Go to the Sears Direct web site and download a free copy of the owner's manual.
It has a schematic in it. I don't know of what value the schematic will be to you as the schematic does not feature a fuel solenoid in it.
Most likely the reason it will not run except with full choke is because the carburetor main jet is clogged, and can't flow enough fuel to meet the needs of the engine when you open the choke to let more air into the engine. Applying choke is essentially cutting off air until it matches the trickle of fuel that is available through the carb in its current state.

For a Briggs Intek in a Craftsman that is similar to what you have, get the owner's manual for tractor model 917.272140.

Probably be a good idea to post the model and type numbers off of the engine too.
Once you have those numbers recorded, you can go to the Briggs web site and down load a parts list manual (IPL).

Here is a link that might be useful: source the manual

The fuel solenoid needs 12V to function.

Looking at your schematic, you could tie it in to the L terminal of the key switch. The wire with the "lift kit" attached to it.
That would turn it off when the key was off.

This post was edited by bill_kapaun on Sat, Aug 3, 13 at 22:10

Mownie and Bill: Thanks for the prompt responses! I had forgotten (or never knew) about getting the download for the owners manuals through the sears parts pages, very helpful and I think I can do some tracking down with the schematic. I know the PO had been working on electrical problems but I didn't want to ask too many questions since he was giving me the mower.

I had seen some references that seemed to say that the carb solenoid controlled the main jet on the carb as opposed to shutting off all the gas. If this is true, it may explain the run on choke only symptom, if not I will disassemble and clean the carb.

I see about hooking the solenoid to the L terminal on the ignition switch. BTW, what is a "lift kit"?

Thanks again, Ray

Your tractor is a GARDEN TRACTOR, not simply a lawn mower.
The item you see in the schematic likely implies that there is an unused connector plug in place (probably behind the dash board) where the optional electric sleeve hitch would connect to the electrical system if an owner wanted to add that upgrade to the machine.
A sleeve hitch is basically a self contained raising and lowering device used with plows and tillers on the rear, or it can be part of a dozer blade or snow plow package mounted to the front.
It gives an owner the convenience of a "hydraulic system" lift, without an actual hydraulic system.

This post was edited by mownie on Mon, Aug 5, 13 at 0:48

The carb solenoid has a plunger that blocks the Main Jet when the solenoid is OFF.
When ON, the plunger is retracted.

Many people still think that it's a fuel shut off to the carb bowl.
IF they just looked at the carb, they'd see it has nothing to do with the float, needle & seat.

As a side note-
The L terminal isn't "hot" in the start position, thus the solenoid won't be ON during start. It will be on as soon as you release the key to RUN.
That may or may not be a problem.

This post was edited by bill_kapaun on Sun, Aug 4, 13 at 20:33

Bill: I think the L terminal would still work. If I am looking at this correctly, it will start now without the carb solenoid being made so that part should be the same.
Mownie: Makes perfect sense. I was wondering why you would need an assisted lift with a deck this size, but an electric sleeve hitch would.

I ordered an ignition switch today, as well as an operator present relay (less than $2 and I had to pay flat rate shipping anyway). I'll post again after I get the switch installed.

Without the seat switch, the OPR is going to prevent running while the deck is engaged.

***"Without the seat switch, the OPR is going to prevent running while the deck is engaged."***
True, but ONLY if the seat switch wiring connector is still in place in its OEM condition as part of the wiring.
If someone has cut the wires to the seat switch connector, thereby defeating the switch CONNECTOR SHORTING function, the seat switch and OPS relay WILL NOT act to kill the engine.
Since louky stated in his opening post that the seat switch has been removed, I have to infer that the switch connector has also been removed, or that the shorting contacts of the CONNECTOR have been tampered with while in the custody of the previous owner.
Louky does not say whether HE removed the switch (as part of a diagnosis scheme) or if the switch was missing when he got it.
Louky, do you want to clear the air on the seat switch issue?
:^)

