oldnslo
Super Member
Do you have compression? Not sure how old of a 5 HP briggs this but possible it has auto decompression and this is reducing your compression to the point it won't fire.
Briggs 5hp assistance
- Thread starter RitchElbe
- Start date
- Views: 3773
I do not have a gauge...no idea who borrowed it.. what I did do was place my hand XXL size over the piston while head was off and pulled.. it was sucking my palm down.. now that said.. There is good exhaust pressure out of the muffler..and at times I noticed it was blowing pressure back thru the carb. Which got me to thinking timing was off or stuck valve.. yet with the head off and pulling several time over 4 mins.. the timing seemed to be in sync for the intake power and exhaust strokes.. with that said.. I have noticed it was bone dry in the combustion chamber. Which tells me it is not getting gas at all.. so I shot some ether into it... but it has a strong spark. Seems crazy since the night before it was running like a champ
oldnslo
Super Member
If it is blowing back out the carb your intake valve isn't closing at the proper time. Could be auto-decompression or a piece of carbon stuck on the valve seat. Don't take much to prevent vacuum and compression while starting them.
/pine
Super Star Member
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The shaft/flywheel key is the first thing I would check if I had both fuel and spark but no pop...if it's aluminum (or other soft metal which many are to prevent damage) it can be slightly sheared which could also explain what you "felt" (catch hard) when troubleshooting...
stuckmotor
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I've never heard of an engine like that jumping timing but, if you have to go in as far as the timing gears, make sure and see whether the timing marks are lined up BEFORE removing them. It's a mystry to me why you had to put a pipe wrench on the shaft and I would hate for you to reassemble it correctly and solve the problem without knowing what caused it.
Blaneypark
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Had the same problem with an old Briggs. A new shaft/flywheel key and started on the second pull.
5030
Epic Contributor
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One option is, if you cannot get it running is to replace it with a Harbor Freight Predator of the same size. Cheap and reliable. I've always considered Briggs to be a disposamotor anyway.
KubotainNH
Veteran Member
Definitely check the key but a valve not seating is my bet. I'm thinking it got gummed and stuck which is why it was hard to get spinning and now that sticky stuff is keeping it from moving freely. I've had it happen numerous times on a motor that sat. Sometimes the valve moves but not quickly enough to get good compression because of sludge. The first run of the season may have melted the sludge which reformed into glue when cooled off. Been there....
common practice.. unable to get a full turn.. use a pipe wrench to play the shaft back and forth to see if it loosens up any. In this case I could pull the starter rope and get about a quarter pull from it.. thus the pipe wrench it snagged.. done it on several motors that sat for a extend period of years.... and all of those of still running today... this one has chosen to be a challenge
