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917.377591 mower engine hesitates/engine rev's cycles/oscillates up down

#1

I

induray

Irecently rebuilt the carburetor, and a while ago replaced the solid state ignition of a Tecumseh 6.75 HP engine. The problem is that now it is moderately hard to start. After it starts, the engine cycles up and down until it warms up(engine rev's oscillates up and down). The power seems a little bit low.

Any suggestions???


#2

R

Rivets

You need to clean the carb again. This time make sure that both the high speed jet and the idle jet is clean and clear in both directions. The high speed jet is built into the float bowl nut. The idle jet is located on the side of the carb, under a plastic cover. This jet is extremely small, and is probably plugged. I use either the retaining wire from a float needle or raid my wife's sewing kit for a very fine needle. Make sure that when you spray carb cleaner into the ends you see it coming out the side ports.


#3

I

induray

Rivets said:
You need to clean the carb again. This time make sure that both the high speed jet and the idle jet is clean and clear in both directions. The high speed jet is built into the float bowl nut. The idle jet is located on the side of the carb, under a plastic cover. This jet is extremely small, and is probably plugged. I use either the retaining wire from a float needle or raid my wife's sewing kit for a very fine needle. Make sure that when you spray carb cleaner into the ends you see it coming out the side ports.
Click to expand...

Thanks Rivets. Have you experienced this? I want to be sure before I proceed?


#4

R

Rivets

I think so. I taught engine repair for 30+ years and have worked in repair shops for over 25. I don't remember everything at my age, but I think I have done these steps a couple of time. I also know that there is no harm in asking this question. :laughing::laughing::eek: good luck


#5

I

induray

Rivets said:
I think so. I taught engine repair for 30+ years and have worked in repair shops for over 25. I don't remember everything at my age, but I think I have done these steps a couple of time. I also know that there is no harm in asking this question. :laughing::laughing::eek: good luck
Click to expand...

Do I have to remove the welch plug again? I remember going(Cleaning and using pressure air) thorougly thru the idle mixing well because if I didn't do it right the first time, I would have to buy another plug. Is a Tec Vector Carb.
http://outdoorpowerinfo.com/repairs/tecumseh_vector_carb.asp


#6

R

Rivets

No, please post the model numbers of the engine and I'll see if I can find pictures to help.


#7

I

induray

Rivets said:
No, please post the model numbers of the engine and I'll see if I can find pictures to help.
Click to expand...

Ok the Craftman is a 4 cycle engine model no. 143.986700

Here is a link to the Vector carb- click on it:
Disassembly, Cleaning and Repair of Tecumseh Vector Carburetor

Thanks for the help


#8

R

Rivets

Sorry, I thought you had a different carb. When you cleaned the carb, did you install a new carb kit? I know Tecumseh changed the main nozzle in their rebuild kits a few years ago. If you didn't install a new kit I suggest you do so.


#9

I

induray

Rivets said:
Sorry, I thought you had a different carb. When you cleaned the carb, did you install a new carb kit? I know Tecumseh changed the main nozzle in their rebuild kits a few years ago. If you didn't install a new kit I suggest you do so.
Click to expand...

Yes I did. I replaced the the emulsion tube, o-ring and sprint and bowl gasket, and other parts.I replaced the air cleaner body with the primer bulb. I did a full overhaul! See my past thread under Induray.

I will try recleaning the carb again.

Question..Does the governor has to do with adjusting the engine's rev??


#10

R

Rivets

I'm willing to bet that you did not get the tube tightly fitted down when you installed it. I don't like this design and it has happened to me more times than I like to admit.
The governor controls the top engine speed. Normally has nothing to do with surging, unless it is set too high.


#11

I

induray

Rivets said:
I'm willing to bet that you did not get the tube tightly fitted down when you installed it. I don't like this design and it has happened to me more times than I like to admit.
The governor controls the top engine speed. Normally has nothing to do with surging, unless it is set too high.
Click to expand...

Ok. Will do that.
Not too happy though...but I trust your experience over mine:smile:
Need a drink


#12

I

induray

Rivets said:
I'm willing to bet that you did not get the tube tightly fitted down when you installed it. I don't like this design and it has happened to me more times than I like to admit.
The governor controls the top engine speed. Normally has nothing to do with surging, unless it is set too high.
Click to expand...

I just strted it and pushed against the governor ti prevent it from rotating. The mower was stable. I pushed against the spring tension. I wonder if the spring has lost its "springiness"?


#13

R

Rivets

I'm burned out on this, and I don't know what to tell you any more. Sorry.


#14

L

lawngnome

I was told by a mower repair guy that normally when this surging happens most times the carb is shot.on your smaller carbs. No amount of cleaning or rebuilds can fix it.
But i just experinced a blown head gasket causing a surging problem. On a larger motor but same problem. My $.02


#15

R

Rivets

Lawn gnome, get a new repair guy. This guy is going the easy way out and substituting parts. If I have cleaned or rebuilt one carb I have done a thousand. Only about 10% need to be replaced. This guy gives good honest mechanics a bad name.


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