Briggs and Stratton 17.5 I/C OHV

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  #1  
Old 09-29-12, 04:51 PM
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Briggs and Stratton 17.5 I/C OHV

Model Type Code
31C707 0175E1 040722ZD

Ok when I started this project the mower wouldn't fire off, so I by-passed the seat-switch,new spark-plug, wirewheeled the crank and coil and cleaned the carbarator. Now I have spark and it fires off but stalls when i try to take it out of the choke position or put it in gear.

Any Help would be greatly appreciated the Wifey has put me on fishing restrictions until i get this yard mowed and I'm to hard-headed to take it anywhere. Thank You
 
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  #2  
Old 09-29-12, 07:34 PM
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If it sits and runs until you take off the choke that's fuel = carburetor (cleaning) or before the carburetor = fuel pump, fuel line to carb, plugged fuel tank - that sort of thing,

Tell your wife to lighten up a little, If nobody fished, there'd be way too many fish.
 
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Old 09-29-12, 07:59 PM
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The fuel line goes from the middle of the gas tank bottom thru a line into a filter which is clean and straight into the carb and i cleaned the carb already the gas in the tank is clean. So there is no fuel pump and the fuel lines are good. There is a sensor of some sort on the bottom of the bowl that has a wire running to it maybe that could be it?
Thanx for the input much appreciated, I know very little about small engines so every input is very valuable to me.
 
  #4  
Old 09-29-12, 08:32 PM
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That's a fuel shutoff solenoid. Pull it off, ground the outer casing and feed it current to see if it's opening and closing. That could be a problem.
 
  #5  
Old 09-29-12, 09:51 PM
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Ahhh ok so that solenoid kinda acts like a bladder?....right on thank you i will try that first thing in the morning
 
  #6  
Old 09-30-12, 05:55 AM
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The purpose of it is to prevent a backfire from going back into the fuel tank. Not all engines have them.
But if it isn't opening fuel won't get into the float bowl.
 
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Old 09-30-12, 10:20 AM
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what would be the best way to ground the casing?
 
  #8  
Old 09-30-12, 02:53 PM
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Just hold it tight against the carburetor (metal) or the engine fin. It typically grounds where it mounts into the carburetor.

Just make sure it has good contact.
 
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Old 10-02-12, 11:23 PM
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sorry it's been raining here for 2 days. But it is working what should I try next?
 
  #10  
Old 10-03-12, 07:07 AM
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quote The purpose of it is to prevent a backfire from going back into the fuel tank. Not all engines have them.
But if it isn't opening fuel won't get into the float bowl. endquote

That's not my understanding of it. It's an anti-fire solenoid. There is not fuel flow through it . It will not stop fuel from entering the bowl and it will not stop carb from flooding. It has a plunger , which when the solenoid is deactivated moves up and blocks fuel flow from the bowl to the main jet. Idea is that when spark is removed to stop engine , the engine continues a few rotations with no spark. In these rotations fuel would be drawn into the cylinder and exhausted as unburned into a hot muffler which would ignite it in a big bang. By having the plunger stop the fuel into engine at same time as spark is stopped should prevent the big bang, in theory.
 
  #11  
Old 10-03-12, 10:06 AM
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That is correct 38racing.

It sounds like the carburetor is still clogged on this engine. It needs more cleaning.
 
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Old 10-03-12, 02:46 PM
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I'm not having trouble with backfiring, when i try and pull the lever out of choke position into fast or slow positions it stalls same when i try and put it into gear or engage the blades
 
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Old 10-03-12, 03:21 PM
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Yep, that's why I say it needs the carburetor cleaner more thoroughly.

We're neighbors by the way...
 
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Old 10-04-12, 05:51 AM
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That makes sense 38racing. But the solenoid, if not working properly can cause his problem if the fuel is not allowed to enter the main jet from the float bowl.
 
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Old 10-04-12, 08:42 AM
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That makes sense 38racing. But the solenoid, if not working properly can cause his problem if the fuel is not allowed to enter the main jet from the float bowl.

I don't think so , because if the solenoid is not opening it will not start or run at all. He's got it running but too lean. The solenoid I expect is usually an all or nothing although I guess if the tip has crud on it there could be a lean condition created.
 
  #16  
Old 10-04-12, 08:52 AM
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It would run through the idle circuit. And with the choke applied it would increase the volume through that circuit.
 
  #17  
Old 10-04-12, 10:12 AM
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No, it won't run if the solenoid is closed. The solenoid closes off the pickup tube so that no circuit is fed by the fuel in the bowl.
 
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Old 10-04-12, 10:23 AM
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K. So it's not just shutting off the main jet.
 
  #19  
Old 10-04-12, 10:29 AM
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the carb. is clean as a whistle.........
 
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Old 10-04-12, 10:32 AM
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could it be that I by-passed the seat switch?
 
  #21  
Old 10-04-12, 10:43 AM
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If it's running, but only with the choke, then you take off the choke and it dies, that would be back to fuel delivery and, as Cheese suspects, dirt in the carburetor somewhere. There is a remote chance of a weak ignition, but more likely fuel.

If everything is running well and it dies when you engage the blades, that is likely a safety switch (the seat switch or another one).
 
  #22  
Old 10-04-12, 10:36 PM
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I agree, the seat switch bypass attempt (I say attempt because these are designed to not be bypass-able) could be the problem with the shutting down when you engage the blades. It doesn't have anything to do with it running only with the choke on though. It's a carb problem.

marbobj, it does shut the main jet. The main jet is in the bottom of the tube that extends from the bottom of the carb, where the solenoid screws in and holds the bowl on. The idle circuit is higher up than that and it gets it's supply of fuel through the main jet first. All fuel goes through the main jet, then gets distributed to the venturi jets and idle circuit.
 
  #23  
Old 10-05-12, 02:58 AM
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Thanks Cheese. That's what I took it to mean when you said it blocks off everything. I have my faithful Wheelhorse/16 horse mower that gives me a big bang when I shut it off - about 75% of the time. It could use one of those solenoids.
 
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