How-To: Install Fuel Filters On 4-Cycle Engines
By Kevin Pace
In the never-ending fight for truth, justice, and efficiently running 4-cycle engines, the newest arch nemesis of mowers and small lawn equipment everywhere has reared its ugly head: ethanol! As crude oil prices rise, gas companies are trying to cut costs and encourage renewable energy sources by adding ethanol to their gasoline mixture — up to 30% by volume in some parts of the U.S. For an easy way to combat the negative effects of ethanol in your small engine, you can install an inline fuel filter. Follow the jump to learn how.
First, I’m sure many of you are wondering why ethanol is so bad for engines in the first place. Well, it’s actually not the ethanol itself that’s the problem, it’s what the ethanol has a tendency to attract — water — which is a big no-no when it comes to small engines. On a molecular level, ethanol and water attract each other like magnets, causing the ethanol to suck water into the fuel lines of 4-cycle engines when there’s even the slightest humidity in the air.
You can easily remedy this by adding an inline fuel filter to your 4-cycle engines. Most lawn equipment uses a 1/4″ fuel line, and the standard size fuel filter from Briggs & Stratton will fit the majority of the models on the market. The fuel filter blocks all water as well as any impurities in the gas before it gets into the engine.
Installation is easy: Simply find the fuel line running from your gas tank into your engine intake port, and cut it cleanly with a sharp utility cutter. Install the fuel filter between the cut, with the smaller-diameter side facing the gas tank and the larger-diameter side facing the intake port. Secure it in place with small spring clamps on each side, and you’re done. Of course, you want to empty all the gas out of the gas tank and fuel lines beforehand.
This $5 worth of parts and five minutes of your time can greatly increase the lifespan and efficiency of your 4-cycle engines. You can find all the parts at home improvement stores or online.
Inline Fuel Filter [Briggs & Stratton]
May 26th, 2009 at 11:41 am
There is no way that filter is going to be filtering out any water. Its a 150 micron filter, which will do a great job filtering out dirt and twigs that might get in when you’re filling the tank, but its not going to do anything about water.
And really I find it incredibly hard to believe that ethanol is going to have any negative effects on a small displacement, properly maintained engine.
May 26th, 2009 at 12:15 pm
I thought it was just me. The link between this filter and water escapes me.
If the filter did trap water, eventually it would reach a saturation point and either begin to pass water or block any liquid flow.
If water contamination is an issue–and I am not saying it isn’t–I’d think it was a better idea to add a dose of fuel drier (isopropyl alcohol, mostly) to the tank on fill-up.
If the problem is debris in the fuel, a filter funnel and this sort of filter on the engine may be a good solution.
May 26th, 2009 at 12:19 pm
I have to agree with Jim. I’m pretty sure you have to get down to the 10 or 20 micron range before you start filtering water, and that’s ony when it has separated from straight gasoline. Add more ethanol (an alchohol, keeps water in suspension) and even the water can pass through a very fine filter.
I don’t see ethanol, or even small amounts of water, as being a problem for most small engines. A fuel filter can’t hurt, but this one won’t work for the intended purposes.
May 26th, 2009 at 12:24 pm
Scott: I’m pretty sure adding fuel drier (another alchohol) is the same as adding more ethanol. You’re not getting rid of the water, just keeping it in suspension (preventing it from separating out). It’s when it is separated that it freezes, which is why most people use fuel drier (for winter).
May 26th, 2009 at 12:40 pm
bah, its not pulling water out. My diesel car has a water seperator built into the filter, but thats a seperate issue (and i have never emptied it after 250k miles on two different diesels cars.
but this would be great for dirt dust and other junk that easily gets into the tank.
How many people have had problems with debris in engines. I am sure a lot, i am not one of them though. (yet)
good idea, wrong explnation.
May 26th, 2009 at 12:41 pm
On another note, other than the water/ethanol/filter issues being correct/incorrect in this article, notice that the power washer pictured above this article about gas engine maintenance, is electric… kinda funny…
May 26th, 2009 at 12:48 pm
I am fortunate that I can still get premium gas without ethanol. That works like the gas that was good enough for your father. I have been running all my yard equipment on that premium gas.
Premium ran better in my Pathfinder, too. I’ve sidestepped the ethanol gas problem there by getting a Diesel Jeep Liberty. That has its own problems but, we will learn to cope.
I don’t think I want to try a Diesel lawn mower.
May 26th, 2009 at 12:55 pm
Fred Boness Says:
…Premium ran better in my Pathfinder, too.
…and my Ranger runs better after I wash it.
May 26th, 2009 at 1:16 pm
Kevin,
You really need to update this post. As others have pointed out, an inline fuel filter will only remove particulate matter. Fuel-water separators will do the trick, but you aren’t likely to want to put one on a small motor.
