Onto last tiller

David G · Apr 12, 2015

I am onto the last tiller to fix up, this one is a gift for my dad's church.

It is a B&S with the tank under the carburetor. It had 2 issues, lack of good suction and carburetor plugged up. I did a valve job on it today, now it has great suction. It has been sitting for a couple of years and does not have spark now, so that is next. I ordered a spanner and recoil wrench tonight, so will check points and condenser.

I think I lost a check ball in the carburetor, but cannot find it on parts manual, anyone with experience, help is welcome.

Steve@Advance · Apr 12, 2015

Not sure what model you're working on, but most I've seen had the fuel pump diaphragm on the side of the carb. There were a couple of tabs on the side of the diaphragm that served as check valves. No ball that I remember.

Can't you sub a later electronic coil and just abandon the points?

David G · Apr 12, 2015

This is a 5HP horizontal shaft mid 80s or 90s, the carburetor is bolted right onto the top of the fuel tank. It sucks up from the tank and there is a diapghram pump on the side of the carburetor. I cannot figure out how it could pump without a check valve.

David G · Apr 12, 2015

It looks a lot like this.

http://www.searspartsdirect.com/part-number/299437/0071/500.html?utm_source=google&utm_medium=cse&utm_term=299437&sid=SPDxGPROD&gclid=CLal8qSi8sQCFQqOaQodzEYAvQ

Jeff NWOH · Apr 12, 2015

If that is mid 80s to 90s there shouldnt be any points to worry about. I believe 82 or so they went to electronic ignition. Also reasonably sure there arent any check balls in those carb setups. I've never seen one. Just the gasket for the side cover on the Carb that has a couple flaps to act as checks.

David G · Apr 12, 2015

Thanks much

Is the mixture screw for gas or air?

Jeff NWOH · Apr 13, 2015

Mixture screw is for idle mixture. Start at 1.5 turns open. I found this web page that gives a pretty good overview of that carb.
poke here

Geo-TH,In · Apr 13, 2015

If it's not pumping fuel, replace the diafram. The smaller 3.5 flat head briggs had a similiar design on their carbs, tank below carb. Diaframs get old and crack. I just replaced one on an old 3.5 briggs. Your local parts place will have one.

To get the old girls started after sitting over the winter, put a few cc's of gas in the carb. It will start after you get spark. Sometimes rust on flywheel will prevent you from making a spark.

thdrduck · Apr 13, 2015

Also there is a secondary fuel tank under the carb. The system picks up fuel from the main tank and puts it into the little secondary tank where it gets picked up for running. These little BS motors hate water. If you get water in the secondary tank, she will start by putting a little gas down the carb but only run for a few seconds. If you must leave it outside, cover the motor.

Blackhole49 · Apr 13, 2015

The diaphragm is the check valve also. I just ordered them and got 5 for $14 with free shipping. I have 4 different with that same carb. I changed the one on an old ford snow blower I junk picked and even though it looked fine, the new diaphragm solved the hesitation problem.

David G · Apr 13, 2015

Thanks, I wondered what the second pickup was for.

Onto last tiller

David G

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Steve@Advance

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David G

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David G

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Jeff NWOH

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David G

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Jeff NWOH

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Geo-TH,In

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thdrduck

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Blackhole49

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David G

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