Marvel Schebler Tsx flooding?

[Adam from WI]

I have a tsx carb that runs a little rich at idle. It would run really smooth a few seconds after shutting the fuel off. I put a kit and a new float in it figuring it was the float or the needle. But after the new parts it's the same thing. I can hear the float move, and it's set to 1/4" to the gasket. I'm thinking of just tweaking the float down another 1/16" or so unless there's something else I should look for.

 

[CaseandMoline]

Did you change the seat as well?

 

[Adam from WI]

Yes

 

[molinegb]

Most new carb kits best left in box. Needle and seat poor quality and needle sticks Our new gas as well as any sediment will cause flooding just sitting.

 

[J.Wondergem]

Years ago I had a new float valve and seat that leaked on something. Took it back where I bought it and in the back room they repaired vehicles. The guy back there took float out and taped the valve in the set with a small hammer. Said it needs that to make a good seat. That was before rubber tips.

 

[scootergmc]

Try 1/4" from carb body surface, not gasket.

And did you get a good carb kit? Not an cheapo Amazon? I've had much better luck from places like Carb Dr., etc.

 

[Jim.ME]

Try 1/4" from carb body surface, not gasket.

And did you get a good carb kit? Not an cheapo Amazon? I've had much better luck from places like Carb Dr., etc.

If he wants the float lower, he needs to set it 5/16" from the body gasket surface. 1/4' from the body gasket surface actually will raise the float compared to having the gasket in place when measuring.

The float needs to be parallel to the body surface. I like to use a drill bit to check the length of the float(s).

 

[scootergmc]

If he wants the float lower, he needs to set it 5/16" from the body gasket surface. 1/4' from the body gasket surface actually will raise the float compared to having the gasket in place when measuring.

The float needs to be parallel to the body surface. I like to use a drill bit to check the length of the float(s).

Yes I'm aware and understand the issue, but this is my rule of thumb when it comes to setting the level on our MS carbs (on our Olivers for sure). Go from there. If the float height is set like this (and the tang hasn't been abused and the pontoons don't have pinholes), and continues to flood, then the problem is almost always elsewhere. As I'm sure you know, a clear tube and a fitting on the bowl is the quickest indicator of fuel level.

 

[Adam from WI]

The float needs to be parallel to the body surface. I like to use a drill bit to check the length of the float(s).

This was a great idea. I was 2 screws back together when I saw this post, so I took it back apart and checked with an allen key. I have it at 5/16 now and it idles noticing noticeably better, but it still improves after I shut fuel off.

Also, both times I had the carb off, the engine backfired out the exhaust when starting. Not sure what the deal is there

 

[scootergmc]

This was a great idea. I was 2 screws back together when I saw this post, so I took it back apart and checked with an allen key. I have it at 5/16 now and it idles noticing noticeably better, but it still improves after I shut fuel off.

Also, both times I had the carb off, the engine backfired out the exhaust when starting. Not sure what the deal is there

I'm trying the understanding a little bit. You're saying it idles better as the fuel shuts off and runs out?

And it backfires when you have the carb off? Are you using starting fluid?

 

[Adam from WI]

It backfired both times I had the carburetor removed. Just the first start after reinstall.

Yes, it idles better after shutting fuel off which is why I lowered the float some. It's much better, but it still improves after fuel is turned off and the bowl level gets drawn down. I'm wondering just how much I can lower it...

 

[molinegb]

If backfiring and running on is a timing or ignition issue not carb.

 

[Adam from WI]

Today I checked and there was gas in the air intake hose (I left fuel turned on). I pulled the bowl down and checked the needle and seat again with the fuel on. No drips seen there. I've tried a float setting that was a 32nd shy of 3/8 and it'll still eventually start puffing a little black at idle. It's done this now with the original float at 1/4, a new float at 1/4" and the new float set progressively lower. I guess I'll try putting some sealant on the seat threads and cleaning those parts again. The only other thing I noticed is that the rectangular hole in the gasket that connects the idle air passage to the upper half isn't a perfect line up. If I had to guess it looks like it's blocking around 15-20% of that pathway.

 

[Alan K]

Today I checked and there was gas in the air intake hose (I left fuel turned on). I pulled the bowl down and checked the needle and seat again with the fuel on. No drips seen there. I've tried a float setting that was a 32nd shy of 3/8 and it'll still eventually start puffing a little black at idle. It's done this now with the original float at 1/4, a new float at 1/4" and the new float set progressively lower. I guess I'll try putting some sealant on the seat threads and cleaning those parts again. The only other thing I noticed is that the rectangular hole in the gasket that connects the idle air passage to the upper half isn't a perfect line up. If I had to guess it looks like it's blocking around 15-20% of that pathway.

I would double check the float, even if it is new. Take it out and shake it and also see if it floats on its own. If you shake it and hear liquid it leaks. Had that on an M5 and my cousins ZA.

 

[scootergmc]

Today I checked and there was gas in the air intake hose (I left fuel turned on). I pulled the bowl down and checked the needle and seat again with the fuel on. No drips seen there. I've tried a float setting that was a 32nd shy of 3/8 and it'll still eventually start puffing a little black at idle. It's done this now with the original float at 1/4, a new float at 1/4" and the new float set progressively lower. I guess I'll try putting some sealant on the seat threads and cleaning those parts again. The only other thing I noticed is that the rectangular hole in the gasket that connects the idle air passage to the upper half isn't a perfect line up. If I had to guess it looks like it's blocking around 15-20% of that pathway.

Don't use sealant anywhere in the carb. Just don't. Did you get yourself a quality kit or a cheapo Amazon or eBay?

 

[Adam from WI]

Well folks on today's episode we learn don't ever assume something is right because it was that way when you took it apart. And no, scooter; this wasn't an Amazon or ebay kit.

I had a suspicion lately; I wonder if my load needle is correct. And not just correct, but the seal, spring, etc that goes at the top. Instructions for this are kinda grainy and understanding what small parts go where is tricky. So, we just make it as close to original as possible. Right? Well no, not really. See, on disassembly the load screw had a spring under the head and a thick black seal under that. The head sat about 1/4" above the body of the carb. Putting back together this way made for a real tight turning affair once i got to where the original was setting. So, I figured that was seated.

Well, today I decided to take all that out and see how deep that load screw has to go. Turns out, it had another 1/4" to go before firmly seating. D'oh...

So I get rid of the spring and keep the tight, thick, black seal and get the load screw set a proper one turn off closed. I fired up the engine to hear that sweet smooth idle I was getting before when running the tractor with the fuel shut off.

Awesome, right?

Well, hold on... I do a couple quick snap tests to find an engine that's hesitant, and backfiring. I got the float set way low now, remember? Pull the carburetor off for the ninth time and put it back to original spec.

Fire up: idle joy!

Quick snap: a bit hesitant, but recovers well. I think a road test and a 1/4 turn one way or the other should get it happy. Setting the load first is definitely the way to go though. Any little change there required a follow up tweak to the idle screw. Some resources don't touch on this.

I think I'll get it dialed in from here. It sounds great, and no more puffs of black.

 

[Ill John]

Awesome!!!