Just stumbled onto this forum. I have a GCV160 engine on my lawn mower, about 5 years old, has had the same problem for 4 years. The engine starts, runs about 3 minutes and then starts stumbling, backfiring, and eventually will stall out. Cutting the throttle to idle will sometimes keep the engine running, wait 15 sec and then take it up to full load, will run 5-10 minutes and then repeats the stumble. Engine stumbled when new once or twice a weekend, but wouldn't die.
If it stalls completely I have to wait 1-2 minutes before I can restart. Last weekend the engine ran perfectly, this weekend cough and sputter. I have tried flushing fuel lines, carburetor flushing/cleaning, new plug, checking keyway, magneto gap. Thought maybe some of you guru's could shed the light. Usually takes 3 or 4 pulls to start, a little smoke at startup. Seemed to stop stumbling when I held the governor open slighty to pick up the RPM for 20-30 seconds, then finished mowing about an hour.

Thanks for any help.

If you have overhead valves, it is possible they are a little out of adjustment,could be an coil breaking up, but usually a coil indication, is it will run till it gets hot, the engine that is and just shut off and when cools will start right back up until it gets hot again.IF it sputtered when brand new, it is in the timing,valves, cam.Sounds like valve adjustment if you have checked everything else.








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It could be valves....... the gcv should be a over head cam though....

For the coil....I've had one make the engine sputter then a few days later it started cutting out. Btw a new, well.... used spare I had fixed the situation...

see if it will run right with the fuel cap loose might not be venting

Tried the loose fuel cap bit to see if that was the problem. I thought maybe water in the fuel but I added a teaspoon of 200 proof to dry out the gas. Drained and cleaned out fuel tank.

It is listed on the Valve cover as OHC so I'm guessing it is not pushrod. Could the cam journals be loose? In listening to the engine when it is misbehaving it sounds like the timing is jumping. I gappend the coil at 0.4mm

The engine sputters etc. the worst in the first 1-5 minutes of operation, air temperature here is a constant 65-70 deg so I can't see the overheating. But a coil breakdown is very plausable. Any way to check it? Would monitoring the spark with a timing light help to see if it was misfiring?

Oil is clean and stays clean after changing.

OhC,PULL THE valve cover off and see if you have pushrods and rocker arms,if you have rocker arms, and pushrods, then the rocker arms should be adjustable,you will have to put piston at top[ dead center, that is the compression stroke before it fires,insert a screw driver into spark plug hole and slowly spin engine until you feel piston come all the way to top,a shade tree trick is to plug hole with your finger until you feel compression escape, this lets you know its the compression stoke coming up before you insert screwdriver, once you find top dead center, insert your feeler guage between valve and rocker arm, see what it reads, find out the valve settings or specs adjust the rocker nuts to tighten or loosen.Honda specs i am not sure of briggs usually set at .003 for intake and .005 for exhaust, if wont run right by specs then its cam lobes.

Just stumbled onto this forum. I have a GCV160 engine on my lawn mower, about 5 years old, has had the same problem for 4 years. The engine starts, runs about 3 minutes and then starts stumbling, backfiring, and eventually will stall out. Cutting the throttle to idle will sometimes keep the engine running, wait 15 sec and then take it up to full load, will run 5-10 minutes and then repeats the stumble. Engine stumbled when new once or twice a weekend, but wouldn't die.
If it stalls completely I have to wait 1-2 minutes before I can restart. Last weekend the engine ran perfectly, this weekend cough and sputter. I have tried flushing fuel lines, carburetor flushing/cleaning, new plug, checking keyway, magneto gap. Thought maybe some of you guru's could shed the light. Usually takes 3 or 4 pulls to start, a little smoke at startup. Seemed to stop stumbling when I held the governor open slighty to pick up the RPM for 20-30 seconds, then finished mowing about an hour.

Thanks for any help. Hi, I'm Herby it is interesting that so many people have the same problem with this engine, I rebuilt two Honda GCV engines one was a GCV 135 but they are basically the same and are prone to the same problem. The 160 had a bent crankshaft so I scavenged one from another engine, the 135 had no compression so I stripped it down and found that water had entered the inlet and the valve had a layer of rust on it so that it wasn't closing properly. To start with I had the same identical problems restarting the GCV160 it started stopped sputtered backfired and so on, I was worried but having read so many threads about it I realised it was probably something simple and not the rebuild, I rechecked the timing and then removed the carb from the engine, looking at the gaskets I decided to replace with new (just in case air was entering) it had a new airfilter so that was fine. I trundled upto the top of the garden to try it out and it would not start but was backfiring and sputtering running then stopping, the only thing I hadn't done was change the spark plug, Hey presto it runs like a new born engine, sweet as a nut. I decided to ad a fuel filter after the petrol tank as I did keep finding bits floating about. In a nutshell I would in future buy a new spark plug before wasting anymore time. I bought the filter from a DIY shop for £3.00.

Thanks Herby - You saved me a swag of time - all I had to do was get the sparkplug as you suggested - Love these easy fixes.

I also have been having troubles with my Honda GCV160 where the engine will stumble and then stop after a few seconds (sometimes longer). I've performed a complete carb cleaning, fuel line check, etc., etc., etc., but until I read this post today nothing helped. Very frustrating.
All I did was run to the store and get a new spark plug and now the engine runs "like a champ". Take if from me, just go get a plug. I even went ahead and registered here just to tell my story due to the lengthy diagnostic period I had with this problem.

Thanks so much "Herby", you ROCK!