Tecumseh H35-45572P Idle Problem

[KE4AVB]

I have above in the shop that giving problems. I Have both cleaned and replaced t he carburetor. The engine run strong from mid to full throttle. Then when it is returned to idle as it settle in to idle mode it just dies as if the kill switch is activated.

Any Ideas?

Would excessive intake clearance cause this?

[bgsengine]

Try boosting up the idle stop? Ive had them do that just when they were getting "tired" (tolerance stacking) , boosting up the idle stop screw a bit where it was smooth while holding throttle plate to dead idle often did the trick, they idled a bit faster than they should but unless it is a clutch engagement issue, etc, I probably wouldnt be an issue..

[KE4AVB]

Tried that trick engine way too fast. The min place I found was half throttle (2500 rpm (Idle crack screw nearly all the way in)) which way too faster for slow walking the tiller. It should be able to run under 2000 rpms

[aj-allen]

I'm sure that you are aware but the idle mixture screw on this carb meters air not fuel so turning it in enriches the mixture turning it out leans it.

[bgsengine]

Yeah I'm sure KE4 is well aware of the differences.. Other thing that comes to mind might be a check of the throttle plate positioning on the throttle shaft (sometimes just cracking throttle plate screws loose a bit and re-position plate slightly can do the trick) Possible the plate likes to "stick" when it snaps back to idle, and slow to re-open by which time engine's already stalling out .. gotta try and think through how air flow may be working as it idles back down - I suppose too small of valve clearance might let intake valve hang a bit.. maybe exhaust back-pressure a possibility..? I Have had a couple engines that wanted to do that (and seem to recall they might both have been Tecumseh) but other than as I mentioned I don't clearly recall any specific fixe4s to the issue.. reminds me of some 2-cycle engines that liked to do the same thing (chainsaws, trimmers) I'd also wonder if it could be an intermittent ignition mis-fire.. under load or at steady throttle speeds, momentum might be enough to keep 'em going through a couple misfires, but going lean (as throttle snaps back closed to idle down) might be enough to kill the ignition long enough that it can't recover once it settles into idle? could be a combination of several things that by themselves would not cause any problems (low compression, valve wear, sloppy tolerances, etc?) Just tossing some other ideas out there..

[KE4AVB]

Killed project...

When I removed the head I found the valve guides worn out and replacement OS valves not available at my distributors though I find a few NOS ones available. This plus cylinder wear makes it not economical to repair. Already installed a $40 NOS fan and the customer is looking for it to be fixed cheaply. And I am not going to spend $35 for reamer that will be used on an one time project; unless, it was my own equipment.

The worn valve guides appears to be the root of the not idling problem as I am now getting spit back though the carburetor when the temp was down to 70F yesterday morning.

As for the carburetor I had to transfer the old throttle shaft to the new carburetor due how the linkage connected was backwards on the new carburetor and I did make sure there was no binding. No amount of air bleed worked.