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My John Deere D160 with a B&S 44S977-0001G1 engine surges constantly unless choked at a precise amount. Pouring gas into carb makes it run smooth(er) until the excess gas is used up and then it surges again.
I changed fuel filter, checked fuel lines for kinks and then I removed the carb, cleaned the bowl which had some crusty stuff in it, and spray carb cleaner in a few holes and in the float needle, etc. Same problem. I guess this is a carb rebuild. Before I do that though, how can I check fuel pump for adequate output? What else might I check?

sofasurfer said:

engine surges constantly unless choked at a precise amount.

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Engine is starving for fuel. Carb and or fuel system is dirty.

sofasurfer said:

Pouring gas into carb makes it run smooth(er) until the excess gas is used up and then it surges again.

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Confirms engine wants more fuel slash dirty carb/fuel system.

sofasurfer said:

I removed the carb, cleaned the bowl which had some crusty stuff in it, and spray carb cleaner in a few holes and in the float needle, etc. Same problem. I guess this is a carb rebuild.

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Ah a partial attempt I guess. Not a full rebuild. That would be clean and all new serviceable slash wearable parts/gaskets.

sofasurfer said:

how can I check fuel pump for adequate output

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Take a glass quart canning jar. Scrap piece of fuel line. Maybe connect it to the outlet of the pump. Run the hose into the jar. Maybe crank the engine a coupe times.......... Should have a good fuel flow into the jar.

More tips.

1.KEEP and remove OEM carb from engine. Break it down removing all small parts. Boil clean the carb on your stove top with water and those automatic dishwasher balls. Use a candy thermometer to keep water/soap temp at 200F. Boil for 30 minutes. Rinse well in clean water to neutralize after. Blow out with compressed air. Reassemble carb. Flip carb over and blow test carb needle/seat (fuel inlet pipe). Should hold 7psi for 30 minutes.
2.Remove fuel tank. Clean out 100% with compressed air. Install new fuel line, filter and shut off valve if you have room.
3.Clean block and cooling fins YEARLY per your engine manual. Remove top metal engine shroud exposing cooling fins. Neglect this and you will get engine damage.
4.Adjust valves per your engine manual yearly.
5.Decarbon cylinder and valves every 5 years or suggested interval in your engine manual. Neglect this and you will get engine damage.
6.Test ignition coil with old spark plug gaped to 0.250" or 1/4". Check for good blue spark.

slomo said:

1.KEEP and remove OEM carb from engine. Break it down removing all small parts. Boil clean the carb on your stove top with water and those automatic dishwasher balls. Use a candy thermometer to keep water/soap temp at 200F. Boil for 30 minutes. Rinse well in clean water to neutralize after. Blow out with compressed air. Reassemble carb. Flip carb over and blow test carb needle/seat (fuel inlet pipe). Should hold 7psi for 30 minutes.
2.Remove fuel tank. Clean out 100% with compressed air. Install new fuel line, filter and shut off valve if you have room.
3.Clean block and cooling fins YEARLY per your engine manual. Remove top metal engine shroud exposing cooling fins. Neglect this and you will get engine damage.
4.Adjust valves per your engine manual yearly.
5.Decarbon cylinder and valves every 5 years or suggested interval in your engine manual. Neglect this and you will get engine damage.
6.Test ignition coil with old spark plug gaped to 0.250" or 1/4". Check for good blue spark.

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Very interesting. Good stuff. I'll see what I can do.
Whats a good price for a carb kit?

Ok, I been on youtube studying carb disassembly and boiling. One question. Will boiling remove stuck gaskets rubber seals without damaging them? Just wondering if theres a chance of avoiding a new rebuild kit.

sofasurfer said:

Ok, I been on youtube studying carb disassembly and boiling. One question. Will boiling remove stuck gaskets rubber seals without damaging them? Just wondering if theres a chance of avoiding a new rebuild kit.

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You talking about the carb bowl gasket? I would remove all small parts like needle and seat, float, float hinge axle pin ect... Remove all pilot screws and welch plugs to get behind them for cleaning. Do the best you can. Most of the time that bowl gasket will be stuck on. Sometimes reusable. You will have to clean it and see if it leaks. If it leaks you will need said gasket and maybe not a whole rebuild kit.

Does the surging happen strait away or after an almost fixed amount of time ?

I took the carb apart. No gaskets were damaged. I did not take the butterflies out. I did not remove that little 4 hole gasket in the center inside the bowl location. I sprayed carb cleaner through all the holes. Nothing was plugged. Only corrosion was in the bottom of the bowl. Reassembled and installed carb. No more surging. WAIT! Don't get excited. Now it is running rich. It runs pretty smooth at low idle. I can increase rpms a little and there is no surging. If I slowly increase rpms it sputters and will run rough and smoke. If I just shove it into full throttle it sputters real bad and stalls. So I made progress but...
Any thoughts on this?

Pounds to peanuts that the main jets have come loose
Whenever one of these carbs come apart they need all of the gaskets & O rings replaced
In particular the main jet O rings
And you need to lube them before installation or they will not go fully home
Most times the jets fall out when you remove the tube
Parts 117 in the B & S parts list for your mower

I was not familiar with the jets yet. I haven't messed with this stuff since the 80s. Are you saying the jets are still where they should be but became unseated during disassembly? I'll go find a video about them.

O boy! Both jets are missing. there's a definite Einstein invention...jets than just lay there with no securing function.

Lucky me! I got out the old trusty metal detector and found the jets in the grass right next to each other. Both o-rings are in place. Now, are they both the same or is one the left and one the right? I found a "12" on one but the other seems to have nothing on it.

Could not see a differance in the jets through a magnifier so I just installed them. Tractor runs like a Deere. Not bad for a true backyard mechanic and it didn't cost me a cent. Learned a lot too.

Double check, they are a bit hard to see
And yes they often fall out which is why I mentioned it
he O rings are quite a tight fit when new but flatten over time and can be adversely affected by some fuels
go to Out door Power Info and check the photo tutorial about cleaning your carb
If you blw it out with any air above 5 psi then order new ones as yours will be in low earth orbit right now .

Get yourself a rebuild kit and keep it handy
Once disturbed those jets will continue to come loose but at least you know now
if you troll through the forum searching Carburetor O ring
the size of them has been posted several times
I bought a bag of 200 near a decade ago for peanuts but they are a common size held by most engineering / bearing / tool shops ( not HF or Lowes )

bertsmobile1 said:

go to Out door Power Info and check the photo tutorial about cleaning your carb

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Thats a pretty good site

Thanks all of you