briggs 5 h.p. 206 cc engine. Runs on ether but not gasoline, even when gas is put in carb or spark plug hole. Gas is good, spark good, muffler clear, valves work, crankshaft key good, not flooded, every known thing is ok but won't fire or run on gas no matter how much cranking you do. All I can figured is bad rings & piston. Anything I'm overlooking?
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- Thread starter 2x4
- Start date
720 popper
New User
Turn crank backwards and it should bounce back sharply when it hits the compression stroke. If not you have a compression problem. (rings, valves or gasket leak)
BigMarv1085
Member
Pull the head off and check for stuck valves
Anonymous-0
Well-known Member
Did you try a new spark plug? Is the plug wet after trying to start the engine?
rd 2N in mo
Member
I am having the same problem. Just finished removing the top shroud and removed all the mouse nests and paper stuff.. tried to start with new gas, it starts until the gas burns out , will have to remove the carb and clean it out with carb cleaner. all due to gas varnish in the carb sticking to the interior of carb.
Are you saying it will not fire if you put mabey 2-3 cc of gas directly in the combustion chamber through the plug hole? If that's the case I expect you have a spark problem. If it starts, runs for a couple seconds and quits after priming like that I expect you have a gummed up carb which is pretty common these days.
If it won't start for priming and will only run on sustained bursts of ether I'd wager you have both a spark and fuel problem....
Even an engine with bad rings should run OK when started on ether.
I see a lot of gummed up carbs on some things around here, just from sitting. Prime them once and let it run for an hour and it's good to go again.
As a matter of practice I'd change the plug and prime it, then see what happens.
Rod
If it won't start for priming and will only run on sustained bursts of ether I'd wager you have both a spark and fuel problem....
Even an engine with bad rings should run OK when started on ether.
I see a lot of gummed up carbs on some things around here, just from sitting. Prime them once and let it run for an hour and it's good to go again.
As a matter of practice I'd change the plug and prime it, then see what happens.
Rod
old
Well-known Member
- Location
- Camdenton Missouri
Pull the air cleaner off and hold your hand over the air intake. Try the start it with your hand there. You should get both a good suction and gas on your hand when you do that and it may even try to start.
If this engine has the aluminum key to hold the flywheel to the crankshaft in the correct position, then check it to make sure it has not been deformed or sheared to the point of not firing at the correct time. I have had both happen before. It would still fire the sparkplug, but not quite at the correct moment. Also, the head might need to be pulled to see if there is excessive carbon build up in it that could be holding a valve open. I had that happen also, with a stuck valve that would not quite close all the way. I find it is better to put a little gas in the carburetor than in the plug hole so that it won't flood the engine.
A guy posted a procedure for starting an engine that has sat for some time, and its really worked for me.
Drain gas (even if its "good" gas you just put in); disconnect fuel line at the bottom of the tank; spray carburetor cleaner into the fuel line that you just disconnected; spray carb cleaner into the throat of the carburetor; reconnect fuel line to tank; and finally, spray some more carb cleaner into the empty fuel tank.
Not only has this worked 3 out of 3 times for me, but all 3 have started on the first pull. Sure would recommend this before removing carb and fooling around with it. For some reason, that just never seems to work out well for me.
Drain gas (even if its "good" gas you just put in); disconnect fuel line at the bottom of the tank; spray carburetor cleaner into the fuel line that you just disconnected; spray carb cleaner into the throat of the carburetor; reconnect fuel line to tank; and finally, spray some more carb cleaner into the empty fuel tank.
Not only has this worked 3 out of 3 times for me, but all 3 have started on the first pull. Sure would recommend this before removing carb and fooling around with it. For some reason, that just never seems to work out well for me.
It amazes me how people will try to give advice and it seems they have not read or understood your note! When I have had a similar problem it usually is plugged passageways in the carburetor, might clean out with carb spray without disassembly, or you might have to take it apart. On some you can just remove the bowl and clean out the passageways in the jet tower, leave the carb attached to the engine.
