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Discussion Starter #1
I'm having a problem with what i suspect might be fuel delivery in my '84 318 that start after about 20 minutes of my first mowing with the tractor. Before doing that first mowing I had drained and replaced the hydro fluid and filter, no problems there. I also had to troubleshoot and replace a bad voltage regulator, once the new VR and tightened the air-gap to .018 I was good to go. Deck engaged nicely with the switch and the battery light was out.

So I'm cutting along and things are running fine when it starts to lose power like its running out of fuel. Killed the deck and pulled the throttle back, limped it back to the garage and let it sit. Now it starts right away but I get the sense its running really rich and it doesn't want to stay running at full throttle.

Please help. I thought I had this thing ready to go.
 

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THE TRACTOR HUNTER
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Would it start right back up after it shut down after 20 minutes of running?

I typically associate this with a bad Coil getting too hot and then shutting the engine off. But for some reason I can't remember if there is a little coil somewhere on our engines?

If you feel it is a fuel issue, make sure the fuel tank is breathing correctly. Once everything is hot and running, the pressure in the tank could be creating a vacuum lock on the fuel delivery. You can see this if you look at the fuel filter up in the engine compartment and see if fuel is still coming in from the tank.
 

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The Magnificent
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Right now it still won't run at full throttle, after it has cooled down?

Do you have a timing light so that you could verify both cylinders are getting spark?

Can you crack open the fuel filler cap and see if you can run full throttle?

How long had this one sat? Could some junk have become lodged in the carb? Varnish loosened up than clogged everything in its path?
 

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Discussion Starter #4
Thank you for the replies. My first post was a mis-written a bit. After 20 minutes of mowing it started having problems. That was yesterday, today I went to start it and it fired right off, idled good for say 2-3 minutes then died when I hopped on it and tried to raise the deck up to drive it around back to my shed. That load stopped it.

I don't have a timing light, I could get my hands on one though. This mower had sat awhile so I thinking like D-Dogg, that the fuel sucked up some crap and now the carb is having trouble. For what its worth, the fuel filter looks fine.

What next steps would you recommend? Pull the carb and soak it in some Gunk? Do I need to drop the tank somehow?

Any other things to look at?
 

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The Magnificent
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Sorry for more questions, but I'm trying to get an accurate picture before I recommend you spend a couple of hours in the wrong direction.

Today it started and idled (until you tried to move the tractor)?

Idled with the choke off?

Will it restart?

Will it idle for 5 minutes?

What is the max no load RPM? 1/4, 1/2, 3/4, full throttle?

If you go to half throttle and the engine begins to die, does applying the choke bring it back?

Will the tractor move at say half throttle with the choke on either partially of fully?

Any backfiring or shuddering as if hitting on only one cylinder?

And this is fresh gas, isn't it?
 

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Discussion Starter #6
No apologies! I appreciate the effort. Ok so I went out just now (about two hours from my last attempt) to start the tractor. It fired off as normal with the choke about half-full way out but it was a black smoky start. It idled at about a third throttle for less than a minute and died, now it doesn't want to restart.

Last night it backfired once when it but hasn't since. I tried to move it earlier and it died under the load.

The gas is new 91 octane as of last week. I tried to find a station with non-oxy fuel but wasn't able too so its 10% ethenol blend.
 

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The Magnificent
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I run regular in mine, but that's not the issue here.

BTW, this fuel filter - is it a real JD filter or a generic you grabbed somewhere? This is a low pressure fuel system and an automotive type or a filter for a higher pressure fuel system may restrict fuel flow.

Do you happen to have a multi-meter? Is that timing light which you could borrow close by? If not, you can press on with a couple of tests.

First of all, check your fuses. My neighbor's 318 was acting all weird and not starting or not staying running, and it was a dirty corroded fuse holder. Cleaned it up and he was golden.

While the engine will not start, pull a spark plug and replace the plug wire. Lay the plug against something metallic such as a heat shield and crank the engine while you observe the plug. Spark/no spark/week spark/nice hot blue spark? Repeat for the other plug just for fun.

One plug sparking and the other not would point to a bad plug or wire. easy enough to swap around to see.

Neither plug sparking or a very weak spark could point to a bad coil, condenser or mis-adjusted points. We'll rule out point adjustment since it had been running.

Now for this test, you need to observe very carefully. With the plugs still out and grounded, turn the key to the on position, bump the starter and then switch off and look for a single spark. That would mean the coil is creating a spark when the 12 volts from the battery is removed, as it should. You may have to repeat this test a couple of times to get a good indication.

If you seem to have spark when the engine won't start, and even choking the heck out of it doesn't help, you can drip just a couple of drops of gas down the carb (and replace the air cleaner in case of backfire), and see if she will crank.

This pretty much points the finger at a fuel delivery problem.

You can try gently rapping the float bowl a few times with a screwdriver handle to see if you have a stuck float.

Next you can try a fuel flow test by removing the fuel line to the carb and holding it over a small container (a graduated container would be ideal) while cranking the engine. Crank for maybe 10 seconds and see how much fuel you get. It won't be a lot in a functioning system but anything over a couple of ounces should be good.

Thats a good half hour's work so let us know what you come up with.
 

