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Tecumseh 8.0 HP Carb Adjustment


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01-09-02, 02:23 AM   #1  
Tecumseh 8.0 HP Carb Adjustment

I have a 8hp tecumseh engine on a snowblower. It was running very roughly, backfiring a lot and stalling unless I kept choking it. A small engine shop suggested that I clean the carb. The carb is a bowl type. I bought a kit and replaced the key parts (main bolt with screw that holds bowl, square pin and support clip along with rubber support for square pin, black adjusting screw) and cleaned it all with carb cleaner.

Now I can't get it started. I am sure that it is related to the adjusting screws on the carburator. From what I can see, there is one that is attached to the brass bolt that holds the bowl and a black one that goes into the carb. I set them to what they were set to before the cleaning (each one about 1 1/2 turns from tight).

Somebody suggested that the timing may be off. Last year, I sucked up a rubber mat with the snowblower. This caused the motor to stall. I am wondering if I sheared the flywheel key and the timing is all screwed up. My small engine repair shop said that this was very unlikely as these motors have electronic timing. If this is a possibility, how do I access the flywheel to see if this is the problem. I used it quite a lot after I sucked up the mat last year, and I never noticed any serious engine problems after that but I think that maybe it was not running as smoothly as before.

What do you suggest? Which screws on the carb set the low and high speed?

 
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01-09-02, 02:49 AM   #2  
Not likly you sheared the key, but it might be pushed enough to put the thing out of time. Another thing to check is the screw that holds on the carberator float bowl. There is a little hole down in the threaded portion that has to be cleaned out. The best tool for this is a set of gas welding tip cleaners. If you have to get to the flyweel, the shroud cover has to come off, and then the starter clutch. There is a groove that mates up between the flywheel and the crankshaft. The key is there. Look to see if the sides of the groove line up. Odss are the key is pushed. Looking at what the repair shop told you, look for another repair shop.

 
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01-09-02, 08:58 AM   #3  
Fisher
It sounds like you put a new main jet/bowl nut on and a new
inlet needle and seat. How did you remove the old seat?
The brass float is what shuts of the incoming fuel and if
you did not remove the old seat or check the float height or
check the adjustment prior to reassembly, you may have no
fuel coming in at all. It sounds like your original problem
was a slightly clogged jet. Is the new jet identical to your old
one? Timing is probably not your problem here, but a partly
sheared flywheel key is a problem.
Remove the screw in the bottom of the carb and fuel should
dribble out.
Let us know.
Fish

 
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01-10-02, 01:41 AM   #4  
I removed the old seat for the inlet needle by accident when blowing out the carb with my compressor. I had actually reassembled it all without replacing the old seat and as you can imagine, once I connected the fuel line it was "peeing" gas through a small hole in the carb. That's when my small engine shop mentioned that I had probably forgotten to replace the seat.

So I took it apart again, replaced the seat and now it does not pee anymore.

I can tell you that the bowl does fill with gas (when i press on the drain plug there is gas in it. And I'm pretty sure that the brass float is shutting off the gas flow. The parts I used, were identical to the ones I removed (tecumseh parts and the correct model number...).

Fisher wrote "Timing is probably not your problem here, but a partly sheared flywheel key is a problem."
Would a sheared flywheel key (assuming that it is sheared) impact the timing and hence the ability to start the motor? I want to try and focus on one problem at a time. The whole sheared flywheel key thing is only speculation at this point.

Fisher wrote "Remove the screw in the bottom of the carb and fuel should dribble out."
Which screw in the bottom of the carb? The one that goes into the brass bolt (not really a normal bolt) that holds the bowl? Is this different than pressing on the drain to see if the bowl is full?

Again, any more help is appreciated.

 
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01-10-02, 01:52 AM   #5  
Fisher is indeed talking about the "bolt" that holds on the bowl. Did you replace that. If you didn't make sure that the hole in the threaded portion of that is open. Take your compressed air and blow into the top of the "bolt" and make sure that air is flowing thru the hole. If not take a small screwdriver and clean out the inside and then clean the hole. You might also want to tale a small wire and poke up into the tube taht comes down from the carb.

 
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01-10-02, 02:23 AM   #6  
I did indeed replace the "bolt" that holds the bowl, it was part of the "kit" that I bought. I also replaced
-the square pin that attaches to the float with a wire
-the wire
-the gasket that the tip of the square pin seats into to stop the gas flow
-the rubber gasket that prevents the bowl rim from leaking
-the black plastic screw (or needle?) that regulates the gas (is this the high speed adjustment screw?) and the rubber gasket on this screw
-the shiny dome on the inside of the carb

I'm going from memory and I don't have the parts in front of me but I think that's it.

 
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01-10-02, 05:19 AM   #7  
Fisher
I would start from square 1. Remove the plug and reattach the
wire and lay the plug against the metal of the block and
pull the rope and check for spark. If you have spark, pour a dribble of fuel in the plug hole, reinstall the plug then try to start.
If it starts then dies, then you still have a carb problem. Do
that and then tell us what has happened.
Fish

 
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01-13-02, 03:24 AM   #8  
Success!!!!

I did what you recommended, started from square one. Put fuel into the cylinder, cranked it, it started and sputtered, repeated this and it started and kept running. Adjusted the bottom screw for high speed and the side screw for low speed. It now purrs like a kitten. It turns out that I did have the carb reassembled correctly, just didn't try hard enough to get it started.

Thanks to all who helped out. Just curious though, who is making money (if anybody) on this board? Either way, sure do appreciate it.

 
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01-13-02, 05:40 AM   #9  
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