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I was recently given a non-running Huskee 42" mower with a Briggs knock-off MTD engine called Powermore 420CC.

The owner said it ran about 6 months (he bought it in the summer of 2015 but it didn't last the summer).

I hooked up a battery and the engine cranked normally but no start - not even a cough.

My first diagnostic step was to remove the valve cover since a "repair man" told the prior owner it wasn't worth repairing. Lo and behold, I found that the intake rocker arm was missing. Ordered the part - set the valves and the engine would not turn over even though it had without the rocker arm. I noticed when I rotated the engine by hand that it would turn but not make a full revolution.

My next inspection step was to remove the head. Everything looked good except there was an excess of carbon on the piston and inside the head. Ok, I'll clean that later. However, that wouldn't stop an engine from rotating so I was now thinking something really bad was wrong in the engine.

I took the bottom cover off and was pleased to see it actually has an oil pump versus a slinger. Everything looked perfect in there - no metal shavings, no sludge, no dirt, it was spotless and all parts looked excellent. Since there must be a problem with the valve train, I pulled the cam. Like everything else, it was in perfect condition, at least to my naked eyes. No flat spots or signs of wear.

So it freely cranked without an intake rocker arm but would not crank with the rocker arm. The cam was good, I better look more closely at that intake valve. So I removed the keeper but the valve didn't budge. The excess carbon had actually caused the valve to freeze closed in the guide. After a few taps on the inside end of the valve and its out for a closer inspection. Surprisingly, the valve looks to be in excellent condition once all the carbon is removed.

Reassemble the engine, install it on the mower, drain the gas and replace with fresh and crank and crank and crank. Nothing and I mean it didn't hit a stroke a single time. It had air (no air filter), gas (unburned gas was coming out of the exhaust port - muffler not installed) and spark. I had put one of those inline spark testers and it sparked just fine. Thinking maybe the spark was weak, I reset the gap to .0010". That didn't change the spark as I had used the old business card trick earlier.

Ok, so the spark is not sparking at the correct moment so I pulled the flywheel to make sure the key was installed and not sheered. It also was in perfect condition.

Getting desperate (even though it was sparking) I pulled the kill wire off of the coil. On the next start attempt the engine fired 2-3 times but did not actually start. Scratching my bald head - how could disconnecting the kill wire impact the engine as it was sparking before. I came to the conclusion it was just a fluke because after many attempts to start it only coughed twice, both times firing 2 or 3 times. I am convinced it was a bad coincidence that it fired the first time after I disconnected the kill wire.

So here I am - cranking with a properly timed spark, gas in the cylinder and free air but no start.

Diagnostic ideas are welcome. I think my next step is to clean/service the carb. Maybe I have gas but not being properly delivered.

The details on the machine are in the attachments. The engine model is 4P90HUB. Single cylinder B&S clone.

Could it be possible that the valve while being stuck open made light contact with the piston, which bent the valve head slightly and now isn't setting flat on the seat preventing it from properly sealing.

Remove the carb and muffler. Install a NEW spark plug. Spray about 1 second worth of starting fluid, not carb cleaner ir the like, In the intake port. Try to start engine. Should fire up for a few seconds and die. If it doesn't start diagnostics. Did it spit back out of the carb? Did it spit fire out of the exhaust? Did it run but pooly? Did it not run at all? When You had the head off did you check for valves sealing properly? Did you check the rings?
I am not a big fan of the Powerless engines. Or Huskee for that matter but if it was free what tbe heck.

ILENGINE said:

Could it be possible that the valve while being stuck open made light contact with the piston, which bent the valve head slightly and now isn't setting flat on the seat preventing it from properly sealing.

Click to expand...

The valve appears to be seating properly. While I have not tested the compression, I know by turning the flywheel by hand that it has good compression.

Hammermechanicman said:

Remove the carb and muffler. Install a NEW spark plug. Spray about 1 second worth of starting fluid, not carb cleaner ir the like, In the intake port. Try to start engine. Should fire up for a few seconds and die. If it doesn't start diagnostics. Did it spit back out of the carb? Did it spit fire out of the exhaust? Did it run but pooly? Did it not run at all? When You had the head off did you check for valves sealing properly? Did you check the rings?
I am not a big fan of the Powerless engines. Or Huskee for that matter but if it was free what tbe heck.

Click to expand...

The valve appears to be seating properly. While I have not tested the compression, I know by turning the flywheel by hand that it has good compression. I will need to buy starting fluid to test further test the engine.

The spark plug was new - I think that was part of the prior owners diagnostic. However, I also installed a new plug, but it made no difference.

The piston top and cylinder were without damage. Thinking more on this after my initial post - why did the combustion chamber have so much carbon build-up to begin with. This again points me to the carb as the source of the original cause of the saga.

Next test - starter fluid.

I have noticed the valve guides working there way out of the overhead valve briggs heads, When they come out far enough the rocker arm hits it and bends the push rod and changes the valve gap setting. If the intake valve does not open then there will be no fuel air mixture enter the cylinder and explain why it does not fire. I remove the valve keeper and valve spring and put a deep well socket over the valve and drive the valve guide back down, Take a sharp punch and drive little dents all around the valve guide to keep it from coming back out. I do not remove the head I remove the spark plug and fill the cylinder with small rope to hold the valve up will doing the repair

Rocky, I have seen Taryl of Taryl Fixes All do that.

Hammermechanicman said:

Remove the carb and muffler. Install a NEW spark plug. Spray about 1 second worth of starting fluid, not carb cleaner ir the like, In the intake port. Try to start engine. Should fire up for a few seconds and die. If it doesn't start diagnostics. Did it spit back out of the carb? Did it spit fire out of the exhaust? Did it run but pooly? Did it not run at all? When You had the head off did you check for valves sealing properly? Did you check the rings?
I am not a big fan of the Powerless engines. Or Huskee for that matter but if it was free what tbe heck.

Click to expand...

Hammermechanicman, I started the engine with starter fluid. It ran as long as I provided starting fluid. So I think this proves that my problem is in the carb. I also noticed that it would not start when the kill wire was connected. I spent a while checking the safety switches and couldn't find any problems with them. For now I will focus on the carb, but that has to wait a week or two as other responsibilities have risen to the top of the priority list.

Thanks for the help.

You are right, Taryl of Taryl Fixes All lives a hour north of me , up by the two Nudist Colonies in Roselawn In. Taryl said everything those two places bring in have bent cranks and Uncle Andy said it was true .I like all of his videos.

for the kill wire.
Stick your multimeter on it
If it shows continuity to ground then you have wiring problem.
One at a time disconnect each of the safety switches till the wire goes open circuit and "there's yer dinner " to use a familiar quote.
If you have the small 4 pin flat plug on the seat switch look deep into the bottom of the plug because a lot of them have a bridge contact at the bottom to prevent people from disconnecting the seat switch .
And remember that the switches are connected by wires and the safety circuit is a GROUNDING circuit so any wire shorting to ground will kill the engine .

as for the engine proper, do a leak down test chances are one valve is hangine open, or the valve seat has shifted or the valve guide is loose.

Easiest way to "test" the carb is remove it, leave the fuel line attached, turn it sideways and blow high volume low pressure air through it
You should be able to see the fuel air mist coming out of the carb.

I just realized I didn't close the loop on this thread. I cleaned the carb and install a carb kit and it resolved my starting issue. So the order of failure was bad carburation which lead to extremely rich fuel/air mixture which lead to carbon build up on valve causing valve to stick.