C 135 International Carb problem

[Daverd435]

This motor is in a Worthing Air Compressor but its just a tractor motor. The problem is the motor starts reeves up runs about 10 seconds at high idle then floods the engine and kills it . Rebuilt the carb and lowered the float trying to lower the amount of gas but it still floods out. When you restart it it runs on two cylinders then three then all four for about in 10 seconds it floods itself out again. Any help would be great thanks. Its a Zenith 389373R92 Carb

 

[Fritz Maurer]

Do the compressor and the engine have separate air filters?

Does the compressor unload at the end of 10 seconds?

 

[Daverd435]

Do the compressor and the engine have separate air filters?

Does the compressor unload at the end of 10 seconds?

Yes they share the same air filter but I have the intake hose off the carb. I have the air valve wide open dumping all the air.

 

[Fritz Maurer]

Close the supply valve and let it build pressure, to make the engine idle, to see if it does the same thing. Is it gravity flow or does it have a fuel pump?

 

[used red MN]

Is the carb holding gas when the gas is turned on or is the float needle allowing gas to leak past? I don’t know Zenith carbs that well do they have the leak off drain if it is over choked? Since the air intake tube is off does gas ever run out of there when the gas valve is open? Maybe this application uses a fuel pump? In that case the float needle would only leak by when the fuel pump is pumping.
(I typed this last night and didn’t hit the post button. I had to redo it from info in your reply 3. That is why it repeats Fritz’s mention of the fuel pump)

 

[Daverd435]

Is the carb holding gas when the gas is turned on or is the float needle allowing gas to leak past? I don’t know Zenith carbs that well do they have the leak off drain if it is over choked? Since the air intake tube is off does gas ever run out of there when the gas valve is open? Maybe this application uses a fuel pump? In that case the float needle would only leak by when the fuel pump is pumping.
(I typed this last night and didn’t hit the post button. I had to redo it from info in your reply 3. That is why it repeats Fritz’s mention of the fuel pump)

It has a fuel pump and no it don't leak when not running. No leak drain off that I know of. Thanks for the reply.

 

[used red MN]

It has a fuel pump and no it don't leak when not running. No leak drain off that I know of. Thanks for the reply.

Are you trying to get it running for the first time under your ownership or have you seen it run before with this carb? Have you went through the ignition checked the points etc.? Once plugs have ran in a flooded condition they don’t like firing correctly again without cleaning or running in a correctly tuned engine at running temp for a while.

 

[Fritz Maurer]

When a freshly rebuilt carb fills initially the float needle is wide open, and the fuel velocity is high. This may wash foreign materials into the carb that would normally settle out in the quiet areas of the fuel system.

Based on what you have stated so far, I would guess you have washed dirt into your fresh rebuild, or the float is sinking. That is, if flooding really is what it is doing, and not actually running dry in 10 seconds.

Remove the drain plug and procure a 1/8 " hose barb fitting and a piece of clear vinyl tubing, and hold the tubing up vertically alongside the bowl and start the engine. If the bowl continues to fill until the engine quits, then the float apparatus is simply not controlling the fuel .... which means dirt or damaged parts.

 

[Daverd435]

Are you trying to get it running for the first time under your ownership or have you seen it run before with this carb? Have you went through the ignition checked the points etc.? Once plugs have ran in a flooded condition they don’t like firing correctly again without cleaning or running in a correctly tuned engine at running temp for a while.

I've owned the air compressor for about 25 years and only use it to sand blast and blow out sprinklers in the fall. it's always started and run good this is the first time it has done this. We have had the carb off and opened up three time checking if something else wrong. I'm familiar with fuel fouled plugs my 91 Harley would foul plugs every now and then. Put all new plugs, wires, cap, rotor, condenser.

 

[Daverd435]

When a freshly rebuilt carb fills initially the float needle is wide open, and the fuel velocity is high. This may wash foreign materials into the carb that would normally settle out in the quiet areas of the fuel system.

Based on what you have stated so far, I would guess you have washed dirt into your fresh rebuild, or the float is sinking. That is, if flooding really is what it is doing, and not actually running dry in 10 seconds.

Remove the drain plug and procure a 1/8 " hose barb fitting and a piece of clear vinyl tubing, and hold the tubing up vertically alongside the bowl and start the engine. If the bowl continues to fill until the engine quits, then the float apparatus is simply not controlling the fuel .... which means dirt or damaged parts.

Had the carb. off and apart three time checking float setting and anything we could find nothing looked wrong. Tired of taking it apart for nothing. Order a new carb should be here next week. Thanks for the reply

 

[used red MN]

Put all new plugs

Just FYI, new plugs even running 15 seconds under flooding conditions as you described will be back to this point.

Once plugs have ran in a flooded condition they don’t like firing correctly again without cleaning or running in a correctly tuned engine at running temp for a while

So they need pulled and cleaned.

 

[BarnyardEngineering]

What makes you think it is flooding? Normally if these updraft carburetor tractors flood they will drip fuel on the ground from the carburetor. The engine should smoke black briefly before dying. The plugs should be sooty and/or soaked with gasoline when you pull one immediately after it stalls. Do any of these symptoms sound familiar?

 

[Daverd435]

What makes you think it is flooding? Normally if these updraft carburetor tractors flood they will drip fuel on the ground from the carburetor. The engine should smoke black briefly before dying. The plugs should be sooty and/or soaked with gasoline when you pull one immediately after it stalls. Do any of these symptoms sound familiar?

What makes me think it's flooding is it drips gas on the floor, black smoke when running , sooty on plugs when pulled, gas smell in shop you can't breath, when putting my rubber glove in front of the air intake in 5 seconds it's wet with gas.

 

[Janicholson]

Welcome to YT forums and PartsASAP.
The flooding could also be the result of a loose or misthreaded needle seat. Jim

 

[used red MN]

when putting my rubber glove in front of the air intake in 5 seconds it's wet with gas.

Do you mean holding your glove over the carb opening? If so this would instantly cause gas to pull into the carb, I suspect you know this. This must mean you are holding your glove “close” to the carb inlet, not sure what that might tell you. It usually means a valve is sticking or one valve is not opening such as a bent push rod or broken rocker arm. I think Fritz’s suggestion in reply 8 using the clear tube to diagnose if the fuel level was a problem in your carb would have been very beneficial information. You chose to pull the trigger on a new carb. If you bought a low dollar replacement carb good luck, seems to be about a 50/50 chance of getting a good one.