Simplicity 7016 - stalls when hot

[burnetma]

I am hoping somebody can point me in the right direction. I have an old 1970 something Simplicity with a 16 HP Briggs engine. After I had the local shop do a carb rebuild and a tune up this spring, it has started to stall after about 1/2 hour of mowing. It will not restart until it cools. I am thinking vapor lock on the carb or condensor. What else could it be? How do I determine the problem? Most importantly, how do I fix it.

Thanks,
Mark

 

[KentT]

I am hoping somebody can point me in the right direction. I have an old 1970 something Simplicity with a 16 HP Briggs engine. After I had the local shop do a carb rebuild and a tune up this spring, it has started to stall after about 1/2 hour of mowing. It will not restart until it cools. I am thinking vapor lock on the carb or condensor. What else could it be? How do I determine the problem? Most importantly, how do I fix it.

Thanks,
Mark

Look for a mouse nest underneath the cooling shroud -- sounds like it is overheating and that's the most common cause.

If that isn't it, check to make sure the carb is adjusted rich enough to not overheat. Pull the spark plug -- if it is brown or white, it's running too lean...

 

[dbdartman]

Another thing to check is the gas cap. If it doesn't vent sufficiently you'll draw a vacuum in the fuel tank which will lean the mixture (creating heat) then stall the engine. After a while sitting the vacuum will dissipate & it'll run normally until it happens all over again. I went through this with my late father's 4HP walk-behind about 10 years ago (it would run normally for 20-30 minutes then start losing power & stall, then wouldn't re-fire for about 20-30 minutes). After I drilled a small hole in the gas cap it ran normally for as long as you wanted it to (& still does today if I choose to use it, which is totally amazing considering how badly I bent the shaft on it 5 years ago then straightened it with a 3lb hammer dial indicator showed it .001" out of round after straightening sometimes it's better to be lucky than good ).

Next time the engine quits open the fuel cap & LISTEN for it sucking air, or FEEL if it's tighter than normal. And of course it's always good to pull the shrouds & make sure it's all clear in there!

 

[simplman]

I spent half of last summer chasing the same problem on my 7016. Did all the same things that have been recommended. Changed fuel filter and all fuel lines with no luck. Finally broke down and changed the coil and never had another problem. Not a small job, but gave me a chance to look at numerous other minor issues. Good Luck

 

[cruzer]

Had the same issue. I found a nest under the cooling shroud...

 

[ChargerAndy]

I have had the same problem with my 1975 for the last 5 years plus. I FINALLY conquered it!!!! I would cut for an hour and the tractor would lose power very quickly and die. If I let it cool, it would run again and quit when hot. I first put in new points and condensor. It didn't help.
The points on this engine are under a little pod cover attached with two screws on the lower left front of the block. I found out that when the tractor quit, the point gap would be 25 thou or so. Spec is 19 I believe. I would reset the gap, and the tractor would fire right up, even if it was hot. But it would quit again in another hour or so. I finally realized that the points cover itself was pushing against the points frame and bending them out of spec as it ran. I know this sounds crazy, but that's what was going on. I carefully creased the cover from the inside with a chisel. I layed it on a block of wood and formed a slight ridge by tapping gently with a hammer. This cover is cast and won't take much. Then I cut two new gaskets to give the points even more room. Since doing this, the tractor has cut for hours without quitting and starts much, much better.

Look into this if your old 16hp Briggs one-lunger is driving you crazy like this!