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345 backfired died and won’t start

2547 Views 9 Replies 7 Participants Last post by  denverguy
I did a little service work on my 345 and it was running great. The next time I went to run it, it started right up, ran for about two minutes, backfired and died. Now it won’t start at all.
The service work included: new plugs, new air filter, oil filter, oil change, new carburetor, new valve cover gaskets (they where leaking), new fuel pump, new fuel filter, cleaned fuel tank and lines and filled with fresh fuel.
Any suggestions?
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Wow, lots of stuff. I would start with the fuel line to carb. Are you getting fuel? Next would be remove the new carb and install the old one. Also check for spark but suspect a fuel issue. Perhaps others will have suggestions.
Dave, I agree with Farmer IF your engine turns over! While performing your work, you may have loosened a connection or blown a fuse. Also, with a new carb, bowl will be empty and will take 2 or 3 minutes to refill. So:
Does it turn over?
Do you have mechanical or electric fuel pump?
Do you have a spark tester?
Do you have a multimeter?

Sorry for the questions, but "won't start" is kinda vague! Bob
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So, I have spark.
It turns over just fine. Has a little ‘popping’ noise but no go.
I have a mechanical fuel pump and it is working fine. Getting fuel to the filter and the carb.
Just to clarify, after all of the work I did on it, it ran great for the whole mow (about 3 hrs worth). It didn’t stop working until the next week when I started it and pulled it out of the barn. That’s when it backfired and quit.
Farmer52, I tried the carb swap and still have the same results.
Let me know if ya think of something else.

Thanks for all the help, I’ll take it. I don’t know much about small engine stuff.
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You need a compression tester and a test.

Is it an 18hp 345 with a plastic camgear?
rydplrs, I don’t know the answer to that but I will check.
I don’t have a compression tester so I’ll also need to check into that.
If you don't have a compression tester, you can verify if the cam is broken by removing one of the valve covers, crank the engine over several times, and watch the rocker arms. No movement would indicate the cam is not rotating. The older ones with the plastic cam gear do eventually break or strip the teeth.

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My JD 285 would not start and it was the plastic cam, 7 teeth, all in a row had broken off. No backfire, just did not sound right when turning over.
Thanks for the input, I’ll pull that cover and check. I read something about aluminum rods going bad as well which I’m assuming could cause the same issue. Any thoughts??
How hard is it to change the cam? I’m pretty good with mechanical stuff but I don’t have much in the way of small engine specialty tools. Does it require any special stuff?
Sure appreciate the help on this. I’ll let you know what I find.
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There a couple of youtube videos on changing the cam.

Your symptoms are consistent with a failed plastic cam gear. If you don't have a compression tester, you can pull a valve cover to see if the rocker arms move while cranking as Tommyhawk suggests.
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