be reused. I think it's an O ring and it fits into a groove.

    Bookmark   June 30, 2010 at 11:58AM
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