troubleshooting MS carburetor rebuild woes

wellssc2002 · Jul 20, 2018

My 1961 Ford 861 Powermaster began running very rough a while back, particularly when the engine was cold. I purchased a rebuild kit for the carburetor, a Marvel Schebler TSX 813. After everything was put back together, the best I could get it to do was fire up and run for 2 to 3 seconds with revving and some backfiring before shutting down, and this only after much cranking. Both the idle jet and main jet were one full turn from the bottom, plus some further adjustments to try to get it to run.

I disassembled the carburetor again and noted that the new float pin was longer than the original, resulting in the float resting at a slightly greater distance than the normal position of parallel to the carburetor body when held upside down. That would result in the bowl never quite filling, right?

I considered using the old float pin with the new float seat, but it didn?t fit as tightly into the seat, wallowing a slight bit side to side. Using the old float seat was not an option, it was all but destroyed during the rebuild.

I adjusted the float so that it rested parallel with the carburetor body, reassembled the carburetor, and remounted it. Now it does fire up smoother, but it takes a good bit of cranking. It doesn?t rev as much, now runs for around 3 to 7 seconds, but still won?t stay running. Any advice would be greatly appreciated.

Janicholson · Jul 20, 2018

Are you using the choke? If so, I think it is a supply issue not getting fuel to the needle and seat. Jim

wellssc2002 · Jul 20, 2018

I am using the choke. Full choke won't allow the engine to fire. A small amount of choke does seem to coax it to fire, but it doesn't run long enough to make any adjustments.

wellssc2002 · Jul 20, 2018

Jim, I should have added that fuel flow from the tank is fine, and the sediment bowl is full. Thanks, Scott

Traditional Farmer · Jul 20, 2018

Probably the neopreme/rubber or whatever the needle is made of these days is not letting gas by.Those all metal needles are like Gold to me.BTW is gas flowing thru the line where it hooks to the carb? Is the gas tank at least 1/2 full?

wellssc2002 · Jul 20, 2018

Gas is flowing through the line connected to the carb. The tank is not half full; not empty, but completely covering the fuel pickup.

IanC · Jul 20, 2018

When you rebuilt the carburetor did you physically clean the passages with a small drill bit (or what I use an acetylene torch tip cleaner)? Spray or soaking in cleaner will not remove rust, it has to be mechanically removed.

optiman · Jul 20, 2018

I know this may not help your current situation but i have alwayas used mmo.a good solvent.not much just to keep those small holes clear. it was made by ms carburator company just to stop gumming up

JMOR · Jul 20, 2018

(quoted from post at 19:57:54 07/20/18) Jim, I should have added that fuel flow from the tank is fine, and the sediment bowl is full. Thanks, Scott

K, so line from tank and sediment bowl is fine, but..........finish up the rest of the path. Remove carb bowl drain plug and verify that flow continues well past simply emptying the carb bowl. It should keep on flowing. Generally recommend let it flow a full pint in less than 2 minutes.

BigDanT · Jul 20, 2018

Might try removing drain plug and screwing in a nipple, attach a clear plastic hose and turn on gas. You'll be able to see where your fluid level is in your carb. This one is a little low but ran good this way.

Steve@Advance · Jul 20, 2018

Sounds like a lack of fuel in the bowl.

A simple test, remove the drain plug, install a barb fitting, push on a piece of clear vinyl tubing. Turn the open end of the tube up above the carb. Turn on the fuel valve and watch the level rise in the tube. The level in the tube will be the level in the bowl. I'm guessing the level should be about 3/4-1/2" below the top of the bowl.

Has any carb work improved the running? Possibly there is another problem. If there is fuel in the bowl, and the main jet is open, the carb should at least function, maybe not run good, but enough to make further adjustments.

The revving could indicate a major vacuum leak. Another test, remove the coil wire from the distributor and ground it. Open the throttle, hold your hand tightly against the air horn of the carb. Have an assistant crank the engine through. You should feel a strong, steady vacuum against your hand, and your hand will be wet with gas.

If good vacuum and no gas, indicates clogged main circuit or no fuel in the bowl.

If no vacuum, or weak vacuum, indicates a vacuum leak or valve problems. If no vacuum leak, run a compression test, look the valve train over for stuck valves, bent push rods, broken springs.

wellssc2002 · Jul 20, 2018

I soaked it overnight in a bath of carb cleaner and used a stiff wire to clean all the passages followed by compressed air. Thank you

wellssc2002 · Jul 20, 2018

I will check the fuel level via the drain plug & clear tube as well as check the vacuum and post the results. Thank you all very much for the help.

rlp in Co. · Jul 20, 2018

I like that little trick!

