# Briggs and Stratton fuel issue



## mjed0 (Jul 17, 2011)

I have a briggs and stratton 450 series 148cc lawnmower. 2 1/2 years old. I cut the lawn last in November and now it won't start after the 3ish month break. I sprayed starting fluid in the cylinder and it ran for the typical 1-2 seconds you expect, tried spraying straight in the carb next with same 1-2 second running result. I then poured a tad of gas in the carb, again ran for 1-2 seconds and dies. The gas I poured in the carb is the same source as the gas I filled the tank with, although the gas in the tank has been in there since November. 

Is 3 months enough for the gas to go bad in the mower tank? Or could I be looking at another reason why the fuel may not making it from the tank and through the carb to keep it running? Also, I primed the bulb repetedly to no avail.

Also worth noting, when trying to run it today I started it for that 1-2 seconds about 8 times. After that I noticed black oily liquid dripping out the muffler, could that be excess from floooding the carb a few times with the gas?

Any suggestions appreciated.


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## AVB (Nov 28, 2014)

Could be but I would check the oil level now. It sounds like the float needle valve is struck from gumming fuel residue. If the needle frees it could stick open causing the engine to flood the crankcase with fuel diluting the oil and then oil could run out the muffler.


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## mjed0 (Jul 17, 2011)

Thanks for the reply, yes I'll definately check the oil just in case. But I was putting quite a bit of gas down the carb, so won't be surprised if it's that. As for the starting, I'm wondering if it's rubber O rings or something. I've read about those online but not sure it that applies to the 450 series engine, also could rubber rings already go bad on a 2 1/2 year old engine?


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## AVB (Nov 28, 2014)

I don't know the fuel in England but with today's fuels here in the US anything is possible. I have carburetor completely gummed up in a few months of none use. I have seen rubber components to swell, harden and a few to turn to mush because of fuel and it additives.


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## wristpin (Oct 24, 2014)

Three months (ish!) is plenty of time for the fuel to go "stale" and gum up the carb. Your oily residue from the muffler is just the excess fuell washing out the carbon etc. While doing that it will also be washing the lubrication off the cylinder bore!
Its a valid point that has been made re contamination of sump oil so the sooner the carb is sorted the better.
You may be able to clean the carb with a proprietary aerosol of carb cleaner but if that doesn't work it will be a trip to someone with an ultrasonic cleaner. 
Just may be worth pricing a new carb - note the model, type, and code numbers and letters stamped into the engine cowling and key them into an on line parts list .


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## mjed0 (Jul 17, 2011)

Thanks for the suggestions. I'm going to get a can of carb cleaner today and hopefully that sorts things. Next step if that doesn't work is taking a look at any rubber components and see what they look like. Thanks again.


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## mjed0 (Jul 17, 2011)

*Re: Briggs and Stratton fuel issue 450 series*

Just to update, I have now replaced the fuel, cleaned the carburetor with carb cleaner, cleaned filter on the pickup tube, put a new carb gasket and diaphragm in, cleaned off the air filter (though it was fairly clean still), checked and changed the oil (wasn't contaminated), cleaned up the spark plug and cleaned out the gas tank. It's all back together and I'm very satisfied with how it all went back together and how clean it all is, yet the exact same symptoms persist. I can still get it to run for a second or two with a shot of starting fluid or gas but won't run on it's own accord. I experimented by starting it by pouring a bit of gas in the carb, once it started I quickly continued trickling gas into the carb and ran it that way for about 30-40 seconds until I stopped pouring, then the engine died immediately. For some reason it won't pick up fuel from the tank below and keep running.

Rather frustrating, any other suggestions appreciated.


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## wristpin (Oct 24, 2014)

Somewhere in your carb there is still some gum or worse, some corrosion caused by water absorbed by the ethanol in the fuel - ethanol being hygroscopic. You can try another thorough clean with carb cleaner but an ultra-sonic clean stands the best chance of success. Failing that, it's new carb time.


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## AVB (Nov 28, 2014)

I look-up these engines by the model numbers and not the series. but after re-reading the posts I think you got a Pulsa-Prime carburetor. So this your carburetor?










I don't see this too often but if it won't prime the primer check valve may be stuck open. This is behind the primer bulb. It consists of rubber seat and a spring loaded steel ball. I have these steel ball rusted and sticking open and carburetor can not prime.

Here is some instructions of repairing these.
Disassembly, Cleaning and Repair of Briggs and Stratton Tank-mounted Pulsa-Prime Carburetor


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## mjed0 (Jul 17, 2011)

AVB, thanks so much for your detailed response, but at last the problem is sorted. While I changed the fuel early on in this problem, it was from the same jerrycan. I only filled the jerrycan last November and it's been stored in the shed with mild weather for that almost 3 months, yet it appears the fuel went bad. I have seen gas last well over a year in a jerrycan so this really surprised me. I can understand it going bad within the tank, lines and carb of a mower, and even then 3 months seems quick, but I'd never guess a jerrycan full would go bad in such a short time.

Anyway, long story short...new gas and it's starting and running great. I think all the cleaning and servicing hasn't hurt matters anyway, it's like new now!

Thanks again for everyone who offered advice, much appreciated. :thumb:


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## AVB (Nov 28, 2014)

Don't feel bad at least you found it before ordering any major parts. Once I purchased 5 gallons of fuel while I was tilling my garden. The tiller ran out so I refilled the tank. I didn't even get 10 feet before the engine shut down and a Troy-Bilt Horse is not that easy to get out tilled ground. Pulled the carburetor's fuel bowl and it was full of water then drain the fuel tank again nearly full of water. I then poured the fuel that I just purchased into a clear container. It turned out I had got over two quarts of water in the fuel I just purchased. On that Jerry can make sure it air tight seal as if your fuel contains Ethanol it will attract moisture from the air easily.


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## mjed0 (Jul 17, 2011)

Thanks again AVB, now I don't feel so bad, I expect getting that tiller out of the ground was a workout! As for the jerrycan, I got a new one for the new fuel and the only parts I bought was the gasket/diaphragm for the carb, so all should be good now. :grin:


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