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Hi all, I posted last year surrounding my Honda GCV160 and am curious to hear your thoughts & experience with different fuel.

Essentially, my GCV160 is still hard to start. It’s nearly a year old and has done barely any hours, the oil is even still clear! I’ve just got in from about 20 pulls of the cord and nothing, nada. Plug is wet through and working, but it’s going nowhere.

I’ve been running it on 99 octane fuel, I’m not sure what this equates to in the US RON system, but it’s the highest we can get in the U.K. reason I’ve been running it on that is due to it having 0% ethanol content, meaning I can store some for a period of time without worrying it’ll go off as quickly.

Now obviously, higher octane fuels resist detonation more than lower octane, is this my issue?!

I would say the octane is not the issue. The wet plug is the issue. Either no spark or none ignitable fuel, ie, bad gas or water

ILENGINE said:

I would say the octane is not the issue. The wet plug is the issue. Either no spark or none ignitable fuel, ie, bad gas or water

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Thanks for the reply, plug is sparking as that was the first thing I checked. The same fuel was fine in the summer, but again just difficult to start from cold. Regardless, I’ve drained the tank and going to try with some different fuel another day

F56JCW said:

Thanks for the reply, plug is sparking as that was the first thing I checked. The same fuel was fine in the summer, but again just difficult to start from cold. Regardless, I’ve drained the tank and going to try with some different fuel another day

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take what fuel you're using now and pour it in a clear glass jar. let it sit for a few minutes, make sure you don't see any phase separation of water on the bottom and fuel on top. even a little bit.

Home made test kit.. Not rocket science.

I ran across one similar to this once - found 2 things going on , one was it was a bit low on oil so the oil level sensor would come into play after it would fire off and shut it down, the other thing was the fuel cap was not vented. Give it a shot of starting fluid and see how it reacts.

Had a similar situation once. A customer reported the same symptoms with his Cub LT1050. It turned out his kids had "topped off" the fuel tank with a garden hose and a bottle of energy drink.

That spark plug was wet too.

Physics 101
ONLY GASSES can BURN
So it is the room temperature volatiles ( often also called aromatics ) that determine if the engine will start or the fuel droplets will deposit on the spark plug.
Nothing to do with Octane ration.
Next problem
Modern fuels ( which are not petrol ) conduct electricity at combustion pressures
So if the plug is damp then the spark will run to ground down the side of the plug when you try to start it so no spark = no bang.
On top of that
Modern plugs do not have glaze on the insulator so once wet they stay wet till BURNED OFF and even worse, attempts to clean with a wire brush will leave metal traces on the insulator for the spark to travel down .

bertsmobile1 said:

Modern plugs do not have glaze on the insulator so once wet they stay wet till BURNED OFF and even worse, attempts to clean with a wire brush will leave metal traces on the insulator for the spark to travel down .

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Yeah the wire brush thing is bad. Have had cust equip come in where they did a tune up and wire brushed the plug and now it doesn't work. A sand blast cleaner is better and i use one to clean the plugs on my IH184 tractor that is a bit if an oil burner and i don't run it hard enough to keep the plugs clean even using D21 (hot) plugs. On most OPE not worth trying to clean a plug when they cost so little.

Here are two thoughts from an amateur. First:Have you run over something, like a stump? If so, you may have a timing issue. I have seen motors where the flywheel has moved but not completely sheared the woodruff key. Second thought: I had that same engine and the plug was sparking, so explored all other possibilities including rebuilding the carb. A good friend, who was as far from mechanically inclined as they come, kept telling me to replace the plug. Eventually I did. And that is how I discovered that a plug can spark but not good enough.

Update for all who are interested, firstly thank you for all your responses, I appreciate your time.

I drained the tank and float bowl and went out to get some standard E10, 95 octane fuel. Filled the tank and it fired 4th pull.

I haven’t had the chance to check the previous fuel for any water content, but with it being 0% ethanol and in a dry atmosphere I’d be sceptical, my 2 stroke equipment also still runs fine on it which is a surprise! The mystery I’d say, remains mostly unsolved

Two additional thoughts from someone who aspires to be considered an amateur: 1) gotta agree with @Oddjob - we run four jet skis and it took some racers to open my eyes to how, “spark plugs are cheap” and how a new plug can make a world of difference in less than ideal (I.e., marine, wet, cold, damp) conditions after as few as 30 hours in wet environs (I.e., IN the water); and, 2) even non ethanol goes “stale” but, we’ve had Absotively ZERO a fuel issues since a neighbor who works in the international petroleum industry turned us onto PRI-G: https://www.amazon.com/PRI-PRI-16-G...hvlocphy=&hvtargid=pla-4583589115258382&psc=1

PRI-G is NOT a fuel “stabilizer” (Sta-bil is a rudimentary stabilizer) - I am not a chemist but I have had a petrol chemist explain to me how, molecularly, PRI-G is a fuel RESTORER and in a decade I have racked up a half dozen experiences that approach defying logic in getting friends abandoned and neglected car, small engine and boat engines running when nothing else worked!

PRI-D is for diesel.

I don’t even debate the unmatched efficacy of PRI-G any longer but, here are some additional independent sources of info:

F56JCW said:

Update for all who are interested, firstly thank you for all your responses, I appreciate your time.

I drained the tank and float bowl and went out to get some standard E10, 95 octane fuel. Filled the tank and it fired 4th pull.

I haven’t had the chance to check the previous fuel for any water content, but with it being 0% ethanol and in a dry atmosphere I’d be sceptical, my 2 stroke equipment also still runs fine on it which is a surprise! The mystery I’d say, remains mostly unsolved

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Once again read my previous post.
If there are no volatiles left in the fuel then it will not start because there is no GAS in the cylinder, just drops of fuel.
This applies to e0 e10 e15 e 85, 91 octane, 95 octane ,98 octane or even 100+ octane avgas
In summer the volatiles evaporate readily but in winter they don't because they are too cold.
Just like trying to get a kerro lamp to burn, you have to heat the burner first with metho to get it hot enough to vapourise the liquid kerro.
This is one reason why summer & winter fuels are different.

F56JCW said:

Thanks for the reply, plug is sparking as that was the first thing I checked. The same fuel was fine in the summer, but again just difficult to start from cold. Regardless, I’ve drained the tank and going to try with some different fuel another day

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F56JCW If you are using an gas containing ethanol it will basically be of no use in small engines after a couple of months and in a vented fuel system will absorb a lot of moisture( water), use non-ethanol gas if available.