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Bolens H16x1 Tecumseh Oh140 Walbro Lmh Carb Help Needed


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#1 Nascar3244888 OFFLINE  

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Posted March 18, 2013 - 07:00 PM

I am really starting to get frustrated with this old Bolens.  Its a 1983 Bolens H16x1 Hydrostatic garden tractor with hydraulic lift.  I got it last year and was able to get it running after many years.  I have always had a problem though.  I just cant seem to get the carb adjusted to where it runs good at all speeds.  I can get it to run fairly well at full throttle, but anything below half throttle it back fires out the carb, sometimes so much so that a flame comes out, and it runs really rough at anything below 2/3 or half throttle. add some choke and it helps some, but not totally.  I have totally rebuilt the carb minus the tube that runs up threw the middle into the throat.  I read afterwards that this tube is to be replaced if removed, problem is I cant find any to replace it with.  So I found another carb and rebuilt it but this time i did not remove the center tube, and it runs just the same.  I even went as far putting an adjustable main jet in the one carb the I did not take the center tube out of and it runs the same with that,( the original carbs had fixed jets ), Its like nothing I do seems to help. When I bought the tractor the engine had no compression, turned out to be a out of adjustment valve, after resetting the valves then, and re-checking them today they are still at the correct specs .005, and .010....Compression 173psi.  Im really lost at what to do next....Please Help!!!

 

 


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#2 farmerall ONLINE  

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Posted March 18, 2013 - 07:07 PM

Maybe one of the very small idle circuts in carb are clogged? Does the engine have a fuel pump, if it does maybe it doesn't pump well enough at a low idle. I don't have much experience with Tec engines so I can only take a guess.


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#3 chris m ONLINE  

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Posted March 18, 2013 - 07:14 PM

If it is back firing through he carb I would think it is either a timing issue or a bad or loose valve seat. Have you pulled the head yet?


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#4 DH1 OFFLINE  

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Posted March 18, 2013 - 07:15 PM

You probably already checked this but is the float level set right and is the float itself good, no pin holes in it?


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#5 8tyman8 OFFLINE  

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Posted March 18, 2013 - 07:55 PM

I have had the same problem with my carb ... there is a clog in the low speed circuit and Normally you can't get it cleaned and for the Non reusable emulsion tube if you chuck it up in a drill you can turn it (like in a lathe) use a file to cut a V or a U into the spot where there is a small hole My suggestion if find another carb .. unless you can get it clean (VERY difficult on a lmh) for the reason they use Very small circuits... 

(picture of modified tube)

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Edited by 8tyman8, March 18, 2013 - 08:04 PM.

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#6 chris m ONLINE  

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Posted March 18, 2013 - 08:07 PM

I am just leaning to something other than a carb problem. only because you have used multiple carbs and had the exact same issue.But there is always the possibility like stated above that both carbs are plugged in the idle circuit?


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#7 chris m ONLINE  

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Posted March 18, 2013 - 08:16 PM

Maybe one of the very small idle circuts in carb are clogged? Does the engine have a fuel pump, if it does maybe it doesn't pump well enough at a low idle. I don't have much experience with Tec engines so I can only take a guess.

Matt(TacoTuesday) that is a great point! I wasn't even thinking that this engine might have a fuel pump :wallbanging: So if it were my engine I would also check the fuel pump like Matt (TacoTuesday)suggested, Good luck and Thanks again Matt (TacoTuesday) :thumbs:


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#8 New.Canadian.DB.Owner ONLINE  

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Posted March 18, 2013 - 09:20 PM

So, if you have a 1983 Bolens H16x1, then you should have a OH160-170089A engine.  The OH140 was used on the H14XL.  If you've been buying carb kits for the OH140, that might be part of your problem.  And yes, the parts list shows a fuel pump.

 

Edit: P.S. I vote timing.  Two carbs with the same failure is to coincidental for me.  Fire out the carb says ignition prior to TDC.  Although, a sticking intake valve would have similar results, but it would be hard to get a compression reading of 173.  Flywheel key is where I'd start.  


Edited by New.Canadian.DB.Owner, March 18, 2013 - 09:57 PM.

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#9 EricFromPa ONLINE  

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Posted March 18, 2013 - 11:45 PM

Backfiring through the carb sounds like more of an Ignition timing issue or improperly adjusted valves.


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#10 superaben OFFLINE  

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Posted March 19, 2013 - 06:58 AM

At first, it sounds like your carburetor is too lean.  A similar thing happened on a Gravely L I was working on, but a Zenith carburetor.  It carry on like a pile driver unless it was blowing away at 2500+ RPM.  I had two problems, there: adjustments too lean, and a bad idle needle that had gotten bent.

 

Is the throttle shaft good?  Gasket to block/manifold or air filter?  Air filter itself? Air leaks will ruin your adjustments at low (er) speeds.

 

You've got good compression, and we'll assume that the carburetor is spotless.  What about the spark?  Bad spark will cause the motor to run poorly.  Have you chucked in a new spark plug just to test?  The OH140 had that huge solid state ignition, right? so no condenser and points. 

 

By the way, not to market, but if you need the jet that 8tyman was showing, I've got a few NOS #30355 Walbro jets that need a home as well as other Walbro parts.  I also have a NOS solid state marked "used" that you could have to try if you want to dig that far in.

 

Ben W.


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#11 Nascar3244888 OFFLINE  

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Posted March 19, 2013 - 08:54 AM

Maybe one of the very small idle circuts in carb are clogged? Does the engine have a fuel pump, if it does maybe it doesn't pump well enough at a low idle. I don't have much experience with Tec engines so I can only take a guess.

