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A21A42 lawn tractor with 21hp briggs &Stratton engine

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A21A42 lawn tractor with...

A21A42 lawn tractor with 21hp briggs &Stratton engine number(###) ###-####G1. I have replaced the battery and the starter and checked the selenoid. When I try to start it doesn't have enough power to rotate the engine. But, if I remove the spark plug, thus eliminating compression, it turns over freely but of course wont start without the sparkplug. Any ideas?

Mechanic's Assistant: Do you have fuel in the tank? If so, is the shut-off valve open and the fuel clean?

Yes and there is air in the tires

Mechanic's Assistant: Do you plan on doing the work yourself?

Yes

Mechanic's Assistant: Anything else we should know to help you best?

Did you read what I already sent?

Submitted: 11 months ago.Category: Small Engine
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Answered in 9 minutes by:
9/12/2017
Technician: Curtis B., Technician replied 11 months ago
Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 15,342
Experience: have worked on and around most engine models for 35 yrs./Polaris ATV expert
Verified

Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!

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Technician: Curtis B., Technician replied 11 months ago

The engine has a compression release as part of the camshaft gear. If it breaks, the compression is too high for crank. Run compression test and if over 100 psi, the compression release is broken,, and repair is to replace the camshaft.

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Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

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