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Tecumseh HS50 New Carb Troubles


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  #1  
Old 01-25-2018, 08:13:41 PM
J Dayman J Dayman is offline
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Default Tecumseh HS50 New Carb Troubles

Got a brand new carb for a Tecumseh HS50 I am working on. Its part number is 631953, a service carb, reportedly made by Certified Products in the USA.

Tried everything I know, I can not get the float needle to stop sticking up into the seat. If I use lung pressure by mouth through a piece of fuel line to blow it down away from the seat it will then feed 1 bowl of gas, and then engine runs about 5 minutes only until that bowl is gone. It will not pass any more fuel after that bowl until the float needle gets blown downward with mouth air pressure again. I've checked the fuel tank, valve, and fuel line, they all pass lots of fuel without any trouble for 20 min or more. I'm sure the float needle is sticking in the seat in this brand new carb!

My question to the forum is - has anyone seen this with these carbs, and what was done to fix it?

I don't want to wait another week for a replacement since after it comes, if made in the same lot from same materials on same tooling chances are good it will have the same problem.

I've worked on small engines for many years and never had this much trouble with a brand new carb. Usually they work great right out of the box, at least the ones I've bought did.

Thanks for any help and advice you may have.
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Old 01-25-2018, 09:32:33 PM
Greg Mosley Greg Mosley is offline
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Default Re: Tecumseh HS50 new carb troubles

Greetings j dayman, Possible fix for your scenario. I'm assuming by code its a 5 hp. horizontal shaft engine for snow blower duty. (1) The fuel bowl installs in only one position. If not on right that will crate issues. (2) Slide the float pin out, and look at the seat. If the construction is the same as the original there will be a viton seat pressed in. Many people not knowing will blow out that seat and re-assemble. What happens, the seat sticks. If MIA take an oring pick and remove it from the old carburetor and install in the new. (Or purchase a needle and seat kit) This square cut oring has a circular mark on one side. That side installs towards the carburetor body. If you do not heed this it will flood. (3) There is also a fine wire link that attaches the float and needle together. If that's missing replace. (4) Make sure float level is correct. Enuf Said
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Old 01-25-2018, 10:27:08 PM
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Default Re: Tecumseh HS50 new carb troubles

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Originally Posted by Greg Mosley View Post
Many people not knowing will blow out that seat and re-assemble. What happens, the seat sticks.
If that seat is blown out there wont be anything in there for the inlet needle to stick to and the carb will simply flood over until the tank is empty.

To the O.P:
I would warranty the carb. They arent cheap from Tecumseh anymore even though they're made in China now. If you dont want to warranty it buy an inlet needle and seat kit and replace them. Dont try using an old seat they usually get ruined trying to extract them or they're swelled up from ethanol.
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Old 01-25-2018, 11:11:46 PM
Greg Mosley Greg Mosley is offline
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Default Re: Tecumseh HS50 new carb troubles

Greetings Motomowers. Brief comment. j dayman probably needs his sno-blower as of yesterday. If its anything there like it is in the states its probably Clear and Still. What I mean by that for those who don't know..., Clear up to your ass and still snowing. Beats a shovel anyday. Good Luck, j dayman
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Old 01-25-2018, 11:25:47 PM
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Default Re: Tecumseh HS50 new carb troubles

Ebay for one of those $15 chin replacements from a usa supplier. I've bought about five of them in the last few years and they work great.
Ya gotta remember that Tesuckem engines weren't that good when new.

* Check that the rubber seat is in the correct way on the carb you have. It's supposed to be a big deal but in 40 years of working on them I never had a problem with it in either way.
Does it have the little pull the needle down wire thingie that attaches to the needle and the float?
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Old 01-26-2018, 12:19:34 AM
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Default Re: Tecumseh HS50 new carb troubles

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Originally Posted by Greg Mosley View Post
Greetings Motomowers. Brief comment. j dayman probably needs his sno-blower as of yesterday. If its anything there like it is in the states its probably Clear and Still. What I mean by that for those who don't know..., Clear up to your ass and still snowing. Beats a shovel anyday. Good Luck, j dayman
So it makes sense to go through all that trouble to install used parts in a new carb rather than go down to a shop and buy a common kit and do it right? Half the time when you remove those parts from the carb they swell up and wont go back on. Most time the bowl o ring gets tossed because I wont mess with trying to wrestle with putting the bowl back on because the rubber swelled up in the few minutes it was off the carb. I have the proper Tecumseh tool #670377 to remove and install the seats and it still ruins them because some are in so tight they get cut by the tool trying to pull them out.
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Old 01-26-2018, 10:39:11 AM
J Dayman J Dayman is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Thanks for all the replies so far. To address some points raised -

-the old carb was not rebuildable because some of the zinc a lot of metal is crumbling apart.

-the new carb does have a rubber seat in place and it was not "blown out". I only "blew out" the needle off the seat with mouth/lung air pressure (like enough pressure to blow out a birthday candle - not high pressure compressed air.)

