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Always Preparing
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Discussion Starter · #1 ·
Hello folks....

I have a 10.5 HP Briggs engine for my ATV mower. The problem I'm having now is follows...

Earlier this year I was able to get the thing running after an adjustment to the fuel air mixture. Now while sitting idle it runs like a champ.. But as soon as I start to move the mower or even rock the ATV the mower engine stutters / loses power. Like I said earlier this year was working fine. Only thing that's changed is fuel in.

I've already taken apart the carb and cleaned it up best I could. I've even moved the fuel tank and raised it thinking that maybe gravity wasn't working well with the designed placement of the tank. No change. Plug was changed earlier this year late last year.

This mower was down for years because the last engine seized up due to water in it as a result of not properly being stored. Great mower that I've had over 10 years now as it helps to maintain my BOL.

Any thoughts from you small engine mechanics?

Dean
 

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The end is,,,,,
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Float in carb may have a hole in it. Governor spring may be weak or gone. They are simple to get running, not much to them. Good luck, keep us posted.
 

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1 Thessalonians 4:11
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I have one word for you... ethanol.
This may be true here.

I know that we have had to replace petty much all of our fuel lines from our chainsaws because of the ethanol in gas.


If you have spark, then it'll be a fuel problem most likely.



Have you cleaned out the gas tank?

Is there a fuel pump on the motor? I know a couple of our Briggs engines on our fire pumps have small diaphram fuel pumps and we have had to replace the inner parts of the pump. It looks like a small rectangular "box" with fuel lines going in and out. The diaphram may be dried out from sitting for so long.

The carb may also be out of tune. Might be running too rich (I think).

Jut brainstorming here - it's hard to do without getting my hands on it.
 

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It sounds like a possible float problem but may also be things like your fuel cap not venting well, fuel line problem or the like. Whatever you do don't mess the the springs controlling your carb. Those springs are calibrated and messing with them is a bad idea.
Good luck.
 

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replace or at the least clean the spark plug and check gap. Clean the ignition and flywheel with (where they line up) scotch bright or light sandpaper, this area can get rusted up. New air filter and oil and run some sea foam thru the fuel system. You can find sea foam at any autoparts or wally world. It will dissolve any gum and varnish in the carb and lines.
Check the engine model number and look on line, you should be able to get stock settings for the carb. The tank in the original location should be fine and check for any cracks in the fuel lines.
 

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I agree with catfish, clean all rust off of the flywheel. They rust up pretty quick and cause you to lose spark. If it was running before and stopped its not the carb adjustment. Unless something changed then it should be fine. It could be a carb problem like a real dirty air filter or water in the gas or even some old gas that turned into varnish therefore gumming up the passages. If it was me I would go buy a new spark plug and be sure its gapped properly, then drain the fuel completely and refill with fresh gas. Then I would check the air filter and clean or replace it. And pull your sparkplug and plug the wire to it and lay it to the side of the motor and pull the cord. You should see a nice fat spark. If not or its weak clean the flywheel using steel wool or a scotch brite pad. If it still wont run good please let us know. These are simple motors and it shouldn't take too much to get it running good.
 

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I am Jody
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Its the float, you have a spark! Sometimes its just easier to order a new carb instead of messing with it. I would brush and gap the plug and replace the WHOLE carb with a new one.
 

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Always Preparing
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Discussion Starter · #12 ·
Wow thanks folks..... o.k. lets see if i can get all this..

New fuel line already..

new plug also but i do have to check it again just in case.

fuel well a few tank fulls have been run through it already so it's not stale or anything. i do have to drain it and check the screen inside. but i've pull the line and let it run through the line and no problems with flow.

No fuel pump on this one - pure gravity thankfully. I've moved the tank higher just to be sure and no change.

Carb: That's where I'm pointing to be honest. I've pulled it apart and there is some rust noted inside on some parts but more a discoloration than anything. Was toying with getting a rebuild kit and going from there. Just have to find the rebuild kit for this particular.

Fly wheel: haven't checked that out yet. I'll have to tear it apart and see what I can see.

Thanks folks.. keep 'em coming.. I so need this mower up and running again like it should be.

Dean
 

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Destroyer of Ignorance
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You said it's a mower that you pull with your ATV? So basically you're just towing a running mower? What I don't understand is that you say "when you move it". Do you mean when you throttle it up or when you start rolling? Forgive my ignorance here, I know a lot about engines I've just never experienced a tow behind mower system and I'm not sure how it's supposed to work.
 

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No fuel pump on this one - pure gravity thankfully. I've moved the tank higher just to be sure and no change.
The fuel is pumped(pulled) into the fuel system by the pulses of the engine. So, moving the fuel tank further away is not necessarily a good thing. It can weaken the pulses pulling the fuel with a longer fuel line. The stock location for the tank is fine and you can hurt performance by moving the tank to far.
 

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Always Preparing
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Discussion Starter · #16 ·
You said it's a mower that you pull with your ATV? So basically you're just towing a running mower? What I don't understand is that you say "when you move it". Do you mean when you throttle it up or when you start rolling? Forgive my ignorance here, I know a lot about engines I've just never experienced a tow behind mower system and I'm not sure how it's supposed to work.
Nope this is a front mounted mower. so I'm pushing a running mower. By moving is I mean I can either shake the ATV which in turn bounces the mower on the mount or moving forward / backward. Throttle stays the same. No adjustments made.

This is the same concept as a tow behind mower but just pushed instead.
 

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Always Preparing
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Discussion Starter · #17 ·
The fuel is pumped(pulled) into the fuel system by the pulses of the engine. So, moving the fuel tank further away is not necessarily a good thing. It can weaken the pulses pulling the fuel with a longer fuel line. The stock location for the tank is fine and you can hurt performance by moving the tank to far.
Fuel line wasn't changed in length. Tank was raised higher with the same length of fuel line as in the original position.
 

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Always Preparing
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Discussion Starter · #19 ·
Not yet.. Haven't had much time to get back to it actually. Working all weekend so maybe next week I'll mess around with it more.
 

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sounds like a fuel problem for sure, i'd check in this order...fuel tank, fuel lines, float bowl and float(check to make sure the float isn't puntured and it is at the correct height), check the main jet(might be varnished up or loose), ensure the idle mixture and speed screws are setup coorectly, ensure the choke diaphram is not pucntured...sounds like when you adjusted the fuel mixture screw you masked the original problem and created another...good luck
 
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