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Briggs 18.5HP Cranks Slow

#1

D

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.


#2

M

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.


#3

D

darrinster

mechanic mark said:
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.
Click to expand...

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


#4

T

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


#5

D

darrinster

Tinkerer200 said:
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
Click to expand...

Not so good news. Engine has a knock.


#6

tackleberry

tackleberry

darrinster said:
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.
Click to expand...


#7

S

slomo

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


#8

tackleberry

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.


#9

V

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.


#10

S

slomo

VegetiveSteam said:
Many of us have either done it come close to doing it but just FYI, you're responding to a 7 year old post.
Click to expand...
Time limit police. Helpful post is a helpful post.

Most mowers are several years old as well.


#11

tackleberry

tackleberry

Well sorry bout that...but i'm fixin to dig into one myself to fix the aforementioned problem on my own mower (a troy bilt Pony) that i paid $50 bucks for...


#12

V

VegetiveSteam

tackleberry said:
Well sorry bout that...but i'm fixin to dig into one myself to fix the aforementioned problem on my own mower (a troy bilt Pony) that i paid $50 bucks for...
Click to expand...
Nothing to be sorry about. I just wanted to point it out because some find it frustrating when they take their time to try and help someone and the OP never posts back whether or not the issue was resolved.


#13

tackleberry

tackleberry

VegetiveSteam said:
Nothing to be sorry about. I just wanted to point it out because some find it frustrating when they take their time to try and help someone and the OP never posts back whether or not the issue was resolved.
Click to expand...
New here but not new to repair of mowers...today I salvaged a crankshaft out of a 9P B&S engine with no compression to donate to a engine with lots of compression but had a bent crank..Never seen one dance like that before! I have a salvage guy who finds them on the street and i repair and flip them and we share the proceeds (if any). If I find one with no compression its usually not worth my time or money (at $30 to $40 dollars for a ring set, Ridiculous!!) to repair those. but they sometimes make great donor engines.


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