1520 Gasser

[Robin Hood]

Two questions:
The first is about the carburetor design. I am rather curious for an explanation as to why John Deere outfitted the carb with an electric fuel solenoid shut off valve. I don't profess to be a mechanic, but the idea of a solenoid valve AND a mechanical fuel pump seems to be a little bit redundant. Especially when you consider all of the other tractors out there with neither.
The tractor has been mostly sitting for the past few years, but it runs very good. The problem I have is the solenoid valve has a very small leak when the engine is shut off. Its bad enough that I have to shut of the fuel supply at the tank. Is this a leak caused by the float not closing the needle valve off, is the solenoid valve housing cracked, or is there possibly an o-ring inside that I could replace. I am told the valve is more than $200 to replace.
Second question is the weight of the wheel weights. The tractor has power shift rims (14.9-28) with 2 pairs of weights that are attached with four bolts each. I am embarrassed to say that I can barely lift one. Any idea what they might weigh?

 

[wore out]

Two questions:
The first is about the carburetor design. I am rather curious for an explanation as to why John Deere outfitted the carb with an electric fuel solenoid shut off valve. I don't profess to be a mechanic, but the idea of a solenoid valve AND a mechanical fuel pump seems to be a little bit redundant. Especially when you consider all of the other tractors out there with neither.
The tractor has been mostly sitting for the past few years, but it runs very good. The problem I have is the solenoid valve has a very small leak when the engine is shut off. Its bad enough that I have to shut of the fuel supply at the tank. Is this a leak caused by the float not closing the needle valve off, is the solenoid valve housing cracked, or is there possibly an o-ring inside that I could replace. I am told the valve is more than $200 to replace.
Second question is the weight of the wheel weights. The tractor has power shift rims (14.9-28) with 2 pairs of weights that are attached with four bolts each. I am embarrassed to say that I can barely lift one. Any idea what they might weigh?

I think the idea behind the fuel solenoid is to close off the main jet when the ignition is switched "off" possibly preventing a loud "backfire" when unburned fuel hits the muffler when the engine is shut down "HOT".

The carb solenoid (unlike an electric solenoid valve in a fuel line) doesn't prevent gasoline from entering the carburetor and overflowing it if there is a float or needle and seat problem.

As to the solenoid leaking, I doubt there's a "fix".

If you are willing to put up with an occasional muffler backfire you can simply replace it with a manually-adjusted load needle for a lot less $$$.

Places like Roberts Carburetor or McDonald Carb and Ignition should be able to set you up with the parts to do that.

I can't help you with the weight of your weights.

 

[ET]

Actually the function of the solenoid is to prevent the engine from diesiling when its shut off by cutting off the gas flow to the hot cylinders.

 

[Fixingfarmer]

All 3 of you are right. I have seen and I believe the op has an example of there's enough fuel in the tank it still will leak. Honestly the one thing I haven't played with is the bottom fuel line on these tractors but it should be out the bottom the only thing in the top is a diesel return if it was a diesel.
It would be hard to get it hot enough to diesel but that's what the engineers put it there for. Ive never seen it happen thats where it shuts down and keeps going if its a gas. The choke lever is also there in that case you would think that would be enough.
You might want to check what number carb you have if there's a tag on it. The parts breakdown shows a replacement carb the original must have been a marvel schebler if you have the replacement carb the screw eliminating the solenoid is RE39190 but I don't know if I trust their parts diagrams so much on this particular model it sure looks like the zenith carb I rebuilt last week. Find the tag or the casting number if you can because there are 4 possible options and I bet you have one of the bottom two.

 

[Robin Hood]

Two questions:
The first is about the carburetor design. I am rather curious for an explanation as to why John Deere outfitted the carb with an electric fuel solenoid shut off valve. I don't profess to be a mechanic, but the idea of a solenoid valve AND a mechanical fuel pump seems to be a little bit redundant. Especially when you consider all of the other tractors out there with neither.
The tractor has been mostly sitting for the past few years, but it runs very good. The problem I have is the solenoid valve has a very small leak when the engine is shut off. Its bad enough that I have to shut of the fuel supply at the tank. Is this a leak caused by the float not closing the needle valve off, is the solenoid valve housing cracked, or is there possibly an o-ring inside that I could replace. I am told the valve is more than $200 to replace.
Second question is the weight of the wheel weights. The tractor has power shift rims (14.9-28) with 2 pairs of weights that are attached with four bolts each. I am embarrassed to say that I can barely lift one. Any idea what they might weigh?

Thanks guys. You have educated me. As far as dieseling goes, I guess I could just let the clutch out while its still in gear.

 

[Jim.ME]

Thanks guys. You have educated me. As far as dieseling goes, I guess I could just let the clutch out while its still in gear.

wore out is correct, the needle closes the main jet off when the ignition switch is shut off to prevent gas getting to the intake through the main jet, it does not shut off gas coming into the carb. The gas engines can diesel or kick back at times when shutdown hot. I have replaced a couple solenoids (one on a 1520) with an adjustable manual needle from McDonald. You just need the carb number when you talk to them, this site, or Robert's to get the right needle set up for the carb. The ones have replaced only require removing the solenoid and installing the new needle and holder, then adjusting, no need to take the carb off or tear it down. Giving the engine a couple minutes to idle down as slow as it will idle, and stabilize, before you shut it off will generally take care of the dieseling, kickback, and backfiring. As you noted you can let the clutch out, in gear, if it does start to diesel or kick back.

 

[Fixingfarmer]

Oh I forgot about the weights. 110 or so possibly a bit lighter