Starts first pull but.....

[sdnative1964]

Then motor surges and lopes as if it's a fuel supply problem. Eventually stops running. Gas is fresh and I know flow is fine at least to carb side of fuel filter. Air filter was filthy but does same thing regardless if air filter is on or off. Removed carb bowl and shot float w/ carb cleaner. No change. Removed air filter housing and douched all accessible carb parts w/ carb cleaner spray. No joy. Right now I'm just short of removing carb assy from intake manifold. What typically acts as the fuel pump for these mowers? Is it a mechanically driven diaphragm type pump? Possibly hole in diaphragm? Once motor gets up to normal operating temp it runs pretty well but I still sense a stagger. It's a approx 2007 Toro with a 6.5 HP B&S motor. No primer bulb, but never needed one anyway. Would appreciate any help possible. Thanks.

 

[Rivets]

Take the float bowl bolt out. This is the main jet. Make sure that the jets are clean in both directions. Suspect the one going up & down is plugged.

 

[sdnative1964]

Did that one, or at least think I did. Carb cleaner shot straight through. Does the position of this orifice, i.e. oriented front o back or side to side when installed make a difference? I did notice that when mower was propped up (front end elevated) it seemed to run better. I know it shouldn't matter but......
Thanks for the suggestion though. I appreciate it.

 

[Rivets]

Does it have a copper float?

 

[sdnative1964]

Does it have a copper float?

NO SIR. Its plastic.

 

[Rivets]

Hoping it was copper. You said it ran better on an angle, this tells me there may not be enough fuel getting in the float bowl. Check to see if fuel runs freely from tank to carb. There is no pump on this unit, gravity feed.

 

[sdnative1964]

Maybe this will help to narrow down possibilities. Starts first pull. No problem. Surges and lopes for several seconds possibly minute or so. Then dies. Let sit for maybe 1 minute or less (I assume while float bowl refills from gravity) and repeats same behavior. After several cycles of this (and much swearing and frustration) it will run but I can hear it just aint right. Just sounds like it should run stronger. I know that's vague but you get my drift. I know this is NOT a commercial machine but it has relatively low hours for it's age. Thanks for any continued assistance.

 

[Rivets]

Either the float needle valve is not opening fully or you have blockage in your fuel line.

 

[sdnative1964]

I think I've isolated this to a problem w/ the automatic choke. After starting the choke never moves from the full choke to normal operating postition. If I manipulate it manually to normal position the motor runs great. What controls the autochoke? Thanks.

 

[Rivets]

The aut-choke is controlled by a thermostat by the muffler. You can check and adjust by removing the shroud and adjusting the metal arm. It should adjusted by bending the metal arm so that it is located between the marks on the plastic air vane arm.