1973 18hp - Kohler K482- runs and dies

[1973 18hp 0]

Hi All,

 

Looking for some advice. I got a 73' 18hp that had carb re-done, new intake/exhaust gaskets put on. Fresh fuel. It starts up with help of jumper, runs for 30 seconds and dies out.

 

Sounds like it running fine but noticed when it engaged governor it died out....

 

What is causing this? Newbie here lol. 

 

Attaching video attached.

[ri702bill 10,084]

Welcome!

Is it fuel starvation or the spark goes away?? Are you losing just one cylinder, or both??

Use a xenon bulb inline spark checker, it will flash every time the plug gets voltage from the coil - try it on both cylinders seperately.

[1973 18hp 0]

I checked spark on both cylinders, looks to be working correctly. The ignition was changed from points to electronic ignition. 

 

Note: The engine seems to run a lot longer with the first start-up. Seems like when it gets hotter its run and shuts down faster...

 

Compression 120 psi on both cylinders. Spark plugs super black, put on new spark plugs and just did test "runs" and see them super black already

Edited November 3 by 1973 18hp

[pfrederi 18,979]

When it dies have you tried squirting some gas or carb cleaner in the intake...then will it start??  If it tries to start maybe a fuel supply issue ...vapor lock??? If it doesn't then we  come back to spark..  Coils tend to fail when they get hot.  

[1973 18hp 0]

Its starts each time mostly, but dies shortly after. It runs longest first start after being "cool"

 

I also checked resistance on both coils, seems to check out within spec....

 

Edited November 3 by 1973 18hp

[pfrederi 18,979]

With air cleaner off run her until she starts to die then give a wiff of gas or carb cleaner.  keep it up to see if she continues to run.  

[1973 18hp 0]

okay, she keeps going when I spray in the carb cleaner.. is it fuel pump issue? fuel lines issue? I did a test though and seem to pump fuel through it...or could it be fuel filter? I put a new one on recently. 

 

Edited November 4 by 1973 18hp

[ineedanother 1,729]

That sounds like the fuel tank is not venting. Loosen the cap and see if it keeps running. Could also be a clogged screen on the petcock. 

[1973 18hp 0]

Still an issue, checked the vent on tank/ opened it some. Could it be electrical issue, not charging?

Edited Thursday at 06:25 PM by 1973 18hp

[Gasaholic 334]

Idle circuit problem - Before governor kicks in and closes throttle plate, it is pulling fuel from the main jet venturi, but as the throttle plate closes, it will be pulling fuel (even at "Full throttle no load") from the idle (and transition ports) passages , but if the idle passages and/or ports are clogged, it starves for fuel and dies out (throttle plate opens up again) But it dies before it has time to start pulling fuel charge from main jet - The fact that you can keep it running by adding fuel , its definitely fuel related and usually an idle circuit problem (float level checked? Carb cleaned?) or it is getting unmetered air past the throttle plate (leaking gaskets, manifold leaks?) so either case it is getting more air than fuel for the stoichiometric mix needed (roughly 14.7:1) for proper operation  (Ideal AFR for complete combustion: 14.7 parts air to 1 part fuel by mass)   It's also what we call a "lean surge" when the fuel IS getting there but not quite enough to run smoothly so it "gallops" in RPM's 

[1973 18hp 0]

Thanks! I cleaned carb again, its runs longer now but still dies when it reves up..what is float level check?

[pfrederi 18,979]

[pfrederi 18,979]

Service manual for 482  Click on the fuzy picture