 

Yes it does have a fuel pump, I never thought of this until now but there was a different kind of fuel pump installed on the one carb, I just swapped it over to the original one that came with the tractor but I will try and use the other one to see what happens...Thanks

 

If it is back firing through he carb I would think it is either a timing issue or a bad or loose valve seat. Have you pulled the head yet?

 

I have not pulled the head and would like to leave that as a last resort because it is a really in depth job...Thanks

I have had the same problem with my carb ... there is a clog in the low speed circuit and Normally you can't get it cleaned and for the Non reusable emulsion tube if you chuck it up in a drill you can turn it (like in a lathe) use a file to cut a V or a U into the spot where there is a small hole My suggestion if find another carb .. unless you can get it clean (VERY difficult on a lmh) for the reason they use Very small circuits... 

(picture of modified tube)

 

Sounds like a possibility, I would love to get another one instead though....Thanks

 

So, if you have a 1983 Bolens H16x1, then you should have a OH160-170089A engine.  The OH140 was used on the H14XL.  If you've been buying carb kits for the OH140, that might be part of your problem.  And yes, the parts list shows a fuel pump.

 

Edit: P.S. I vote timing.  Two carbs with the same failure is to coincidental for me.  Fire out the carb says ignition prior to TDC.  Although, a sticking intake valve would have similar results, but it would be hard to get a compression reading of 173.  Flywheel key is where I'd start.  

 

You are correct it is infact an oh160, that is a misprint on my part, As far as the flywheel key goes,  it would have to be a last resort to check that as the engine would need to be removed....Thanks

 

At first, it sounds like your carburetor is too lean.  A similar thing happened on a Gravely L I was working on, but a Zenith carburetor.  It carry on like a pile driver unless it was blowing away at 2500+ RPM.  I had two problems, there: adjustments too lean, and a bad idle needle that had gotten bent.

 

Is the throttle shaft good?  Gasket to block/manifold or air filter?  Air filter itself? Air leaks will ruin your adjustments at low (er) speeds.

 

You've got good compression, and we'll assume that the carburetor is spotless.  What about the spark?  Bad spark will cause the motor to run poorly.  Have you chucked in a new spark plug just to test?  The OH140 had that huge solid state ignition, right? so no condenser and points. 

 

By the way, not to market, but if you need the jet that 8tyman was showing, I've got a few NOS #30355 Walbro jets that need a home as well as other Walbro parts.  I also have a NOS solid state marked "used" that you could have to try if you want to dig that far in.

 

Ben W.

 

Both carbs I have tried had new gaskets installed in the carb as well as by the intake but only on the outside of it, throttle shafts are fine, i was spraying around the carb with starting fluid as well as near the gaskets where the carb mounts by the intake and no increase in speed, or change in the roughness of the engine running,  I have tried different spark plugs as well, as for the NOS parts you have, I would like to buy 2 new emulson tubes and 2 new carb kits for these carbs again, can you send me a PM on the prices of those items please, THANKS

 

 

 

 

First thing I am going to do is make a video of how this runs before I tear into anything else, I am going to make a series on this that way if we can figure it out maybe it will help others as well.  Thanks for all the help so far and I will be giving updates along the way


Edited by Nascar3244888, March 19, 2013 - 08:56 AM.

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#12 8tyman8 OFFLINE  

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Posted March 19, 2013 - 11:51 AM

Way to tell if its the carb or not Get a Windex or spary bottle put some fuel in it and spray some in the carb well running Under 1/2 - 1/4 throttle ...BE-CAREFUL that it does not back fire and burn you...  if it runs better its the low speed circuit (VERY common on the Lmh carbs) and VERY hard to clean if its totally plugged (normally are) I would also check the SOLID STATE PIN's in the fly wheel one is longer than the other i got a fly wheel that one Flew out of and it may be running with the spark timing advanced How does it start ? ever kick back ? 


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#13 HowardsMF155 OFFLINE  

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Posted March 19, 2013 - 12:31 PM

Way to tell if its the carb or not Get a Windex or spary bottle put some fuel in it and spray some in the carb well running Under 1/2 - 1/4 throttle ...BE-CAREFUL that it does not back fire and burn you...  if it runs better its the low speed circuit (VERY common on the Lmh carbs) and VERY hard to clean if its totally plugged (normally are) I would also check the SOLID STATE PIN's in the fly wheel one is longer than the other i got a fly wheel that one Flew out of and it may be running with the spark timing advanced How does it start ? ever kick back ? 

Double check the timing pins.  It may be that it's only firing on the delay pin, which would be more likely to cause backfire issues. I had to troubleshoot a nice running but poor power output Techumseh last year, turned out the main pin was not high enough for the spark to sense it so it was running on the delayed timing.

 

Here is my thread when trying to troubleshoot my problems.  It may help or not.

http://gardentractor...ne-lacks-power/


Edited by HowardsMF155, March 19, 2013 - 12:43 PM.

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#14 Nascar3244888 OFFLINE  

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Posted March 20, 2013 - 01:58 PM

Way to tell if its the carb or not Get a Windex or spary bottle put some fuel in it and spray some in the carb well running Under 1/2 - 1/4 throttle ...BE-CAREFUL that it does not back fire and burn you...  if it runs better its the low speed circuit (VERY common on the Lmh carbs) and VERY hard to clean if its totally plugged (normally are) I would also check the SOLID STATE PIN's in the fly wheel one is longer than the other i got a fly wheel that one Flew out of and it may be running with the spark timing advanced How does it start ? ever kick back ? 

 

Just started it up today, and she fired right up and ran well after smoking really badly for the first 30s seconds, no lack of power at full throttle.  I will try the spray sometime soon and see what happens.






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