-not an option to send the carb back on warranty since they can only replace it with the same unit, also probably defective.

-I am told there is no available needle and seat kit for this carb in Canada. Parts availability and pricing is FAR different in Canada than the US. I paid more than ten times the ebay price for this carb to buy it here because after trying several stores on ebay for it none would ship it to Canada. I have a feeling some Canadian warehousing company has a monopoly in sales of these parts in Canada.

I'm going to do some experiments tomorrow using the old needle from old carb in the new carb's seat, and maybe if that doesn't work I'll try and swap the rubber seat too, although I too have had trouble with that in the past, not wanting to go back in.

Greg you are right I do need to get this thing working again soon. It is not clear still conditions as you mention right now but it looks like next week it might be, in spades!

Also this blower has been used every year since 1978 when it was bought by the family that still owns it, some neighbours of mine. (Based on this and many other Tecumseh's of similar age that I regularly run and service I don't think they built bad stuff at all as one responder said they did.) There is an emotional attachment to the damned thing and the older person who operates it now is upset about the difficulty with new very expensive carb part, and feels bad about how much time I'm having to spend messing around with it. I just want to get it back to them running like new, which it should with a new carb.

Thanks for any help or advice to get the needle to stop sticking shut. The problem is opposite to flooding - it won't feed fuel through the needle after it fills the bowl once.

Second request - does anyone on the Stak have a used but serviceable carb from a blown up HS50 they'd like to sell? I'd be interested if so - please send a private message if you do, with a price and shipping charges to Waterloo Ontario Canada. Thanks!
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Old 01-26-2018, 03:14:10 PM
Andrew Mackey Andrew Mackey is offline
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Question Re: Tecumseh HS50 New Carb Troubles

It has been asked before, on other posts - is the float/needle spring installed? This spring allows the weight of the float to dislodge the needle from its seat. If the spring is missing, the needle won't fall from the seat when the float drops . Ditto on the bowl installation. The bowl MUST be oriented so the deep side is under the float section that drops the lowest when low on fuel. If the bowl is not oriented correctly, the float cannot drop far enough to unseat the needle. The shallow section of the bowl must be centered on the float mount pin. Float level set correctly? When placed upside down, the seam in the float body should be parallel to the bowl mount casting on the carb. When you turn the carb body right side up, you might hear a distinct click as the bowl and spring unseat the fuel needle.

If all else fails, perhaps someone here in the US of A can get a rebuild kit here, and send it to you thru the mail.
Andrew
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Old 01-26-2018, 03:25:06 PM
gdstew gdstew is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Needle & seat kit 631021B. I can't believe somebody in Canada doesn't have probably the highest selling part that Tecumseh ever had!
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Old 01-26-2018, 03:44:33 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Me neither! Very odd if you can't find it locally! If you still can't get one, send me a PM
Andrew Mackey
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Old 01-26-2018, 03:52:45 PM
J Dayman J Dayman is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Andrew- sorry, yes the needle retainer spring is in place, for sure, and also the bowl is in the correct orientation relative to the float pivot pin as you mention. The float is free to move and the needle can be seen to move with the float when moved with a finger with bowl off. The float when up is parallel with the bowl ring. Like I said, I've worked on LOTS of Tecumseh and many other types of engine over the years, I don't see anything visibly bad or missing, and this is the most trouble I ever had with a new carb. The more usual problem I've seen with carbs is flooding - this carb's problem is opposite to that. As I said I do know there is plenty of sustained fuel flow right at the end of the fuel line, and I know the fuel elbow is clear as it will fill the bowl once, perfectly. Then the needle won't drop again and allow it to fill again.

gdstew- thanks for the part number on the needle and seat kit. sorry, "unavailable" is what I was told by two dealers nearby. It's quite clear from attitude and body language they don't really want to waste time on people repairing ancient machines.

akuna - the first thing I did when I noticed the issue with this carb was called the place I bought it. They did offer to do RMA on it but offered no suggestions of things to try and they said the replacement carb would come off the shelf at the Toronto warehouse right next to the one they sent me was, so if mine's bad they likely all will be. They said the extent of their support would be a replacement carb, to be shipped after they received mine, when they could get to it. I believe if there is a defect in the needle or seat on my carb likely the whole production run will have it, so waiting two weeks for another possibly bad one does not make much sense.

Thanks to all, Jeff (still stumped but got a couple of things to try tomorrow as mentioned.)
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Old 01-26-2018, 05:19:49 PM
J Dayman J Dayman is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Hi Akuna,

Fuel line has been replaced already (proper SAE fuel hose) and will feed fuel 20 min or more, lots of flow, with fuel valve open. there is no kink or collapse in the fuel line. I am sure the needle is sticking up. (don't know why it would, though.)

Good news! I just found a 631021B needle and seat kit local to me. Got that now for tomorrow's fixes / tests.

