4hp 'Being a Pig' !!!!

[ninanina]

This used to be dead reliable. Now it won't fire.<br /><br />Got spark, got compression, got new clean fuel, cleaned carb (didn't need it! it was all sparkling!)<br /><br />Even if we spray a bit direct into engine we get absolutely NOTHING...........!!!!! <br /><br />Any ideas most welcome or it's in the dustbin; shame it's in really good nick<br /><br />Thanks anyone

 

[JB]

Re: 4hp 'Being a Pig' !!!!

Ahoy, ninanina.<br /><br />Welcome to iboats. <br /><br />Go to Engine FAQs. There is a troubleshooting guide there.<br /><br />If all of your assumptions are correct it suggests a scavenging or timimg problem, but confirm your assumptions first.<br /><br />Then give us a model number. There have been numerous 4hp engines and the differences may make the differrence.<br /><br />Good luck.

 

[ninanina]

Re: 4hp 'Being a Pig' !!!!

"suggests a scavenging or timimg problem"<br /><br />Hi JB<br />Thanks. I've checked the FAQ's & all checks out OK.. scavenging? is this one of the piston rings? (sorry for ignorance!) & timing?? how on earch do you test / set this on a single cyl 4hp??<br /><br />I'm not sure of model, it's not too old, maybe 1990's..<br /><br />Thanks very much

 

[mikeyzx2]

Re: 4hp 'Being a Pig' !!!!

scavenging is the technical term for how the fuel is drawn into combustion chamber, correct me if I'm wrong since this is what I've gathered from reading. Certain Johnsons/Evinrudes were either "loopers" or loop scavenged, or "crossflows", you'll see those terms thrown around by J/E folks. <br /><br />On the two-stroke , fuel is drawn through manifold and reeds during compression stroke, which creates a vacuum in crankcase. On the downstroke, the piston pressurizes the crankcase and the resulting pressure forces the fuel through ports into combustion chamber. If you've lost compression, have worn crank seals, or bad reeds, it'll inhibit the intake of fuel. Try shooting a dab in through sparkplug holes to see if if fires any. The timing is another issue better left to more knowledgeable folks. <br /><br />If you tried squirting some gas in through the plug holes already then I'm stumped....

 

[ninanina]

Re: 4hp 'Being a Pig' !!!!

Thanks mikey<br /><br />Yeah tried that!!<br /><br />I'm stumped too

 

[mikeyzx2]

Re: 4hp 'Being a Pig' !!!!

hey ninanina, how good a spark are we talking about? I think the spark should jump a 7/16" gap (again correct me if wrong) just grounding the plug to block to see it sparking won't indicate how strong it is. it's fun diagnosing outboards isn't it?

 

[ninanina]

Re: 4hp 'Being a Pig' !!!!

Thanks all<br /><br />A bit of an update:<br /><br />Put a bit of engine oil down the 'plug' hole & after a couple of pulls it fired up; didn't keep it running cos it wasn't in water & it's getting a bit late!<br /><br />What does this suggest? Has the 2 stroke turned into a diesel??? Or does it point to piston rings???<br /><br />Thanks again

 

[Nos4r2]

Re: 4hp 'Being a Pig' !!!!

Now you need a new impeller too...running out of water AT ALL will trash it.<br /><br />Do a compression test on it.