James Howell · Jul 20, 2018

Excellent photo of the "[i:654c4848f0]test[/i:654c4848f0]" on Marvel Schebler carburetors discussed in several John Deere operator's manuals.

Thanks for sharing the photo with us.

Bill in IL · Jul 20, 2018

I will be of no help here but I did have a schebler carburetor on a Waukesha engine in my old Michigan loader it was a TSX something. I never was able to make that one work. I had it apart many times scrubbed, soaked blew out passages but it would only run with the choke on. I ended frustrated junked it and bought a new carb for that machine.

So I would be very curious what you figure out in the end.

Traditional Farmer · Jul 21, 2018

Good point,I've had to actually drill out the small holes in the bottom of the carb that had stuff packed in them.

Traditional Farmer · Jul 21, 2018

If it ran the engine when it was new there is no reason it can't be rebuilt to run the machine again,lots of little details reworking a carb people often overlook or ignore.

Bob · Jul 21, 2018

"the new float pin was longer than the original, resulting in the float resting at a slightly greater distance than the normal position of parallel to the carburetor body when held upside down. "

You should have stopped right there and got the correct carb kit.

Sounds like yours may have come from "The Horse Feed Store" or similar, by way of "The Land if Almost Right".

And, what you are calling a "float pin" is called by everyone else the "inlet valve needle", or the "float valve needle".

"old", a frequent contributor to this site, swears by B/W carb kits from O'Reilly's, I've had good luck with "Hygrade" kits from Standard Motor Products. (Actually the same parent company, "SMP".)

Also, the kit appears to be available from FIAT dba CNH as part number C547CVGV.

wellssc2002 · Jul 21, 2018

There is a steady flow of gas from the carb drain. There is firm steady vacuum pressure on my hand at the carb throat at when I crank the engine on full throttle. More than a tablespoon of gas poured out the carb throat when I removed my hand.

Hopefully, the picture successfully loads with this post. The fuel level is approximately 3/4" down from the top of the bowl.

When I attempt to crank it with no choke applied, the fuel level drops very little. With full choke, it drops considerably.

With the throttle all the way open and the choke fully closed I could get it to fire and run very roughly, albeit at very low rpms.
The longest it ran was for about seven seconds. Other than that it was difficult to get it to even fire. I've not run a compression check yet.

wellssc2002 · Jul 21, 2018

wellssc2002 · Jul 21, 2018

Compression from the front of the engine to the back is 120, 135, 135, 150. This engine has had some blow-by on the cylinders all the years I've owned it.

fixerupper · Jul 21, 2018

Well here's something you can try; shoot ether in the carb and see if it starts and runs. If it runs keep shooting ether in it to keep it running for awhile. If it still dies after seven seconds you just might have a bad condenser. A weak spark can mimic a lean carb setting. Stand to the side of the carb when you are shooting the ether in case it burps. Have a fire extinguisher or a garden hose handy.

JMOR · Jul 21, 2018

float set wrong/as Bob said, needle too long resulting in gas level in carb bowl beeing a out a half inch too low.

JMOR · Jul 23, 2018

any progress?

wellssc2002 · Jul 23, 2018

I've not been able to work on it since Saturday (I'm a pastor, so Sundays are pretty busy for me). I'm hoping to work on it Tuesday evening.

I should have mentioned that when I noticed the float not sitting at the proper angle, I adjusted it so that it conforms to what I read was supposed to be the proper height (parallel with the float bowl).

As a recap, I've replaced all the parts on the carb, adjusted the float level, tested fuel flow through the carb drain, measured the fuel level on float bowl (see picture), hand tested for proper vacuum,
measured the compression, and replaced the condensor and points (last year).

The only thing I've not yet checked that was recommended here on the forum is to see if spraying starter fluid into the carb throat will make it run. I plan to check that on Tuesday evening.

Not that it really matters, but I am trying to get this tractor running in order to sell it. We sold our place in the country and moved into town because of work, so I have no need of it anymore.

I greatly appreciate everyone's help and insight. Thank you!

JMOR · Jul 23, 2018

" proper height (parallel with the float bowl)." If that is an AND, then probably OK, BUT, if you are assuming that proper height is achieved when parallel then it is likely wrong. Height is a specified dimension from the gasket surface to a specified point on the float.

wellssc2002 · Jul 23, 2018

(quoted from post at 08:47:58 07/23/18) " proper height (parallel with the float bowl)." If that is an AND, then probably OK, BUT, if you are assuming that proper height is achieved when parallel then it is likely wrong. Height is a specified dimension from the gasket surface to a specified point on the float.

I did what I considered a pretty thorough search to find specifications for a TSX-813 (a couple of hours of looking), but couldn't find anything specific to the model. In the absence that, I based the measurement parallel (with a specific dimension, but I can't recall what it was) on a video of a gentleman who does a lot of MS rebuilding. If someone knows where I can find measurements specific to a TSX-813, I would be indebted.

