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Hard Starting push mower

Posted by exmar 6 SE Ohio (My Page) on
Tue, Aug 9, 11 at 16:16

Briggs 92500 series on an old push mower that I only use for trimming.

rebuilt carb, new plug, strong spark, good gas (with stabil and stp carb cleaner added), clean air filter, choke works fine,etc. etc.

This thing is a bear to start, but when it does, it runs strong, idles down and keeps idling, and runs well at any position between idle and wide open.

I'm sure I'm missing something, but I can't find it. Probably a case of overlooked it the first time through and it's now invisible....:-)

Ideas appreciated.....

Thanks for your time,


Follow-Up Postings:

RE: Hard Starting push mower

Sounds like you have all the elements, fire, fuel and compression since it runs good at all speeds. You are possibly not getting something at the right time.

1. What is the history or the initial problem?? Approx whar year model, electronic ign vs points?

2. You checked the flywheel key for damaged X throwing the timing off? Does it ever snatch the rope?

3. You primed carb or plug/cyl to know fuel is there? Did you soak the carb an hr in carb clner w/o jets?

4. Is the fire blue and will jump a 1/4th" gap?

5. Is a bowl with a float on the carb? Is the needle not sticking? Is the bowl's nut orfice hole clear?

6. Do you feel the Carb mixture screws are clear and adj properly (gen seat and back out 1-1.5 and adj running)

I know the feeling and it's usually looking at you. LOL! loger

RE: Hard Starting push mower

Hey, Leatherneck, is the engine old enough that it has condensor/points? If so, did you replace?

RE: Hard Starting push mower

If the engine has points and condenser you have two good options IMO.

1. If the Crank seal is not allowing oil into the ignition area, clean or replace the old points and regap @ .020

2. If oil blow-by is contaminating points, adapt the electronic module to replace points/condenser, they work great.

I saw a link on the electronic module below but check and compare your local shop's product/price also (if needed). Open and scroll down to Brigg & Stratton Magnetron Kit.

Good Luck! jow

RE: Hard Starting push mower

  • Posted by exmar 6 SE Ohio (My Page) on
    Thu, Aug 11, 11 at 8:46

Great ideas, only, no points. I may, however, shine up the side of the flywheel and check the gap to the Armature, or is it called a magneto on these?

History is that it's always been a good 3-4 minute hassle to start, it was given to me about 10 years ago "dead." I got it running again, new gas, clened out carb and a new plug. I rebuilt the carb last summer thinking that may have something to do with it and it didn't.

Loger, the answer to all your questions are yes, except I didn't soak the carb for an hour in cleaner.

I can live with it, it's just the only small engine I have that doesn't start right up.

Thanks for the ideas,


RE: Hard Starting push mower

Appears that it is not picking up enough fuel immediately . Old Style Gillotine chokes were often less than instant starting units. Any small restriction within the fuel circuit and more than a few pulls were required. If you had a primer / purge bulb as is the norm with newer units you would not be experiencing the problem . How ever older units had this common issue as they got older (weaker) . As a secondary unit as you have said it is earning it's keep .

RE: Hard Starting push mower

1. If you use a syringe etc to prime the carb will it start easier? If so, why not drill a 1/16 - 1/8" hole to prime through and plug it after it starts? Is there a universal primer button kit to add on old carbs?

2. Do you know of a link to your carb? I would like to know we are connecting related to the bowl's nut orfice hole being clear. If you are not experienced, it’s easy to miss and it might just affects running vs starting??

3. I hate to see an engine work you before you start your jobs. I always tell my friends if it d/n start by the 5th pull, “STOP”, You Have A Problem!

Take care! loger

RE: Hard Starting push mower

If the spark plug is dry when you try to start it without priming My best guess would be it's not pulling gas up through the carb.

Two things to check would be the down tube screen that sets in the dished area of the gas tank. Some times this screen sets in water and will rust reducing the suction.

another thing to check is the diaphram in the carb. that pulls the gas up through the carb. when you pull the rope. Also the o-ring on the carb. outlet tube maybe alowing air to be drawn in and it won't pull the gas up to the comb chamber.

Last I would go over my procedure of assembly make sure I didn't forget something especially if it started before your overhaul?

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