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LA145 Head Scratcher

3839 Views 31 Replies 12 Participants Last post by  midwesties
I have an LA 145 that is driving me crazy and I'm hoping someone can point me in the right direction.
Here is the problem. I got this tractor which had been sitting a while and I got it basically from an estate sale. The engine has 48 hrs and everything is in great shape. Before I got it the son of the previous owner tried to get it to run but got no where starting it. I cleaned up the carb and was able to get it to run a bit by priming it running gas down the intake however it was obvious the o-rings where dried out. Rather than just buy the o-rings I opted to buy a new carb (just a few dollars more. It now runs good (maybe a sputter here and there) but the only way to start it is to pour gas in the intake. Once I've done that it runs and I can restart it. Once it sits over night I have to prime it again.
So in the interest of saving time: I've checked the gas lines, changed the fuel filter, even tried an electric fuel pump.
There is gas in the float, but it won't start. I admit I don't have much experience with these Briggs 2 cylinders and these carbs are new to me.
Any suggestions, things maybe I missed?
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Ok I saw this early today and been thinking. The first carb did this to but had dry o rings so bought 2nd new carb and still same. It starts and runs if you prime or enrich the mixture and restarts but after cool down needs enriched again to start and run. Ok it restarts cas it's hot and doesnt need the enriched mixture so somewhere it's not pulling the choked fuel in to start normal. Like not enough vacuum to pull it.
Try what Tony said and cover the carb and see if it trys to start better than just holding choke closed I'm betting it will try and fail maybe a little better than just hand on choke butterfly. It does sound like a vac leak something you had before the carb replacement. Just enough to not start cold but run hot. I'll bet when it does start an running it's way could pull a plug and see the color of plug.
If it is you've got to find the leak, gas in q spray bottle can sometimes work but you have to be careful VERY CARFUL and listen carefully for any increase in rpms.

If you dont find any leaks it's still sounds like a vac problem. The motor in simple terms a pump so would low compression or valve lash not set right cause this also?? idk

Anyway keep us updated.
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Update on my situation with this same problem.

So, I replaced the intake gaskets, still nothing. I took off the air filter cover and covered the intake with my hand, still no cold start. I also blew out the fuel lines, and replaced the fuel filter (again) just in case. If I prime it, starts right up and stays running. It will only start back up without being primed if I run it for 15-minutes or more.

Previously, I replaced the following:

- plugs (correct gap, verified spark)
- fuel pump (verified it is working correctly)
- carb (new gaskets came with it)and solenoid (verified solenoid is getting 13 volts)
- air filters
- fuel filter
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Is the throttle plate in carb all the way open when mower us off and when you crank to try to start it?
Your engine may be low on compression. I would do the compression test and also check valve lash.
I too have completely covered the intake to no avail. I too can restart once it has been started however I can usual start up to an hour or more later.

I really don't think compression is an issue as the engine has 48 hrs on it but I'll check it. I've tried everything else.
I'm leaning toward compression or valves as you did say it had sat for a while. a broken or stuck ring or any number of problems with the valve train could have occurred when the previous owner's son just cranked it over after a long period of inactivity. a compression check and a leakdown test may point you in the right direction.
Something else to consider. You mentioned that the new carb was only a few dollars more than the O-Rings. Sounds like you may have picked up an inexpensive Chinese carb. Some people have great luck with them, others have nothing but problems with them.

Also, your engine likely has a compression release which makes testing compression near impossible. Valve lash shouldn't be an issue on an engine with 48 hours.

I would look hard the carb even though it's new. You also mention changing a number of items but I see no mention of draining and replacing the fuel.

Finally, there really is no place for teflon string when sealing gaskets on the carb or wherever.
Denverguy, thanks for the input. I might be more suspicious of the carb if I didn't have the same problem with both carbs. but you are correct, it could be the card.

Gas was changed on day 1the tank was cleaned, fuel lines changed, filter changed, fuel pump changed.

I wasn't aware of the compression release. Any way that you are aware of around that? Take the rocker arms off?

Teflon string works! An old tractor mechanic showed me on an old ford tractor. I haven't tried it yet. But it worked when he did it.
This is turning into a head scratcher, when you covered the carb did it feel like it had good suction?
Throwing out a random suggestion - pull your carb. compare the carb, the intake, and the gasket. Does everything matchup?
The carbs are virtually identical. I even thought about switching the gaskets and o-rings and using the old carb. But I don't see any advantage to doing that. Maybe if I get desperate enough.
So, I had a guy that fixes up old mowers tell me that it’s the fuel lines. He said that the old fuel lines collapse on themselves and choke out the fuel supply. Makes sense. That’s the next step for me.
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