Lawn mower question

[supton]

Look at where the carb meets the intake pipe. Is there a gap there? It kind of looks like entirely the wrong carb for this engine. Also two attachments to the choke lever -- someone has been doing a lot of tinkering.

Don't know what is going on with the choke attachment--it goes off to a factory looking rod, that goes nowhere. I almost think it was meant to knock it off choke when a user goes from low throttle to full, but so far, haven't figured it out. Might have been messed with, don't know yet.

The gap is an illusion, it's sealed.

 

[supton]

Not sure if that is the right carb now that I look at the pics, but here is a link to the correct one:

Amazon.com : Briggs & Stratton 799727 Carburetor Replaces 791886/698620/690194 : Lawn And Garden Tool Replacement Parts : Patio, Lawn & Garden

Amazon.com : Briggs & Stratton 799727 Carburetor Replaces 791886/698620/690194 : Lawn And Garden Tool Replacement Parts : Patio, Lawn & Garden

www.amazon.com

Thanks.

But what is the electrical connection for? Mine does not have that. Side view of mine:

That Amazon carb, and many many of the ones on Ebay (if not all!) have this electrical connector.

 

[mk378]

The rod with a loop at the end is the factory choking mechanism. The factory setup does not have a separate choke control or choke cable. When the speed control lever is pushed beyond "fast" (pulling the plastic slider block all the way back), a lever swings up and pushes on the end of the loop. This pushes the rod forward and the choke plate closes. After the engine has started, the operator would move the speed control back from "choke" to run at the desired speed.

It still looks like the flanges don't match. Is the bore size the same between the carb and the intake?

The solenoid would cut the fuel off to prevent after-running when the key is turned off. The solenoid needs to be energized with 12 volts from the battery to let the engine run. This is not something you need-- you would have to add wiring for it so it would be better to find a carb that does not have a solenoid.

 

[supton]

I will take a look at flange issues--but as long as it's sealed I don't see why it'd have issues. It's not a hot rod, after all.

Makes sense on the choke rod. Ok, I see how you mean it was jerry rigged now. This is an older mower and the choke lever appears to be original, so PO must have modified things to remove the embedded choke feature that newer engines use. Still, small change.

Ok on the solenoid, I guess technically I could solder wires up for that, but it'd be easier to not to. I'll have to mess around first to see about getting the carb off, those bolts are tricky. I might have to double nut it.

 

[jeepman3071]

Thanks.

But what is the electrical connection for? Mine does not have that. Side view of mine:
View attachment 29316

That Amazon carb, and many many of the ones on Ebay (if not all!) have this electrical connector.
View attachment 29317

You can swap the bowl nut on your old carb in place of the solenoid. I think in later years, most of those carbs came with the solenoid so they include it on many of the aftermarket carbs. I've replaced the solenoid with a regular bowl nut many times, and the bowl nut on your old carb should be a direct swap.

 

[supton]

Ok, thanks, I might get one on order then. I've had the fuel bowl off a couple times already and it's clean, no gunk in there.

Dawned on me this morning, maybe when it flooded out and I pumped it out the first time, maybe the intake manifold was still flooded and that is why it flooded a second time--it hadn't fully dried out. Dunno. I should give it another try today.

I still don't understand why the dipstick has to be in place while running, I still think something is off, but not sure what.

 

[supton]

Ran ok this weekened--did nothing but put back together. And made sure to turn off the fuel cutoff when it wasn't running!

When cold the dipstick seems to have no effect on running--when good and warm it does bog down a bit, but it did not die. When the motor is hot and I cut throttle from high to idle, it will puff a bit of blue, so I think the rings are probably worn. I did change the oil, and it was kinda nasty looking. Thin, grayish material in it. Hope for the best, plan for the worst: hot idle sounded like it has a rod knock or something... Someone has been in the bottom end (lots of RTV attest to that) so who knows.

It was cutting good but then a spindle went out. Can't win!

 

[borgward]

Am I missing something? Bogs down with out the dipstick. Is the dipstick missing. If so get one if possible - you will need one anyway. If not available find some way to plug the hole to see if it runs ok like that.

 

[gathermewool]

Can’t win? This thing is 30 years old!

 

[gathermewool]

Am I missing something? Bogs down with out the dipstick. Is the dipstick missing. If so get one if possible - you will need one anyway. If not available find some way to plug the hole to see if it runs ok like that.

Gotta read the thread posts, my man. He has a dipstick. It bogs down the engine when warm with the dipstick removed.

 

[supton]

Can’t win? This thing is 30 years old!

Like I know, really! Ya spend a hundred big ones and whaddya get? Geez...

 

[toneydoc]

Crankcase pressure may drive a fuel pump
That is the way my B and S engine works

 

[Kamele0N]

Yup....that engine must have that pump wich operates on pulses from a crankcase....

 

[mk378]

These single cylinder flatheads were typically on low price mowers, so another cost-saving measure was a gravity flow fuel system using a necessarily small (1 or 2 gallon) tank mounted under the hood above the level of the engine. Thus if the float doesn't close the fuel will keep flowing until the tank is empty, and a shutoff valve is a really good idea (though also omitted from original equipment for cost). With a bad needle valve the bowl may even overfill while running, especially at idle or with no load (fuel consumption less than the leak rate)-- and this will cause a flooding out, i.e. "bogging" effect.

Seriously quit worrying about dipstick in or out. I've never tried to run one without the dipstick neither should you.

 

[borgward]

Gotta read the thread posts, my man. He has a dipstick. It bogs down the engine when warm with the dipstick removed.

So why is he removing the dipstick while it is running? Runs ok with Dipstick in?

 

[Silverado12]

Nikki carburetors are problematic. I think your issue is with the float valve. I had to rebuild the one on my 1 year old 17.5 B&S rider and it flooded the motor with gas also. I also installed a shut off valve on toe fuel line.

 

[Silverado12]

Oh and I have seen the float pin that will only come out one way.