[Peter_S]

I have an old Simplicity 6500 series with a Briggs twin, vertical shaft engine.

Model is 402707 and the code says it was built in '88.

At the end of last season I was having some issues with this old mower and never quite got them resolved.

When I got it going this year it was still surging at idle but evened out with some choke. I checked the carb float adjustment which was definitely wrong. I readjusted the float to be as level as possible with the carb body, put everything back together and now it won't start at all. If I spray carb cleaner into the carb it will run for a second or two and then die.

I pulled the carb again and checked that the float and needle move easily.

I checked the fuel pump diaphragms weren't torn, (they were new at the end of last season and looked fine. No pin holes or tears that I could see.)

I also made sure that fuel was flowing freely from the tank fuel line before hooking it up to the fuel pump.

I can blow through the vacuum side line that runs from the fuel pump to the engine so I know that isn't blocked.

Even though fuel is flowing from the tank side line, there isn't a drop of gas in the carb bowl.

Should the bowl fill from gravity or does it depend on the fuel pump to draw it through?

I'm stumped. I'd really appreciate some other suggestions that I could try.

ADDED: I did check the solenoid too - I can can hear it click and I see the shaft move when I turn on the ignition.

 

[LReeder]

If you disconnect the fuel line from the carb and turn the engine over, do you get fuel pumping out of the line?

 

[RED-85-Z51]

This engine has the fuel pump built into the carb, so there is no hose/line ot test from.

ID start by manually (with your palm) choking the carb while itsd cranking and see if some ubstruction isnt freed by the vacuum it creates...

 

[Peter_S]

If I disconnect the fuel line from the tank to the carb fuel will run out freely. This what is so confusing to me. Even though gas flows free, when I connect it to the carb/fuel pump and turn the engine over there is absolutely no gas in the carb.

While the battery is recharging I pulled the solenoid out and put some pressure to the gas tank thinking there might be an air lock - nothing.

 

[Peter_S]

Thanks Red - I'll give that a try.

This might be a really stupid question since (I'm 99.9% sure) I connected the fuel supply and vacuum line exactly the same way as they were when I removed the carb, but is there any possibility that I have them wrong?

This is a 3 screw fuel pump. I can blow into the side port but not into the lower port.

 

[Walt 2002]

" can blow through the vacuum side line that runs from the fuel pump to the engine so I know that isn't blocked"

The vacuum line to the fuel pump is out the BOTTOM of the fuel pump, not out the side, common mistake. If connected properly, are you sure the vacuum line isn't cracked, leaking?

Walt Conner

 

[RED-85-Z51]

bottom port is the pulse line to the block, the side port is the feed to the pump, and directly into the bowl/needle.

 

[Peter_S]

Okay - this is really embarrassing. Let me go see what happens when I connect everything the RIGHT way.

 

[Peter_S]

Well, how about that! It works great when you put things back the same as you took them apart.

Walt and Red, thanks for replying and setting me straight. She runs great now.

 

[CityFarmer]

Well, how about that! It works great when you put things back the same as you took them apart.
.

After 4 decades of hobbying with small equipment, I still struggle with that concept!:sidelaugh