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Hi.

Baffled by why my YT3000 21hp ohv(model 331977) won't start without a squirt of starting fluid. Over winter I replaced the head gasket as it was blowing smoke. I reset the valves clearances according to specifications and buttoned it up.

Went to start it this past week and it slowly cranks but will not start. (Battery fully charged). I eventually ended up spraying a bit of starting fluid into the carb and it fired right up. Stays running and runs smooth as silk. Shut it off and come back...same issue...will not start without a hit of spray.

No idea what it could be....It always started fine last year, just smoked like crazy.

Thanks for any guidance!

Mike

Make sure the choke is fully closed when in the choke position.

did it start after you worked on it, or is this the first try?

sgkent said:

did it start after you worked on it, or is this the first try?

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Thanks for the reply. This was the first attempt since I worked on it. I thought it maybe that I did not adjust the valve clearances correctly...went back and checked/re-did them....still same issue.

StarTech said:

Make sure the choke is fully closed when in the choke position.

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Thanks for replying. I will check that....

One other observation....when starting with no fluid the motor will turn slowly, stopping sometimes before resuming. When spray is applied, the motor turns very quickly and starts...

Thanks in advance for any help here.

While adjusting the valves did you check for the ACR bump of the intake valve rocker? If not present then the camshaft's ACR has failed. Quite common for the 793880 camshaft ARC to fail in the 31, 330000 series

I bet a wooden nickel it's a fuel delivery issue. This time of year people are dragging out mowers with stale E-10 fuel from LAST YEAR.

Clean the cooling fins while you are at it.

StarTech said:

While adjusting the valves did you check for the ACR bump of the intake valve rocker? If not present then the camshaft's ACR has failed. Quite common for the 793880 camshaft ARC to fail in the 31, 330000 series

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Thanks, that does make sense. I did not notice that. I set TDC and then backed off 1/4" before setting clearances. The ACR bump you mention is when the valve opens a bit to relieve compression...at what point in my example here would I start to see that open.. thanks for your help!

omerta14 said:

Thanks, that does make sense. I did not notice that. I set TDC and then backed off 1/4" before setting clearances. The ACR bump you mention is when the valve opens a bit to relieve compression...at what point in my example here would I start to see that open.. thanks for your help!

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With a maybe 0.002" feeler gauge between the rocker lever and valve stem and on compression stroke you can tell if there is an ACR bump and at what time in the stroke .

SeniorCitizen said:

With a maybe 0.002" feeler gauge between the rocker lever and valve stem and on compression stroke you can tell if there is an ACR bump and at what time in the stroke .

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Just before the engine fully at TDC while turning in normal rotation direction. Also valve are set with piston down 1/4" pass TDC. I usually adjust the opposite valve when one valve is fully open.

sounds like a fuel, fuel mixture, or vacuum leak issue. The starting fluid is ether and it is a substitute for gasoline vapor. It is very explosive so it doesn't take much. Since it starts with the ether, it would appear everything is there except gasoline fumes. If it is old gas, that can make it impossible to start too.

Set the valves @ TDC, ignoring the ACR. Set them cold. 0.004-6" . It does sound like a fuel problem. Check needle and seat for operation and flow. Check (remove and clean) ALL Battery cable/solenoid/starter connections. File Battery posts 'bright'.

slomo said:

I bet a wooden nickel it's a fuel delivery issue. This time of year people are dragging out mowers with stale E-10 fuel from LAST YEAR.

Clean the cooling fins while you are at it.

Click to expand...

I also think it could be fuel. The after fire solenoid on the bottom of the carb when dirty or weak may pull away from its spring loaded fuel shut off valve at 12 volts, but at cranking speed, you only have 9 volts and it may not allow fuel to main jet. once it fires and the starter current is reduced, the solenoid clicks. Test it with a 9 volt battery. Otherwise, it may be not getting that compression relief.