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Anyone else having small engine problems?

About a month ago my twin cylinder Briggs lawn mower started stumbling pretty bad. I had a carb kit on hand so put in the fuel pump diaphram portion of it and filter. Was fine for a month, then today it did the same thing-starved for fuel. So I got another fuel pump kit and used the rest of the carb kit to replace the jets etc. The guy at NAPA where I got another fuel pump seemed to think the gas was causing the carbs to clog up. Seems to run fine again but I’m wondering if I should add something to the gas. The gas is always pretty fresh in the summer and use Mobil non-oxygenated.

I’ve haven’t had any problems with my small engines. I use Marathon non-oxy gas.

You still north of the Twin Cities, Bing?


Naw, I’m south in Faribault but work in St. Paul so I’m all over. Maybe it was workmanship or maybe it was the carb after all. I usually take pretty good car of the carbs though with preventative overhauls.

Just try harder. Use Sta-Bil in your gasoline during the Winter months. Then do better by using it in the Summer too. It prevents gum and varnish from forming and clogging the carb.

this could be a reason…

Were there any signs of gumming or varnish in the bowl or on the jets of your carb? If there were, I’ve had one or two small engine carbs where the only option (after replacing the jets) was to soak the carb overnight in a bucket of real carburetor cleaner solution. (The spray can stuff doesn’t work.)

The bottom of the fuel tank often has a small screen in it to filter debris. Is that screen clean?

I’m assuming you have a strong spark and that your plugs and wires are good.

That’s an interesting article. After reading it, one thing the OP could try (if he can’t get non-ethanol fuel) is to try running the mower on a gallon of Coleman Fuel. If the engine runs smoothly again, he knows where the problem is (and he’s not alone).

Thanks for sharing that link.

Don’t forget to check the vent hole in your gas tank cap. If air can’t get in, fuel can’t get out.

No issues with my power equipment however I only buy Honda engines. Not for reliability (if better?) but the fact they seem to only make about 1/2 the noise and vibration of a domestic brand.

I’ve actually just possibly started having this issue with my briggs. I hadn’t actually thought of the ethanol problem so I’m glad you posted this.

Everything was clean as a whistle inside. I pulled the cap off so wasn’t venting but definately fuel starvation. Would only stay running on full choke. I might have just had a bad fuel pump diaphram or something from last month. I guess I’ll start using Stabil in the summer too.

A friend of mine had exactly the same problem with his twin cylinder Briggs & Stratton engine on a riding lawn mower. He had the carburetor rebuilt twice by one shop and the problem kept reoccuring. A second shop told him that these carbuetors are really hard to rebuild and replaced the carburetor. He had no more trouble.

I have s single cylinder Briggs and Stratton push mower that unfortunately never seems to have problems–I would like to have an excuse not to mow my lawn.

Hmmm. Rebuilding these is really fairly straight forward. The only thing different is the float valve seat that is pressed in. You have to use a self tapping bolt to put threads in it, then another bolt and spacer to pull it out, then press in the new one.

I’m going to put another new filter on it. When I replaced it a month ago I just took what they had at Ace, but notice the book calls for a different filter for those with fuel pumps. That’s why I like to have some genuine parts on hand since its usually a Saturday afternoon or something when you need them.

I’m starting to develop a real bad attitude about gasoline; especially Ethanol laced gas.

Sine I dink around with project cars at home and some of them may go for months without being started I’ve run into several instances in the last few years of 4-5 month old gasoline going not just bad, but totally bad and to the point where it won’t even ignite. (Stabil did nothing at all to help this.)

The latest incident was a few days ago. The car in question sat for about 2 months and when started the other day it ran very rough. A quick look showed that one of the accelerator pump discharge ports was not spraying gasoline. (new carb)
Pulled the top off the carb and the gasoline (word used loosely) in the float bowls had already gelled.

This gunk was not due to any substance in the tank or lines because not only had the fuel lines been blown out, the tank had also been removed and thoroughly cleaned when a fresh 3 gallons of gas was added 2 months back.

This kind of thing may be the reason that many stations around here are now refusing to carry Ethanol laced gasoline and even advertise the fact out front.

You say “Ethanol laced gas” like you are talking about illicit drugs. Are you a fuel narcotics officer?

When I buy gas for the mowing season (roughly eight months where I live), I add a double dosage of Stabil to my Ethanol laced gas. My mower runs fine. I drain/burn the last of the fuel out of the mower in late November. I get a carburetor rebuilt every 4-5 years. I bought the mower new in 1991.

No, just tired of going through the same old, same old routine. Four or five months is bad enough (and yes, Stabil was added) but 2 months?

It’s a bit frustrating to have to tear into a new Edelbrock carburetor and clean the goo out of the float bowls.
Dump some of this alleged gasoline on the floor, throw a match on it, and it won’t even flash up. Eventually it will start burning slowly much like diesel would.

There’s a growing tendency here for stations refusing to carry Ethanol gasoline and they even have signs posted giving one of the reasons as being what I mentioned.

Consider this.
I hold an aircraft powerplant license and while not a licensed pilot I’ve been at the stick or wheel a few times and that blurb would make me think twice about going up with a tank of that in place.

Since Ethanol gasoline can attract moisture out of the air maybe the locale has something to do with it. Here in OK we have days of near unbearable heat and humidity. Walk outside at 9 in the morning and within 5 minutes you’re soaked with sweat and feel like you just exited a steam bath.