ShadetreeRet
Well-known Member
Does it have a float type carb. or is the carb on top of the tank? 5hp likely has the float type, but if the carb. is on top of the tank, chances are the fuel pump diaphragm is bad. Just a thought.
your simply not getting any fuel to engine most likely.you do know they nearly all have a fuel pump dont you?a whopping $3 at ace hardware(bought one this weekend) for the most common one, so probably $1 at a lawn mower shop.Replace the fuel pump,its just a sheet of rubber generally,and pull the pickup tube out of your tank and clean the screen on the bottom of BOTH.AND!!! Fill your fuel tank COMPLETLY full,believe it or not,most of the engines with built on tank do not suck fuel directly from tank,it has a seperate resivoir that the fuel pump keeps filled and it sucks fuel from there to engine,to keep fuel level constant( this is why starting instructions say to check oil,AND FILL tank!not simply check fuel).fuel pump needs vacumn off running engine to operate real well,at slow cranking speeds they often cant suck enough fuel.this is really bad if you have a electric start and battery is low from setting all winter.IF you have a weak pump,filling your tank completly full,fills this.then if your fuel pump is bad it will often run until empty and die.AND go ahead and change the plug,ether enriches fuel mixture making it easier to ignite,lawn mower shops make a fortune off changing plugs every year! my cousin made his living at it for a long time.
Sounds strange...
I guess if you've got a compression tester it wouldn't hurt to check and see what it's got with the throttle and choke fully open. I'd think it should make 100 psi or so.
Beyond that I'd wonder about spark timing provided you give it a good slug of gas in the plug hole...
Rod
I guess if you've got a compression tester it wouldn't hurt to check and see what it's got with the throttle and choke fully open. I'd think it should make 100 psi or so.
Beyond that I'd wonder about spark timing provided you give it a good slug of gas in the plug hole...
Rod
Anonymous-0
Well-known Member
I believe Rod is on the right track.
Although it is not common, I have seen engines that acted the same as yours.
If you tested for spark across the sparkplug gap, in open air, that does NOT mean the ignition is good!
The spark must be able to jump a gap of 1/4" or larger to be a considered a "good" spark. ....A blue spark is better than an orange or yellow spark, but if it will jump a 1/4" gap, the color doesn't really matter.
Hold the plug wire terminal approx 1/4" away from a good (not painted) ground on the engine while cranking. ....If the spark jumps that distance, then I would rule out ignition, although the ignition TIMING may be wrong.
A sparkplug must fire during compression, and it takes more electrical energy to jump a gap, than when it is firing in open air. ....A weak spark will jump the plug's gap in open air, but may not be strong enough to fire under compression.
Another good way to test the intensity of the spark is to place a SMALL amount of gasoline on the surface of the cylinder head, and hold the terminal of the sparkplug wire away from the surface approx 3/16". ...Crank the engine to see if the spark will ignite the gasoline.
If the spark does not ignite the gasoline, the spark is not strong enough, or you are trying to burn water. (I have seen both scenarios many times!)
Although it is not common, I have seen engines that acted the same as yours.
If you tested for spark across the sparkplug gap, in open air, that does NOT mean the ignition is good!
The spark must be able to jump a gap of 1/4" or larger to be a considered a "good" spark. ....A blue spark is better than an orange or yellow spark, but if it will jump a 1/4" gap, the color doesn't really matter.
Hold the plug wire terminal approx 1/4" away from a good (not painted) ground on the engine while cranking. ....If the spark jumps that distance, then I would rule out ignition, although the ignition TIMING may be wrong.
A sparkplug must fire during compression, and it takes more electrical energy to jump a gap, than when it is firing in open air. ....A weak spark will jump the plug's gap in open air, but may not be strong enough to fire under compression.
Another good way to test the intensity of the spark is to place a SMALL amount of gasoline on the surface of the cylinder head, and hold the terminal of the sparkplug wire away from the surface approx 3/16". ...Crank the engine to see if the spark will ignite the gasoline.
If the spark does not ignite the gasoline, the spark is not strong enough, or you are trying to burn water. (I have seen both scenarios many times!)
huntingreen2day2
Member
Blow in the gas tank and see if you can blow fuel up into the carb. Just don.t do this on a racing go kart like I did. Wound up chasing it across the parking lot. The bounce back method on the flywheel is Briggs recommended way to test the compression. I assume this is a flat head engine. Replace the rubber diaphram (sp) if you have not. There are 2 real small holes in the carb body. With the butterfly closes the smaller hole is on the engine side. This is the slow speed hole. the larger hole is in the rear side of the butterfly. Make sure these are open. Either of the pick up tubes could be stopped up. The long tube picks up the fuel from the tank. The short tube picks up fuel from the upper part of the tank.
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