Yes, I was unclear on this point. I was just describing the situation as I found it from the PO. The seat switch is in place and tests OK. The connector and wires are "disappeared" and I haven't taken the rear fenders off yet to see if the connector has been pulled under the body or if it has indeed been cut off. The schematic will really be helpful for me to find this out. If I understand what you all are saying, if the lines have been cut and taped up separately, the system is is "fooled" and this would allow start and run (if everything else is OK). If the connector has merely been unplugged, then it would prevent running while the deck was running (but I think you could still start it with the PTO disengaged)?? I've found a few other "head scratchers" since I originally posted. The 20hp intek has about 1 inch spacers between the engine and the frame. One of the spacers was missing but I didn't think much of it. Looking under the mower today and realized that someone has removed the v belt idler pulley next to the PTO. This pulley (I believe) is bolted through the frame, another spacer, and is the same bolt where the spacer is missing. Since the drive train works right now, I'm pretty sure this means that someone has installed a shorter belt to make it work. Who knows what the chronology is on this! I have another tractor to steal the pulley and proper belt from to see if this is correct. (That's after the ignition switch LOL)

Frankentractor! It's alive...................it's a li hi hive!
Good luck.............sometimes these monsters will bite the hand that feeds them.

Although I haven't received my switch yet I did a little more troubleshooting and have some good news. I finally got the ignition switch terminals and plug clean enough to work some and found that indeed the carb solenoid opens with the switch in run position and the engine sounds good and will run without the choke on. I was able verify that the clutch/brake switch, the pto switch and the OPR are working. Took the deck off to check spindles and sharpen blades, and checked that the PTO clutch is working. I installed the idler pulley next to the PTO that had been removed and installed proper length drive belt. I think all I have yet to do electically is change the switch when it gets here and to get some wires run to the seat switch since I don't feel comfortable with this particular safety bypassed. I will probably take the rear fenders off to install a new fuel line and filter, adjust emergency brake and do a general inspection of this area, and rerun the wires to the seat switch at that time. May also service with rear end oil then. Thanks for all the help so far.

Glad to hear there's progress!

With Bill's help I've discovered that the PO had installed a normally open seat switch in the mower rather than the correct one. I will order a new switch and report back when I get it installed.

On to the charging circuit: This engine is not original to the mower. Briggs model 407777 Type 0120E1: Battery reading 12.8 volts at high RPM. I unplugged the connector coming from the stator. I am getting 25.8VAC across these two pins. I can't get a reading on either pin to ground however. Not sure how to read the red wire coming out of the regulator. Thanks for any input! I pulled this picture from a different thread but it is what mine looks like.

Are you getting your 25.8 VAC at HIGH engine speed?
Specification is 28 VAC minimum at high speed.
IF your test was at lower speed, re-test at high speed.

IF the battery is very low/bad, it may be "dragging down" the output.

A fully charged battery is 12.6V. At 12.2V, the battery is considered too low for proper testing.

BTW- Where's the RED wire going?

This post was edited by bill_kapaun on Wed, Aug 14, 13 at 13:04

Your test indicates that this is the 10 amp regulated charging system. ***25.8 VAC*** From the Briggs manual: "With engine running at 3,600 RPM (stator) output should be NO LESS than 20 volts for 10 Amp system".
There should NOT be any reading when going from either stator output wire to ground when checking this "2 wire output" stator.
The Red lead on the regulator is the regulator OUTPUT lead. It delivers any charging output to the battery positive circuit.
If you can read BATTERY VOLTAGE by checking the chassis side of that red wire circuit (disconnected from regulator wire) going from red wire to ground, that circuit is good (meaning that it is in fact connected to the battery). If you cannot read battery voltage at the red wire on chassis side as I described above, there will be no charging current delivered to the battery.
So, if you cannot read battery voltage on chassis side of the red wire, you need to trace the red wire out and see why it is not connected to the battery positive circuit.
If the red wire shows battery voltage in the above test, and your reading never climbs higher than12.8 volts across the battery at high RPM...........even after running for as long as 30 minutes............ the regulator is defective.
And it can take a few minutes for the voltage of the battery to climb out to a maximum point as the battery slowly absorbs the charge.
It WILL NOT instantaneously jump up to 13.6 (or higher) when the engine is revved unless the battery is already in a full state of charge.
Or you can visualize it like this:
If you are filling a glass with water and all you have is a small trickle to fill it, the glass will take a while to fill to the point of overflowing (full glass = full battery charge).
But, if the glass is already filled to the top, it will overflow as soon as you add more water.
The battery charging process works in similar fashion.