Thanks to all. Will advise how it goes tomorrow. Jeff
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Old 01-27-2018, 05:00:07 PM
J Dayman J Dayman is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Spent some time today with the HS50 on my neighbour's blower and fixed the float sticking up problem. It was interesting how that went - see below.

-put the new needle and seat kit in, keeping the new carb's plastic float and its' new pivot pin. Same problem - needle sticking up.

-took it apart, put the old carb's brass float in, left new needle and seat kit in, used new carb's pivot pin. Needle no longer sticks up, float and needle work fine. Set the float parallel to carb face with needle up. Feeds and stops fuel just like it should. Hoo-Ra at this point.

(why the plastic float would cause this issue I have NO idea, it shouldn't, but it seems to)

Now for run tests. Main needle set 1 1/2 turns. Idle needle 1 turn (initial settings). Choke on. Engine start. Choke off, engine races high. Engine races low. Engine runs perfect mid-speed for quite a while. All this time, speed control set to 3/4 full, not touched. All of a sudden, engine races high. then back to mid-speed. Then speed drops and engine stumbles. High speed again. Shut it off, then restart while watching main jet nozzle in carb with trouble light. Engine starts, nice jet of fuel coming out the nozzle, mid speed run is good. All of a sudden without touching controls there is a HUGE surge of fuel out the nozzle and engine races. Then back to mid speed, nice jet of fuel. Then slows and stumbles as the jet from the nozzle decreases then stops then surges up again.

There is something seriously messed up internally in this new carb I think. It's almost like there's a moving part starting and stopping flow in the mixing chamber. Maybe a metal chip or chunk of plastic's in there behind the pressed in ball moving around?
FYI When I had the bowl off changing the needle and seat the bowl was dead clean and so was the main needle and needle fitting and its hole. I did re-check fuel flow at the fuel line and there's lots, continuous, very steady flow.



I've had enough, this crappy carb's going back to the suppliers for refund. If I can find a used carb from a Stakker or someone else I'll fit that, otherwise I'll try and find a new engine. Oh, but there's a complication....

.....This blower takes the auger/impeller drive off the crankshaft but the drive wheels take a half engine speed drive off a pulley on the camshaft running opposite rotation to crankshaft direction. Does anyone know of any new 5 or 8 HP engine maybe a China made one that has the camshaft pulley and crankshaft pulley? Unless I can find one that does, I'll have to rig some sort of reversing speed reduction rig to get suitable drive to the the drive wheels belt. I really don't want to put that kind of time into this thing though. Any thoughts?

Thanks Jeff
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Old 01-28-2018, 02:02:27 AM
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Default Re: Tecumseh HS50 New Carb Troubles

How well does it idle? There is a metering pin in the idle circuit that sometimes hangs up but this will cause it to cavitate at idle rather than flood which yours sounds like its doing. Sounds like the float is sticking in the down position and flooding the bowl with fuel and its going up the emulsion tube. If the engine wasnt running it would prob pour out the carb. I would say warranty the carb its prob just a defect. Ive had decent luck using OEM Tecumseh carbs over aftermarket. Just had two bad ones in a row for a Briggs engine in a Toro CCR machine because the customer didnt want to spend the $125.00 for the Walbro carb.
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Old 01-28-2018, 09:08:52 AM
Greg Mosley Greg Mosley is offline
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Default Re: Tecumseh HS50 New Carb Troubles

Greetings j dayman , The brass float has potentially almost solved your issues (not quite). If you have a float scale weigh them both. My guess the brass will be indicated as heavier which in turn allows the fuel level to increase within the bowl. (Also more prone to float bounce from vibration and incoming fuel turbulence. Thus momentary flooding issues at high idle Try lowering the float setting in very, very small increments to eliminate fuel surging. I am sure the aftermarket has had some internal modifications such as orfice/jet size or positioning for use of the composite float. Good luck. ( I would also be sick of this POS by now also) The beauty of fuel injection, Ahhhh but that's another story...., Enuf Said.
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Old 01-28-2018, 03:47:00 PM
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Default Re: Tecumseh HS50 New Carb Troubles

See if the supplier you got it from will warranty it, I'm still a Tecumseh dealer and have sold many OEM carbs over the years and never had an issue with them yours may just be a rare defect, the company will warranty them no problem just make sure you have your original box as they usually want the manufacture date numbers on them so they can see if there is an issue in a particular run.

The Tecumseh carbs are still manufactured by certified parts corp in the USA , they redid all the old molds from tecumseh as when they bought the company everything including the tooling was pretty much crapped up and needed replacing.

If you were in the us I'd be glad to help you out but with $24 shipping and import fees it would probably be a deal breaker , I stock about 30 of Tecumseh's most common carbs and all the kits and parts you would need.
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Old 02-01-2018, 04:49:11 PM
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Default Re: Tecumseh HS50 New Carb Troubles

I too, recon the brass float is heavier than the cheap plastic one. If you turn the carb in, be sure to retain your float and the new parts you have.
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