JMOR · Jul 23, 2018

Ask & ye shall receive.

wellssc2002 · Jul 23, 2018

JMOR, how very kind. Thank you!

Scott

Brian G. NY · Jul 23, 2018

(quoted from post at 02:29:44 07/21/18) Might try removing drain plug and screwing in a nipple, attach a clear plastic hose and turn on gas. You'll be able to see where your fluid level is in your carb. This one is a little low but ran good this way.

[color=blue:96152c5094][b:96152c5094]Wow.....never even thought of that.....good idea to see where the gas is "in the real world"!
[/b:96152c5094][b:96152c5094][/b:96152c5094][/color:96152c5094]

wellssc2002 · Jul 23, 2018

(quoted from post at 10:03:18 07/23/18) Ask & ye shall receive.

Took the carb off and adjusted the float to 1/4" (required about a 1/16" adjustment). While apart I double checked every orifice visible without removing any jets, seat, etc. to ensure they were clean.

Reassembled and reinstalled. Couldn't get it to fire at all, not even with starting fluid. Checked for spark, none observed. Cleaned points. It fired some, but no better than it had been the day before.

A friend who is a good mechanic is coming to look at it tomorrow. I'll update on any progress. Blessings!

JMOR · Jul 23, 2018

(quoted from post at 21:12:56 07/23/18)

(quoted from post at 10:03:18 07/23/18) Ask & ye shall receive.

Click to expand...

Took the carb off and adjusted the float to 1/4" (required about a 1/16" adjustment). While apart I double checked every orifice visible without removing any jets, seat, etc. to ensure they were clean.

Reassembled and reinstalled. Couldn't get it to fire at all, not even with starting fluid. Checked for spark, none observed. Cleaned points. It fired some, but no better than it had been the day before.

A friend who is a good mechanic is coming to look at it tomorrow. I'll update on any progress. Blessings!

est wishes, but it sounds like more than one problem.

wellssc2002 · Jul 24, 2018

So I replaced the plugs and reset the gap on the points. It ran at a chug idle a little longer, maybe 10 seconds at most. Swapped out the coil with a coil I had laying around. It ran at a chug idle a little longer, maybe 20 seconds, and without having to constantly adjust the choke. But I can't open the throttle without it shutting down. It's a little closer, but still nowhere near running even remotely like it should.

Here's a question: are 12-volt coils all the same or do I have to get one specifically for this application?

JMOR · Jul 25, 2018

(quoted from post at 21:16:19 07/24/18) So I replaced the plugs and reset the gap on the points. It ran at a chug idle a little longer, maybe 10 seconds at most. Swapped out the coil with a coil I had laying around. It ran at a chug idle a little longer, maybe 20 seconds, and without having to constantly adjust the choke. But I can't open the throttle without it shutting down. It's a little closer, but still nowhere near running even remotely like it should.

Here's a question: are 12-volt coils all the same or do I have to get one specifically for this application?

ot all same. Some have high enough primary resistance to limit current to about 4 to 5 amperes, but others with lower primary resistance need a series ballast resistor to limit the current. If current is too high, it will still have good spark, but points will have shorter life.

wellssc2002 · Jul 25, 2018

I failed to mention that I was unable to get it to run even using ether sprayed into the carb throat. Not ruling out that it may be both a fuel and ignition problem, would the inability to run with ether point toward an ignition problem?

Wondering if it may have jumped time, I adjusted the timing to see if the engine might run at least a little smoother. There was some effect, but not much. Can I rule out jumped time or do I need to measure TDC on cylinder #1 and check the location of the rotor?

At this point, I'm considering replacing everything from the coil to the rotor that has not been already replaced (about $42) out of frustration.

JMOR · Jul 25, 2018

(quoted from post at 13:14:45 07/25/18) I failed to mention that I was unable to get it to run even using ether sprayed into the carb throat. Not ruling out that it may be both a fuel and ignition problem, would the inability to run with ether point toward an ignition problem?

Wondering if it may have jumped time, I adjusted the timing to see if the engine might run at least a little smoother. There was some effect, but not much. Can I rule out jumped time or do I need to measure TDC on cylinder #1 and check the location of the rotor?

At this point, I'm considering replacing everything from the coil to the rotor that has not been already replaced (about $42) out of frustration.

wouldn't worry about the timing. If gears jump a tooth (broken?) then it will be so far off that it will fire out exhaust or carb (drastic enough that you will know it). If you star messing with timing, you will just introduce another variable. As long as you have been at this, the plugs are probably fouled by now. If you have spark & it won't fire on ether, then swap plugs....even an old set.

troubleshooting MS carburetor rebuild woes

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