This post was edited by mownie on Wed, Aug 14, 13 at 13:25

The red wire goes into a shrink wrapped assembly which I cut open. It is hooked to two diodes. The diodes go to a double plug with an orange and red wire. The orange wire then goes to the headlight switch and the red wire goes to the (I think) L terminal on the ignition switch.

OK-
You have to eliminate the diodes.
The ORIGINAL system used 2 diodes from ONE AC lead from the stator-
The diodes were opposite polarity-
One (red) gave + DC for charging and the other (orange) gave - DC for lights.
Look at the original schematic.

Just remove the diodes and splice both those wires to the RED wire coming off the VR.

Diodes have a "few" 1/10's of a Volt voltage drop. That may be the difference from what you should be getting and what you are getting.

Were your tests at high engine speed?

This post was edited by bill_kapaun on Wed, Aug 14, 13 at 14:53

Engine speed was as high as it would go. I've tried to attach the photo of the diode assembly. I did the test to see if I can read the battery voltage back through the red wire. There is no reading with the switch in the ON position. If I test the red wire before it comes to the diode I get a reading however no reading on the opposite side of the diode.

Are you saying to eliminate the diodes just for testing, or that they are not needed in this system. I did the diode test on my voltmeter, both acted the same both read 1 in one direction and around 510 in the other direction.

A diode simply acts like a check valve.
Electricity can flow in one direction, but not the other.

In the original system, one diode allowed the positive part of the AC sine wave to pass, giving you pulsating + DC for charging.
The other diode (reverse orientation) allowed the negative part of the AC sine wave to pass, giving you a negative pulsating DC.
Since the pulses happen so fast, you really don't see the lights flickering etc.

The Voltage Regulator eliminates the diodes and gives you straight DC out. (look up "bridge rectifier")
It also has electronics in it to regulate the voltage.

Therefore, you no longer need the diodes.

Tried eliminating both diodes and ran wire straight from the VR to the red wire coming out of the L terminal of the ignition switch. I let it run 10 minutes at full throttle. At the end of this time period I was reading 13.5V at the battery while running.

Sounds good.
You can also hook up the Orange wire (same connection) to give you lights.

BTW-
When testing diodes, you may sometimes have to try different OHM ranges on your meter.
Some meters have such high impedance, that the don't provide enough current for the diode to "conduct". Thus they will show open on both orientations of the test leads.

This post was edited by bill_kapaun on Wed, Aug 14, 13 at 17:23

Bill: I was using a setting on the meter that has the symbol for a diode on it.

To further my understanding, did this get fixed because there was a difference in the charging circuit on the replacement engine and the original? I'm trying to figure out why the diodes were even in there.

And could you give me some idea what would be a typical reading after I get the PTO running? I don't HAVE to have the lights though they'd be nice. I just want to make sure I can mow without discharging the battery. If I get a reading of 13.0V with the PTO engaged will that be enough?

Bill: I missed your post about the diodes, sorry about asking the same question twice but I think I get it now! What would be the relative draw headlights vs. PTO clutch?

The PTO will be somewhere around 3-4 amps.
Headlights are (I think) about 2.1 amps ea.