Now I have a problem

[SpringHollow]

if the engine was used with non-ethanol gas and now with ethanol, it would not be unusual for a load of crap to get dislodged and plug up things. I hate ethanol gas.

Ken

 

[Kent]

I think the problem is flooding.

I have the fuel injected 28 hp Subaru Robin in my PT425 and have been having the problem lately of what I think is a weakening fuel pressure regulator that is built into the FI throttle body. As far as I can tell there are no schematics, rebuild instructions, or replaceable parts for the throttle body. On hot restarts half the time the engine floods and won't restart. So I have learned to "simply" shut off the fuel petcock I had installed under the gas tank, crank a few times, and it starts right up. Open the petcock after the engine catches, and I am good to go.

I used to think it wise to turn the key and pause for a second to let the fuel pump get up to pressure at the throttle body on cold starts, and that worked for many months, but now all that does is flood the engine. There is just too much gas in the cylinders at startup, both cold and hot.

So rather than turning the petcock every time the engine floods I am contemplating mounting a switch on the dash to control the power to the fuel pump, turning it off until flooding is cleared.

The non-FI Robin has a the vacuum powered fuel pump. I am thinking a normally open solenoid valve inserted into the "pulse pipe" between the fuel pump and then engine would do it. Search EBay for "1/4 inch NORMALLY OPEN 12V DC Solenoid Valve" for samples. Also install a 12v switch to control the solenoid.

 

[MossRoad]

I know my Kohler floods easily, especially if the air filter gets dirty. It happens on hot starts if I shut off the machine for 10-20 minutes after long usage. When I try to start it, it floods. I know the air filter is dirty, so I clean it, then crank it with the throttle all the way off until it starts to sputter, then increase the throttle until it starts.

 

[Digger 258]

I thought it might be flooding at first, so I took off the air cleaner and cranked it a bit. after about 20 minutes of trying different throttle/choke arrangements, I went into panic mode and started checking the fuel pump, spark and compression. I hope when I get home tonight I crank it over and it just fires right up . . .that would be nice. But I suspect there's a problem with the carb. I'll post what I find out.

 

[cqaigy2]

If it's flooding, the spark plug will most likely be wet. While you have the spark plug out, double check for spark.

 

[Digger 258]

when I hold the spark plug against the head bolt and crank, I get a big fat spark. I have fuel spitting out of the fuel line downstream of the pump. I have 85-90 lbs of compression. I figured it's gotta be the carb. When I got home, I charged the battery, checked for spark again, and sprayed some carb cleaner right into the cylinder through the plug hole - then put the plug back in and tried to crank. Nothing.

So I started taking the carb off. When I got the carb off, I noticed a bit of fluid in the intake manifold. The carb was filthy on the outside. Took it to a clean bench with lots of tupperware containers . . .

 

[Digger 258]

The carb was so dirty on the outside, I was convinced something was sticking in there. I took off the accel pump on the bottom and separated the main carb body to get to the floats. It appears immaculate in there! I am completely stumped. I guess I should clean out the carb really good with fluid and air, and put it back together to see what happens. I'm not sure what the electrical component is on the carb that I had to unplug, or if it has any bearing on my problem. Haven't searched the engine manual yet though. (and because Murphy rules, I "temporarily parked" the PT in front of other vehicles I need to move!) It's gotta be either something tragic, or something simple . . .

 

[MossRoad]

That electric component may be your fuel shutoff solenoid.

 

[woodlandfarms]

The thing about a carb is that all it takes is something small... Really small. I would do the teardown just for good measure. And yes, you will soon learn that the only time the PT lets you down is when you desperatly need it or it is completely inconveniant to repair (Actually I think this is a rule for any tractor - Never had one break down in the shop, it was usually fully loaded in the back 40 in the middle of a muddy field).

 

[ponytug]

And snowing...with grizzly bears nosing around.
:laughing:

But yes, I once blew a wheel motor seal on a 35 degree angle, down the hill from the road. Not exactly the place that you would choose to try and do open heart surgery to replace the wheel motor.

But back to the OP questions:
I'd be checking that fuel solenoid to make sure it is functional and not sticking on you.

X2 on Woodlandfarms comments about how small a particle you need to gum up a carburetor jet. It can be really, really tiny, which means when you do the tear down and rebuild, the area has to be really, really clean and free of dust, including cleaning the fuel lines and solenoid so that you don't wash more crud into your nice clean carburetor.

All the best,

Peter


All the best,

Peter

The thing about a carb is that all it takes is something small... Really small. I would do the teardown just for good measure. And yes, you will soon learn that the only time the PT lets you down is when you desperatly need it or it is completely inconveniant to repair (Actually I think this is a rule for any tractor - Never had one break down in the shop, it was usually fully loaded in the back 40 in the middle of a muddy field).