Many older lawn mowers and tractors had a small glass bowl with a screen on top. Although not recommended anymore for safety reasons, they do work fine and do the job well. However, they don’t function unless upright, and hence aren’t a good idea for most small gas motors.
Please update your post to reflect this information. You’ve given a good tip (fuel filters are rarely a bad idea), but this is misinformation.
Thanks,
P.
May 26th, 2009 at 6:26 pm
I’m not so sure it is misinformation. I’ve got a Coleman filter funnel for camp stove fuel, and it claims to remove water. I tried it, and sure enough the white gas goes through just fine but water will bead up on the top of the filter. I think it has something to do with not being able to wet the material.
I sure wouldn’t bet against it working.
May 26th, 2009 at 6:57 pm
MeasureOnceCutTwice why do you think the two filters are comparable? Fuel/Water separating filters for aircraft and boat use are typically about 100 microns. The specs on this cheap B&S filter says it filters to 150 microns.
I agree with everyone else here that says the author shouldn’t be making claims he can’t back up. Isn’t that the essence of good journalism?
May 26th, 2009 at 8:00 pm
Doesn’t STABIL fuel additive keep water from coming out of solution in your gas? I add it to all my gas.
May 26th, 2009 at 8:42 pm
Well, it’s very nice to see such an in depth conversation about my article. Makes me happy knowing my stuff is being read. I would like to address a few points.
After the first few posts earlier today, I decided to call my contact at Briggs & Stratton to see if he could answer a few questions for me. The bulk of the information used in this article was pulled from a engine docket I received at work that was assembled by Briggs for us. My contact did confirm for me that all the information contained in the docket was factual. According to Briggs & Stratton, this 150 micron filter will indeed filter the water trapped in your gas tank before it hits the carburetor. While the technical aspects of it escape me, his explanation revolved around the joint workings of both the filter and the shape of the device. Either component alone would not be able to filter water, but the combined aspects of it will. Should you wish to further dispute this, I would recommend contacting Briggs.
Secondly, thanks for pointing out my mistake on the picture Sean. I Googled pressure washer and saw a gas one but wouldn’t you know it, clicked on the wrong picture and ended up with an electric. I would change it but this brings me to the third point.
Once an article is posted, the authors can’t edit it. Only the Toolmonger editorial staff can so if you’d like to see something changed they would be the ones to contact.
Thank you all very much for the comments. I learned a few interesting things today I did not expect to find out when I woke up and I look forward to learning many more as I continue submitting articles for this wonderful resource.
May 26th, 2009 at 9:07 pm
I won’t point out that the pressure washer shown in the lead-in photo would not benefit from this modification due to it’s being powered by an electric motor.
May 27th, 2009 at 5:42 am
Sorry Kevin, the Briggs guy is feeding you a load of crap, or is talking about a different filter. Ignoring the fact that the filter has no “special shape”, and that I find it extremely hard to believe that a 150micron filter would pull water out of gas, whats going to happen too all this water? There is no way for it to drain off, or evaporate.
May 27th, 2009 at 6:10 am
@Fred Boness:
Putting premium gas in your 2 or 4 cycle small home engines is a bad idea. They simply don’t have the combustion ratios needed to fully burn the fuel, which leads to numerous problems.
As for your Pathfinder — unless the engine was designed to use premium fuel, it didn’t run any better either. You just convinced yourself that paying more was worth it.
My Maxima recommends premium fuel, but it runs just fine on 87 octane regular. No difference in mileage either. Sure, I sacrificed some power, but since I’m not running it at 110+ mph anyway, or flooring it off the line, I really don’t care.
May 27th, 2009 at 11:30 am
Higher octanes allow an engine to run higher compression ratios without knocking occurring. Period. That’s it. Nothing else. The only way you can get more power out of higher octane gas is if you run your engine at at a higher compression ratio, and that’s not the way 99.999% of the cars made today run their engines.
With the exception of truly high performance (Lamborghini, Maserati , etc) cars, you won’t see any change at all in the performance of your vehicle with higher octane gas. The Pathfinder didn’t get any stronger on high octane and the Maxima didn’t sacrifice any power on lower octane.
Only a sucker or the ignorant purchase high octane gas for normal vehicles.
Here’s some light reading for those seeking to educate themselves. In particular, note the government website at the bottom. It’s the Federal Trade Commission, and among other things they say, “Unless your engine is knocking, buying higher octane gasoline is a waste of money, too.”:
http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question90.htm
http://en.wikipedia.org/wiki/Octane_rating
http://www.ftc.gov/bcp/edu/pubs/consumer/autos/aut12.shtm