Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Hi,

My recently bought (second hand) Ariens ST504 won't start anymore. It used to be really easy to start. Throttle on 50%, full choke and three pushes on the primer and it would start on one or two pulls. It was the neighbor who drove it the last time so I don't know how it acted last time it ran but the neighbor didn't mention anything until he tried to start it next time.

Anyway, now it won't start no matter what. There's fresh petrol in the tank (maybe a bit too much). I've tried having the lid off the petrol tank when starting but that didn't help. The spark plug gets oily after I tried starting a couple of times and after cleaning it I can get it to *almost* start. A few puffs of pretty black smoke and then it dies. Then, the spark plug is all oily again. I checked that there is a spark and it seems fine. Probably time for a spark plug change but it seems wierd that it died so suddenly, no? 

When pushing the primer, it sounds and smells like fuel gets through but I don't know how to check the fuel line better. I haven't starting taking the covers off to check the eninge more but I was hoping to get some pointers before doing that.

So, any ideas?

/Ola, Sweden

One more thing. I checked the oil and it was about half-filled but had a distinct smell of petrol. Not very much but enough to be noticed. Maybe there was not very much oil in there to begin with and that's why it isn't over-filled if any petrol has been forced into it.

I'm going to change the oil regardless because it has not been done this season and I don't know how long the previous owner has run on this oil.

Got a new spark plug. They didn't have Champion's so I got the NRK replacement. No difference in behavior, more difficult to start with the new spark plug and dies after about the same time. Now my arm is too tired to get it started again :o)

The NRK spark plug has a smaller gap, 0.60 mm than the Champion's 0.75 mm. Should I open the gap slightly on the new plug or leave it as it is?

Ola - I'm thinking that you loosened up a stuck float condition. Now, you have just the opposite problem - I believe your carb is running lean! If you have adjusting screws for hi & lo speeds, turn each one counter clockwise a 1/2 turn & see if that helps. If not, remove the bowl bolt. Those small holes in the bowl bolt are what meter the fuel & are probably clogged. Run a small, thin wire thru them & spray them good with carb cleaner. Put the bolt back & attempt a restart. If the engine now runs rich again, turn each screw clockwise (to their original positions) to lean it out. You're getting close! DEFINITELY change that oil!

Marty

Now I'm at a loss.

Today, I get no spark. Tried both the new and the old spark plug and nothing. So I checked with a "spark checker", whatever those are called. The kind of lamp you connect between the spark plug and the spark plug wire. I tried it before and it worked but today I get nothing from it.

I checked for electrical connections and got a bit confused:

The black wire that comes out from under the pull-start cover and that connects to the black lead to the ignition switch is always grounded. Should it really be like that? I thought setting the ignition to "off" grounded that wire by connecting it to ground via the red lead from the ignition switch. I.e. ignition off = black wire from under the cover, via the black wire to the ignition and then to ground via the red wire. Turning the key breaks the grounding via the red wire and the engine can start. Am I wrong here?

If I'm right, what do I do about this? Sounds like  it's time to take it to a professional because new electrical parts isn't readily available here. Also, since everything is under three layers of cover, I don't even know where the coil and magneto is located on this engine. Or maybe it's just a case of corrosion and I should try to repair it myself. If so, what are the steps I should take?

This thing is really haunted... Now it seems like I've managed to break my spark test lamp. So there *may* a spark. However, I can see no spark from the spark plug when I take it out, ground the tip against the engine top and then pull the starter cord. Maybe it's a so much fainter spark than the one from a car that it can't be seen with the naked eye.

Should I be able to see a spark when grounding the tip of the spark plug and pull the start cord?

Should the wire coming out from under the start cord be grounded all the time?

No answers to these two questions?

ofranzen wrote:

You should be able to see a spark.  The wire from under the flywheel shroud should NOT be grounded all the time - if it is, you have no spark due to the ignition coil being grounded!

Marty

Thanks for your replies Marty

So there's something grounding the coil all the time then. Any ideas on typical spots to check for corrosion or other problems? The ignition system is terribly well hidden but I'm guessing that taking the entire engine apart is the next step in getting this running.

Accessing the coil should be easy if the engine doesn't have points & condensor. Once the starter housing (flywheel shroud) is removed (only 4 or 5 bolts need to be removed), it should be right there in plain sight. If it is, remove the little wire going FROM the coil to your shutoff switch. NOW check for spark. If you have no spark, the coil is bad. If you get spark after removing the wire, then that wire is shorting to ground somewhere or the switch near the throttle is grounded - also make sure the metal carb cover isn't touching the shutoff lead that the throttle touches when it's in the off position.

Marty