Briggs 18.5HP Cranks Slow

[darrinster]

Model: 31P777-0299-E1

Just picked this mower up. Crank case was full of gas. Drained out the gas, put in new oil. Adjusted the valves. Engine cranks slow. Tried another starter, same thing. Tried jumper cables directly to do the starter and no change.

Then I put my hand over the intake that is connected to the carburetor and it started spinning fast and started. Runs really good. Still wont spin fast unless I hold my hand over the intake.

Really stumped here.

 

[mechanic mark]

http://bsintek.basco.com/BriggsDocumentDisplay/29nuAJYUogC_Fix2.pdf

You still have gas in crankcase, carburetor problem. You will need code number from engine for locating correct carburetor overhaul kit or new carburetor, google B&S part number & search for best price. Remember to change oil.

 

[darrinster]

http://bsintek.basco.com/BriggsDocumentDisplay/29nuAJYUogC_Fix2.pdf

You still have gas in crankcase, carburetor problem. You will need code number from engine for locating correct carburetor overhaul kit or new carburetor, google B&S part number & search for best price. Remember to change oil.

Finally got it to crank without holding my hand over the intake. Going to change the oil again after I get the carburetor cleaned.

 

[Tinkerer200]

You need to add a gas line shut off valve and use it when the engine is not running. There is a good chance the float needle will continue to leak even after you change needle and seat. Also, IF the engine is equipped with a fuel pump, the diaphragm may be ruptured letting fuel leak.

Walt Conner

 

[darrinster]

You need to add a gas line shut off valve and use it when the engine is not running. There is a good chance the float needle will continue to leak even after you change needle and seat. Also, IF the engine is equipped with a fuel pump, the diaphragm may be ruptured letting fuel leak.

Walt Conner

Not so good news. Engine has a knock.

 

[tackleberry]

Model: 31P777-0299-E1

Just picked this mower up. Crank case was full of gas. Drained out the gas, put in new oil. Adjusted the valves. Engine cranks slow. Tried another starter, same thing. Tried jumper cables directly to do the starter and no change.

Then I put my hand over the intake that is connected to the carburetor and it started spinning fast and started. Runs really good. Still wont spin fast unless I hold my hand over the intake.

Really stumped here.

 

[slomo]

ACR or auto compression release has failed. New cam time. Easy repair.

 

[tackleberry]

Likely you've got a bad compression release on your cam. You also have a leakey Carb float not shutting off (or your backfire solenoid is not working on your float bowl, which is supposed to shut off fuel when you turn off your key. You can test that by turn the key on, you should be able to hear the solenoid click). Multimeter the wire to the solenoid and look for 12 volts DC when the key is on..if you have power but no click, your solenoid could be frozen (it should retract when you turn on your key and extend when off to seal your main jet)
Either way, install a fuel shut off so that you can shut off the fuel when you shut down your engine. Your Knock may be pieces of the compression relief spring and pin floating around in your crank case. Starting with your hand over the intake relieves some of the compression pressure and it will spin and that is indicative of a bad cam and compression relief. It will require internal work and replacement of the cam. My advice, its very doable yourself, with care. Many youtube videos on it..chickanic has a very good video. Go with OEM B&S part only for the cam and sump gasket and oil seal...the aftermarket ones are iffy. If you farm it out look for $200 smackers or more and backlog.

 

[VegetiveSteam]

Many of us have either done it come close to doing it but just FYI, you're responding to a 7 year old post.

 

[slomo]

Many of us have either done it come close to doing it but just FYI, you're responding to a 7 year old post.

Time limit police. Helpful post is a helpful post.

Most mowers are several years old as well.