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craftsman tractor won't start, back fires

Posted by bigjohnsons34 none (My Page) on
Thu, Dec 29, 11 at 21:42

I have a craftsman tactor dyt 4000 model 917.273640 with 18.5 b&s moter. Someone gave it to me so I not sure when it stoped working. I turn the key and the engine cranks but won"t start, than it backfires. I checked the flywheel and it looks lined up right, the key way looks in tact. I took the valve cover off the front and there was oil in there, not sure if that is normal. Took apart the carburator and it lo0oked clean. not sure where I should be looking and what I should be looking for. Thanks for any help


Follow-Up Postings:

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RE: craftsman tractor won't start, back fires

Check for a bent or broken valve push rod. One will be aluminum and one will be steel. Operate the starter and look to see if valve push rods are going up and down.
Check spark plug wires for frayed spots. More help will come tomorrow, i am sure. Borrow a compression tester and check for compression. RJ


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RE: craftsman tractor won't start, back fires

If there wasn't oil under the valve cover, you really wouldn't need the cover-

Have you looked at the spark plug? Considering the price for just one, I'd go ahead and install a new one as a matter of principle.

IF that doesn't help, try spraying a bit of carb cleaner in the air intake while cranking and see if it tries to fire "better".


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RE: craftsman tractor won't start, back fires

Crappy old 17hp intlek single lunger I have on my zero turn a pain in the @## to get started after it has been setting for awhile. Especially after it sets month or two over winter. Dang thing cranks and cranks, pops, and backfires. I always have to prime it to get it started even only after couple days setting.

I've done all the routine maintenance stuff and it still piece of Crap engine. I just live with it priming it before starting. Sometimes I even remove the spark plug and spray carb. cleaner in the comb chamber and motor it over blowing out any liquid which may cause flooding. Then I spary and clean the spark plug with short blast back into the comb chamber before I install the plug. This seems to let it fire right off. But, usually only use this method after long periods of storage or setting.

Sometimes If I leave the key on for 30 seconds to min. this helps. Fuel shut off valve in the carb. opens up cause I hear the click. But, have no clue if this increases fuel flow from just turning and cranking and cranking. mine has one of them weak about worthless diaphramn vacuum fuel pumps on it which IMO probably causes this delima due to the weak pulses when cranking which IMO don't pump much fuel or push the air out of the system to the carb.


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RE: craftsman tractor won't start, back fires

Heh heh, my buddy Charlie had a 46 Ford 5 ton dump truck. To start it, He backed off the air cleaner wing nut and filled the bowl it sat in with gas. Worked like a charm.. I like the old stuff with a gravity feed.


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RE: craftsman tractor won't start, back fires

OP - might check to verify choke butterfly plate closes fully when activated from dash control.....


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RE: craftsman tractor won't start, back fires

I'm not sure if rc wants some thoughts on his engine's problem or just a match!


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RE: craftsman tractor won't start, back fires

A Match!

I tried and checked about everything else including the Valve settings (when they are off alittle it's even harder to get started) Choke. It works (both visual and cause when it does start it I don't pull if off choke it chokes the engine out) Spark plug, good. elect. fuel shut off valve, Both visual and hear it click I noticed sometime is I leave the ignition switch to on for few seconds it sometimes helps) Spark, nice pretty blue spark.

Course the oil has been changed regliously (cause I am the oil changing nerd) This has been a problem since new. I should of took it back and got my money back, but it runs good when it starts and I figured it would get better and oc course my pride and knowledge . 310 hours later still the same. But when I get it started it Run great and don't use no oil.

I'm Just glad I don't have to start it in the cold, I dought I could get it started if temps were close or below freezing?

I suspect it the weak vacuum fuel pump beings the tank is below the carb. and the fuel line run up to the fuel pump and about foot half long. I'm too cheap to just buy another fuel pump when I can get it going by priming it. Yes the fuel lines are like new and tight at the connections. any ideas I haven't already tried? I am always open for suggestions, not that hard headed.


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RE: craftsman tractor won't start, back fires

Well, rc. If you haven't already, set the park brake, pull the line off the carb or put a spare on the end of the pump and crank it over to see if you have pump action. If you do, and from your past description- I wonder if the small solenoid on the bottom of the carb is working freely. Lots more to cover. Let me know your thoughts after you check that out.


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RE: craftsman tractor won't start, back fires

tom thnaks for the ideas, it will be awhile, I'm down right now from hernia operation, second one.


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RE: craftsman tractor won't start, back fires

Yes, RC, wheen you gt back in action, do this: Turn off the fuel line valve, if there is one, or clamp the fuel line to shut off the flow of fuel to the inlet. Then remove that valve on bottom of carb, the one that holds the bowl on, and clean it good. They can and will get gummy in there, and will stick closed, until the constant pull of the electricity allows them to open up. (maybe, if not too sticky) I've seen that problem on several of them-all gummy and stuck from rust and gum!
In fact, i was given a really nice Craftsman lawn tractor, dark green, that had that problem. It'll be a good seller come Spring!
HTH: Rusty J.


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RE: craftsman tractor won't start, back fires

One of the most common problems with the DYT 4000 is valves being out of adjustment. Very simple to adjust them. Some folks adjust them every year. Worth a try. Worked for me with starting and running problems


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RE: craftsman tractor won't start, back fires

Would that also apply if a Kohler engine was in the DYT 4000?


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RE: craftsman tractor won't start, back fires

No, the Kohler engines have defective head bolts and blow head gaskets. The Briggs engines have valves that need adjusting every week.


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RE: craftsman tractor won't start, back fires

Best description ever, wheely_boy!!!!


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RE: craftsman tractor won't start, back fires

Heh, heh, heh! :^)


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