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Discussion Starter #8
I got a little time on this evening and did the fuel pump test. I pulled the hose from the carb and held it into a bottle. It put out plenty of gas for the few seconds I cranked it so I don't think lack of fuel is the issue (nor do I think its getting too much.)

I wasn't able to get to checking spark tonight. What tests did you have in mind for the multimeter?

The fuel filter was replaced by the PO who put it in along with some carb cleaning in between test drives to help it run better. There was a deere dealership right on the way to his place so I think its a deere part. i wrote down what is should be and I'll compare that to what it is.

Thanks a million, with the forums help I'll get this thing running like a champ. Hopefully then help the next guy in my shoes now.
 

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The Magnificent
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The fuel filter was replaced by the PO who put it in along with some carb cleaning in between test drives to help it run better.
So the tractor had a potential fuel problem even before you bought it?

With the multi-meter I was going to recommend you perform a coil resistance test while the tractor was in a non-starting state.
http://autorepair.about.com/od/troubleshooting/ss/coil-test-ohm.htm

If the coil was good, I was going to get to to verify your points are opening and closing correctly by using the resistance scale and measuring between the black coil wire (with it disconnected from the coil)and ground while cranking the engine.

If the gas in the carb or starting fluid (would be safer) test while the tractor is in a non-starting state will start the engine even briefly, then I would next suggest you get the carb rebuild kit from Deere and just go ahead and do a rebuild with a new float needle and seat. Maybe even spring for a new float. You can soak the carb if you like, or use spray cleaner to clean it up.
 

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Discussion Starter #10
Some history that may help. When I first test drove the tractor (a Monday 7/6) it ran well but the idle started searching before shutting it down. The PO said he cleaned the carb and replaced the fuel filter before I came back Wednesday and test drove it and subsequently purchase the 318. It ran well on Wednesday (minus the air-gap problem now fixed.) I got it home ran it around the drive-way and street a bit and then Thursday I cut the lawn with it (20 minutes). The motor ran well but the battery light was on. I decide the smart thing to do was fix the electrical, replace the blades, change fluid and filter in the hydro before cutting again.
The tractor ran like a champ every time I started it until it started acting up 20 minutes into the second cutting leading up to my post Sunday.

Two more things...
It may indeed be electrical because when I put the new VR in Saturday I used the screw from the old one, well it didn't hold it secure enough and when the tractor was running rough I saw the VR bouncing in the shroud opening and sparking a bit. I may have zapped something that was weak already.

The only other thing I can think of is the belt must have been too tight during the cutting cuz I could smell rubber burning. I didn't recognize the tension gauge on the front. :fing20: However mowing for 15 minutes with a tight belt shouldn't do anything except be a good way to ruin the belt.

Sorry for the book length thread. :beatdeadh Hopefully sometime in the future this saga will show up in someone's search and be helpful to them too. I know I'm learning a ton.
 

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The Magnificent
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Don't mow until you get the belt problem figured out. If you are smelling burning rubber, the belt isn't just too tight, it's most likely misrouted.

Let us know how the electrical tests go.
 

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Discussion Starter #12
Up to this point in my life my scalp has done a good job of holding onto my hair, I feel this tractor may cause hair to fall out in large chunks.

Right after work I headed out and tried to start the tractor. Nothing. Ok, following suggestions I pull a plug, checked for and got spark. Same thing on the other side. Pulled the battery to get at some of the wiring to clean up the connections and headed in for dinner. I spoke to my friend about it. Based on what I've told him he suggests going straight for gas down the carb next and see if she'll run. So before putting the battery back in I cleaned the connections on the fuseable link and one set of connections on the coil that was easy to get at. Just before pouring some gas in the carb I paused to see if it would start with out it, it did and has run perfect ever since. Put all the covers and air filter and all that back on and it fired up again. Go figure!

I don't think I'm out of the woods as I found a few things that need replacing before cold weather sets in (plugs and wires for sure plus some fuel line.) But at least its running and sounds really good. If it was a loose connection that makes as much sense as a fuel problem. Under load the motor is going to draw more fuel and amps, a "clog" in either system is going to cause problems.

Assuming I'm ready to cut again, what is the correct belt routing? Right now I loop over the PTO pulley, down through the idler pulleys and back around the deck (50" deck) pulley.

Thank you D-Dogg and the rest for all your help. I'm a lot more informed about my tractor and more confident in troubleshooting it than I was 3 days ago.
 

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The Magnificent
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If this has you pulling out your hair, go back and read some of the posts from guys with brand new rigs!

It's pretty easy to get one of the spring arms in the mule drive under the belt instead of over it where it belongs (voice of experience here). Also just verify your deck belt routing. Smelling burning rubber scares me.

Glad to hear it's running good. Electrical problems can really haunt you.

Enjoy!
 

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Discussion Starter #14
Just wanted to close the loop on this one. After a complete no-start (no dash lights or any kind of engagement) this weekend (following a tractor washing) I pulled and cleaned the key switch. It was completely green with corrosion so I took the wire brush after it and cleaned it all up as well as the terminals on the wires. Viola!

In the end and for future searchers I think my problems were all poor electrical connections that just couldn't sustain higher current flow or hold connection during the vibrations of mowing.

Thanks again all.
 
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