Lawn Mower Fuel Consumption...

[Batpig]

Ladies and Gentlemen,

I've been keeping an eye on the fuel consumption of my new 5hp B&S-powered mower because the exhaust fumes smell a bit rich to me. So far I figure that I've been going through about 0.67L per average sized suburban lawn that I've mowed (the old average that is; say 28p = about 700m2). This compares with what I reckon would have been about 0.45L per lawn with the old Suzy 2-stroke, which by rights should have used more than the new 4-stroke due to the unburnt fuel that chases out the exhaust gases on the ignition/exhaust stroke in a 2-stroke. There's no adjustment screws on the carburettors of these things, so about the only thing I can do is pull out the plug and check the gap...

But I'm wondering nonetheless, do any of you have a handle on how much fuel your 4-stroke is chewing through for your particular size of lawn?

Many Thanks,
Batpig.

[dazzler]

Wouldnt worry till it has about 20 hours or so and then check. My skid steer used heaps as it was being run in but is good now.

unless of course you already have 20 hours in which case

[Batpig]

Thanks Dazzler,

She's done about 11hrs, but no - she's crook mate... Have a look at the photo I took this morning after I pulled out the plug to check the gap. I e-mailed it over to R---r and spoke to the fool who mans the phone. He said "Yeah, I've seen the photo. That's the normal colour" whereupon I replied "Awww Come On! Light tan is normal. That's black! My old Suzy 2-stroke uses not much more than half that much fuel, has no fumes, and the plug is light tan!" to which he said "That's because it's burning oil!" to which I said "Awww Come On! The oil would make it burn darker, not lighter! Normal colour for just about any plug is light tan, like in a car engine! My Briggs is running way too rich!"

Without admitting any problem, he told me to ring Briggs & Stratton, because the motor was "Separately Warrantied..." I rang the dealer, who is a B&S Service Agent, and they didn't buck, so I took it back over to them this afternoon with a letter and the plug sitting in a plastic bag on top of the mower.

Again, the lack of any adjustment screws in the carby has got me worried, because it's hard to see them replacing the whole carb without putting up a fight...

We shall see what comes of it...

Thanks again,
Batpig.

[dazzler]

What a of a business

I think the nails bin hit on the head...very rich...good luck

[peter_sm]

That is running strange for sure. The plug in our Victa Standard 2 stroke was changed after 10 years and still looked fine, with a tan colour.

[Ivan in Oz]

Like one of these?
http://www.verrill.com/moto/sellingg...colorchart.htm

Is your Choke on Just a Little?
That will do it, also. 'Specially the Petrol smell.

[Batpig]

Is your Choke on Just a Little?

No choke on the new ones Ivan - you prime them by pressing a little rubber priming pump bulb sort of button... Wont be "Oil-Fouled" - rings are too new. As they say on that link under the "Carbon-Fouled" example, low compression can do it, as I've seen similar when the plug in the old 2-stroke Suzy wasn't in tight enough. Now although I just wasn't thinking about checking tightness in the "screw-in" direction before I removed it yesterday, I can tell from remembering the reasonable effort required to remove the plug with my 400mm Breaker Bar, that it would have been in sufficiently tight.

That leaves either sticky or bent needle (shouldn't be sticky - she's a 4-stroke and brand new. Could be bent, though...) or non-bouyant float... If the float is made of two thin plastic halves joined at a seam, and there's a little pin hole somewhere along the seam, they can float for a while, and then fill with fuel and sink after ten minutes or so. It's hard to say, but you'd have to figure it's in the carby somewhere. Remember, there's no adjustment screws either - it looks like it's just been cast over where the screws should be. Maybe the castings weren't dressed properly before being joined together back at the factory...

Anyway, the dealer should ring me back sometime today. I'll make a post when I've heard from them. Hopefully they will have pulled the carb off and either replaced it with a "Newie" or gone through it with a reconditioning kit.

Best Wishes,
Batpig.

[Batpig]

Well,

I said I'd post again when I'd heard back from the dealer about the fuel consumption/plug colour problem, and that only happened today - ie. two whole weeks after I gave them the mower, and only then after three separate phone calls...

The verdict (according to the dealer, at any rate...) - blocked Air Filter...

I said, "Aww, C'mon - the thing's brand new. I bought it in February. Everything's been green (we're talking Brisbane remember) since then!"
to which he replied in essence "I've checked the RPM and it's spot on. No adjustments on the Carb, so that can't be out. I've spoken to Briggs, and they agree that it'll be your Air Filter."
"Look," I said, "there may not be any adjustment in the Carb, but that doesn't mean it was put together properly at the factory..."
to which he said "No, it'll be your Air Filter. First thing I checked."
I said "No, can't be. Hasn't been over any dirt. Is the correct heat range Plug in it?"
to which he replied "Yes, the Plug is correct."
The conversation continued in this vein until I could see I was getting nowhere. I'm picking the thing up tomorrow and will obviously start monitoring the fuel consumption all over again...

I am still therefore interested in hearing from anyone who might have a fairly accurate handle on their own 4-stroke mower's fuel consumption.

I am also interested in hearing from anyone on how you go about nailing someone down to do something about a problem that is not entirely obvious and provable - I mean, how can I prove that the motor isn't right; You pull the cord - it starts (probably even easier than a correctly set motor due to the extra richness). You push it over grass - it cuts it. It therefore satisfies the definition of "Fit For Purpose". How can I nail them?..

Any thoughts Folks?

Best Wishes,
Batpig.

[STAR]