Hello! First time poster here. I’m seeking some help from anyone with knowledge of the predator 670 engines. I repowered my tractor two years ago and it has worked flawlessly, until today. It’s starts and runs perfectly, blowing snow for about 30 minutes and then it acts like it’s starving for fuel. When it does this I have to run it on full choke to limp it home. I let it sit and cool off for a bit and it starts and runs fine for another 30 minutes then same thing. Things I’ve already checked. Fuel tank is venting properly, drained fuel tank and filled with fresh fuel, replaced fuel filter, replaced spark plugs (original ones were VERY black). It’s about 4 degrees here today in iowa, but I have used this machine in -10 weather before without issue. Any help is greatly appreciated!
Predator 670 issues.
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The carb may be icing up in the venturi. As air passes thru the venturi in the carb it increases in velocity which has a cooling effect causing the moisture in the air to freeze and block the fuel nozzle. This is why many snow blower engines have some heat directed to the carb or the incoming air to prevent icing. Dry Gas used to be sold for years before fuel injection to prevent carb icing. Dry Gas which is isopropyl alcohol and when added to the fuel tank would reduce or prevent carb icing. I don't know if it is sold at auto parts stores any more, I spotted some at a surplus store years back and bought a 6 pack of it and had to use it in both of my Onan powered Ingersoll tractors that I used for snow removal back when. Sea Foam fuel additive may work, but not sure. Years back Evinrude and Johnson outboards used to sell OMC Fuel Conditioner to prevent carb icing, I don't know if it is available any more. 
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Both Onan and Briggs & Stratton horizontal shaft engines have a hose or a molded piece that allows air direct from the flywheel fan to blow into the air filter housing. Briggs makes a blocking plug to put in the blower housing to block the air from entering the air filter housing. When I get Briggs Vanguard powered tractors in for service or re power, I remove the molded piece and install the blocking plug in the blower housing. Check your Predator engine to see if it has this type of air flow into the air filter housing and if it does, consider removing it and blocking the hole in the blower housing.
@Bob MacGregor
Would HEET be essentially the same product as Dry gas?
Would HEET be essentially the same product as Dry gas?
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Yes, I just went out in my garage and found the package!
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When I was using an SB48 on my 4018 I reversed the shoes so they were under the blower, just a thought.
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I agree with the carb icing . If you can direct some warm air from the exhaust it might help. Had a crew boat that would ice up bad in the winter many years ago. We would have to close up the air intake on the hull in an attempt to keep the engine room warm. Never really helped.
Well, I know others might differ here but my two cents and experience! Never, I repeat never use ethanol gas in a corroborated engine, period! I have nopt only been through exactly your issues with an Onan and ALSO a B&S 18HP. Ethanol gas absorbs WATER!!! known fact. Anyone that lives in an area that freezes regularly needs to find a source of NON Ethanol gas and yes I know its more expensive too. If you do you will probably NEVER have gas freezing problems again. Tried all the fixes with ethanol additives and they don't WORK and frankly a wast of money too. In all my corroborated engines I NEVER, EVER use anything else summer or winter. Never had an issue since. There are many, many instances on the internet for this..
Just so every knows - ethanol gas is MADE in the tanker! yes as I said TANKER. Ethanol gas can not and is not stored in the refinery storage tanks as it cause corrosion and produces water! Ethanol is added as the tanker is being filled for delivery. Don't believe me just check it yourself.
There were many law suites files and won when ethanol was added to gas as a supposed improvement to emissions. The fact is that that was used as an excuse to add it but the real reason was an underhanded way to pacify farmers that had a grain storage/sell problem. Instead of sending/selling grain to third world countries to eleviate food hunger (probably at lower prices) they wanted a constant money supply. Persuaded the government, through lobbying, and created this fiascoe of adding it to fuel for "emmisions improvement". guess what it actually reduces the MPG of most engines that actually INCREASE emissions as you burn more gas too. Sorry for the vent.. Just so you know when I run my Subaru of Non Ethanol I get over 43 MPG during the summer and Ethanol gas 34 MPG you work it out...+
BTW, the government knew the damage will cause to "small engines" mainly used for garden care and just did not care (all to do with lobbying). Supplements used to counteract the ethanol do not help at all! as they don't remove the ethanol. Luckily for me I live in a State (NY) that allows non-ethanol gas to be sold at gas stations (but at a high premium) whereas states like Mass have made that illegal and only allow sale through place like Lowe's, etc and a very high premium. It took many years, and is still a problem, to make carbonated engines even run and most ONLY during the summer months when temperatures are higher. Just know that once blended with gas, ethanol absorbs water, at the moment of blend! by the time you can purchase that gas its at least a few hours or often days later and you are buying a gas/water mix. Places that go south of 32 degrees can expect the water to freeze in the carb! Add to that the corrosive effects on ALL, not even some, carbs produced before 2000 then that's your issue EVERY time. For me a purchased a B&S 18HP engine in 2010 and it did not last the winter 2010/2011 without freezing and needing a carb strip and repair (I found a carb bowl coroded and the shut off solenoid at the bottom of the bowl stuck after less than 15 hours of use.
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If I lived in an area with no non ethanol gas I would remove the ethanol myself. There are youtube videos on how to do it. As you mentioned ethanol is attracted to water. It is as simple as adding water to the gas then stir it vigorously and let it sit for a day or two then siphon off the gas. Using a clear bottle from a water cooler makes it easy to see when the little water droplets have all settled (stratified) out of the gas.
Cheers,
Gordy
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No disrespect but you guys have some weird problems. I run regular grade pump gasoline (15% ethanol blend) in everything I own with an engine without the problems you are describing. My 1957 Mercury outboard has ran on it and been stored over the winter with it in the bowl, with the original cork float, since they started cutting gas with ethanol and it's surgically clean inside.
Per the original issue at hand, I've heard of predator carbs icing up before when temps are in the teens on both ethanol blended and non ethanol gas. The latent heat of vaporization of any fuel pulls heat out of the carburetor and intake manifold.
Hi FastEddie, all I can say my friend is that your specific engine has an aluminum carb material that is not effected by ethanol and that might be because it was designed as an outboard motor to function in a salt based environment too ?! almost every carb based small engine used on land before 2005-6 has the problem with ethanol gas. It is well known and documented that ethanol gas absorbs water! water freezes below 32 F/0 C and no matter what physics you use that does not change. Ethanol is chemically not compatible with Gas either. From the moment they are mixed together they are trying to separate which is why they only mix during transport and Ethanol absorbs water and freezes. Why do you think that the advise given is NEVER EVER let you gas tank go below 1/4 full during the winter!!!
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