Husqvarna model YTA18542-960480067
Briggs and Stratton 33S777-0001-G1
92hrs on meter
sat in a neighbor shed for a long time.
currently engine turns and sputters but would not run, unburnt fume/smoke/ come out of exhaust, occasionally from intake
Electrical- new battery charged, starter good, solenoids wires and grounds have been tested for continuity and resistance.
Spark- plug and coil is old but tested for good spark. Oil- level good, currently old, but very clean from years ago. Compression- flywheel spins with resistance, plug installed.
Valves- valve cover removed, intake.003 exhaust.005, no adjustment needed. Timing- checked when plug and valve cover off, magnet position and TDC seems aligned. Fuel- fuel tank emptied and cleaned, fuel inline clear and new filter, flow is about 400ml/min at carb more than enough. Nikki Carb- bottom solenoid operates freely. auto choke/ manual choke normal. removed carb, throttle plate and chock plate moves freely, Bowl is extremely clean, drained fuel has no water. ran fine wire through all holes found no Blockage.
what to resort the forum before I tear entire thing apart
What else am I missing? I’m going nuts.
Thank you, ANY thoughts are welcomed.
#2
StarTech
Try a known good plug. Just because the plug sparks outside the compression zone doesn't mean it will spark under compression load.
Also pull the blower housing off & remove the kill wire which will isolate a wiring problem
when I have one of these I fit an inline spark tester to check that I am getting a spark every revolution .
The valve lash sounds right but are the vales protruding the same length into the rocker housing they are identical as is the cam lobes .
#4
shadetree#1
Do a leak down test or try checking the compression and let us know what you see????
Fumes and smoke out of exhaust is a hint.
You can do a leak down just injecting about 20-30 psi air into the spark plug hole using a rubber tipped air gun with the engine locked at TDC. Listen for air out the EX, intake or into the oil galley.
Try spraying gumout carb cleaner in the throat of the carb while spinning it over to see if it will run on it.
#6
Fish
Take the valve cover off, and rotate the flywheel by hand, and watch the rocker arms, make sure that the open close their valves at about the same distance. Make sure that one of the cam lobes isn't rounded off.
Also pull the blower housing off & remove the kill wire which will isolate a wiring problem
when I have one of these I fit an inline spark tester to check that I am getting a spark every revolution .
The valve lash sounds right but are the vales protruding the same length into the rocker housing they are identical as is the cam lobes .
Do a leak down test or try checking the compression and let us know what you see????
Fumes and smoke out of exhaust is a hint.
You can do a leak down just injecting about 20-30 psi air into the spark plug hole using a rubber tipped air gun with the engine locked at TDC. Listen for air out the EX, intake or into the oil galley.
thanks, i don’t have a compression gauge at home. But i did shove a rubber tip into the spark plug hole with 40psi, TDC on compression stroke, no Hissing at all.
Take the valve cover off, and rotate the flywheel by hand, and watch the rocker arms, make sure that the open close their valves at about the same distance. Make sure that one of the cam lobes isn't rounded off.
Thanks, they do travel the same distance, and valves seals fairly well on TDC compression stroke. I’ve put everything back now, and I’ll try to start it with some starting fluid, wish Me luck. Taking the engine apart will be my last step If it still won’t run.
#11
shadetree#1
You say: Taking the engine apart will be my last step If it still won’t run.
That is not a good idea.
I just put a really good engine back together that the previous owner took apart because it would not start. I think he mainly just wanted to see what was inside. He had all the parts in a tub and just gave all to me including the tub, said he was sick of it and he bought a replacement engine.
When I got it back together it would not start, not even try to start, had good compression, spark at plug and I primed with gas. No go.
Spark seemed little strange maybe little weak when checked on a spark plug gapped at .050 as a test. Briggs spark tester produced a spark but not blu/white when viewed in dark room
Throwed a $15 Clone magneto on it a instant start.
Do not overlook the simple things. Compression, fuel, ignition (at the correct time)
#12
shadetree#1
You asked:
Blower is off, but what is the kill wire?
The kill wire is the black wire that is connected to the magneto.
Sometimes the small black magneto kill wire is under the magneto (bottom next to engine) and the mag has to be unbolted to disconnect (unplug) at the mag. I sometimes just cut the magneto kill wire by the starter area to keep from having to remove the air cowling, and I strip about 1 inch of insulation from the end for grounding if the engine then starts with the kill wire disconnected. This lets me know if the kill wire is grounded back towards the engine wire harness towards the switch.
When this wire is grounded it kills the engine and spark. Sometimes a rodent will chew the insulation or the wire pinched and the wire gets grounded under the air cowling.
Be careful if you go to unbolt the two 5/16 magneto screws and do not twist them off in the block. Gently peck on their heads first then use a 6 point drive socket to gently break them loose. You will have to re-set the air gap after the mag is loosened/removed. (set at .012) Do not overtighten them when going back but get them good and snug so as the magneto does not come loose and get into the flywheel. They are machine steel screws into aluminum block and the threads sometimes gall.
I use little bit of anti-seize on their threads when going back.
