[sbkotcd]

Hello all,

I am new to this forum and fairly new to the world of small engine repair. Although I can do some minor tasks I don't have the experience that many of you do. I own a 1991 JD 318, which I've owned trouble free for the past 7 years. However, now I have an issue that I cannot seem to resolve. My Deere will not start! Battery is good, and it turns over just fine (it really wants to start!) Unfortunately it will not catch. I've replaced the plugs, tried some sea foam in the gas, (maybe it got some water in it?), tried some carb cleaner too, but the results are the same. While I'm trying to get it started it likes to backfire, loudly. I assume that means it is getting gas? What are some thoughts on what might be wrong? Any advice would be greatly appreciated, I need it to plow my 600 ft driveway.

 

[knottyrope]

back fire out of carb or exhaust?

if you use starting fluid, will it run for a few seconds after a good spray?

 

[sbkotcd]

Backfire out of exhaust. Can't even get it to run with the starting fluid. Just turns over...

 

[bo2009]

Could be any number of things.
Getting fuel? All switches OK? Carburetor & Coil OK? Ignition? Timing? Condensor/capacitor? Plugs, ALL wires, etc.. OK?
To begin: Do you have the Operators Manual for your 318? It has three pages of engine troubleshooting (although too many
solutions in that manual are: "See Your John Deere Dealer"). The Technical Manual contains many tests too.
Since it's run well for years, hang in there, you'll get help & figure it out & fix it. Bobo

 

[dhager4692]

Your description indicates it is getting gas. It also indicates the cranking system is doing its job. What is left is the ignition system. You should have the P218. I'll let others give advice on this engine as I have the B43G in my 318's. My thoughts are that a key is sheared causing the timing to be off which causes it to backfire. I think I have read about it one this site before.

You might try the search engine for "P218 backfires".

 

[7dad34]

Ok, first of all, stop using starting fluid ! Not good for anything at all. Do you have a good manual for your motor ? Check the plugs. How old is the gas ? If it's the older motor, points and condenser first, that will likely fix everything.

 

[dave_thompson]

Keith if the engine turns over hard and backfires it's more likely sheard flywheel key.If you pull flywheel to change key wipe crankshaft and flywheel mating surfaces with brake clean. If you put anti seize or oil on it it will shear again premature. Dave

 

[wmgeorge]

You need to start with the basics.

Could be bad gas, or water or dirt. The fuel pick up is at the bottom of the tank... and that is where the water and dirt or crud is. I'd drain the tank and put in fresh non ethanol gas with Sta Bil. I use Premium gas in seldom used equipment.
When you remove the plugs after a starting attempt are they wet with gas or dry?
Are Both plugs firing? Remove one at a time, let lay on the block so they are grounded. In a darkened area you should see spark.
No spark on either? Check points and ignition. Spark on only one? Could be spark plug wire or bad plug.
Good spark on both and fresh gas, both plugs wet with gas, then look at the shear key solution.

 

[shadetree]

Mr. George it's probably not picking up fuel from the bottom. If the selector is pointed back towards the fuel tank for the main line then it is using the all metal pickup that does not go to the bottom of the tank. If the selector is pointing away from the tank it is using the reserve line which chances are good that it has broken and no longer reaches the bottom of the tank. Should the reserve line be intact including the screen -- water and crud will not be picked up. The screen allows gas through but not water and only the very finest of crud.

 

[wmgeorge]

And we are assuming that both lines inside the tank are still on the connections and not laying on the bottom of the tank?

What IF that metal screen was plugged on the outside with dirt?

Fastest way to check is see if the plugs are wet, and they if they smell like gas.

 

[bo2009]

Keith,
It'd be sweet if a simpler fix like a carb. adjustment, fuel delivery change, replace a wire, valve work, etc. will get
you going again.
IF does turn out to be Ignition, Timing - Flywheel Key replacement - I suggest you replace the Ignition Module, the
Trigger Ring\Rotor & the capacitor too, and be sure ALL are installed correctly or you still may have problems.
Good Luck. Bobo

 

[dhager4692]

Also a compression check will tell you the condition of the cylinders. A known problem is the valve seats coming loose. If the compression is close between the cylinders, that eliminates that problem. And its a easy check.

 

[dd57chevy]

Mike , I have to disagree strongly with the comment on starting fluid . Not being mean , but I have my drive & 14 mi away my Mom & her elderly neighbor's drive's to clear . 1 tractor at ea location but only 1 heated garage . 1 of them wouldn't start ( yesterday >temp right at zero). Yep , the one w/out a heated garage .

It took 3 separate quick sprays & that thing was going . That $2.99 O'Reilly S/fluid saved me HOURS of transporting, diagnosing , etc .

Yea , I agree , if an IDIOT sprayed too much of the stuff down the carb throat it could be dangerous , but you can't fix stupid !

No offense intended .

 

[KB]

Dave,

I bet a warm jumper pack, or a jump from your truck would have got it going. No diagnosing or transporting needed. my 112 never started in the winter with the original L+G battery, I just hooked up a 100Amp charger on cold starts, and off I went. I have caught a snowmobile on fire before with starter fluid, because the sled backfired and lit the gas in the carb. luckly it was winter and there was snow everywhere to put it out

KB

 

[chuckv]

Back to the original poster's question:

First, Keith -- welcome to the WFM forum!

Have you noticed that the 'backfiring' only occurs when the ignition key is turned from START all the way to OFF? If that is the case your engine may be severely out of time, due to the magnetic rotor not being engaged with the extension of the crankshaft key. The P series engines have an electronic ignition module behind the stator (under the flywheel) so any inspection or replacement of the module and rotor would require pulling the engine.

Here is a WFM thread or two on this topic:
http://www.wfmachines.com/discus/messages/335/276259.html

http://www.wfmachines.com/discus/messages/335/82504.html

Quite often the module can become intermittent before any failure, so your symptoms are more indicative of the rotor being out of registration with its required position relative to the key slot in the crankshaft.

Let us know what you find.

Chuck

 

[wmgeorge]

So Chuck you think its a sheared key.

Need to be careful using starter fluid on a 2 cycle engine whatever goes into carb goes directly into the crankcase. Boom, more so than a 4 cycle which I have used on from time to time. for us folks in the North country its a necessity.

 

[chuckv]

Bill.

I had a P-series dealer transplant in a 317 that also acted like Keith's engine...the particulars were that it never fired while undergoing continuous cranking but would occasionally backfire as you were turning the key to off. Removing power from the electronic ignition module is similar to triggering it with the magnet, and if it were to occur at a better time than the out of position rotor -- then ignition spark would be generated at point just before the intake closed or just after the exhaust opened. The unspent fuel charge would be present from previously unfired cycles of the engine...

If when cranking continuously a rich mixture in the exhaust is smelled (unburned gas...) then there is no or insufficient spark to start/run the engine.

My crank/flywheel key on the Onan in the 317 was NOT sheared, but the rotor had been pushed off the rear of the extension and was way out of time. The flywheel was cracked and it was never determined if that was due to the "backfiring" which was pretty violent, or was part of the cause of the rotor being moved back out of engagement with the key extension. Here is the thread:
http://www.wfmachines.com/discus/messages/335/390507.html

Chuck

 

[7dad34]

Right. I am trying to figure where the idiot comment is coming from. I'm only conveying what I have read many times from many guys that know tons more than me. Do NOT use starter fluid.
That doesn't make me an expert or an idiot. It does however try to help someone to get their problem fixed correctly

 

[dhager4692]

Bill,

I agree with both your points about starting fluid. At times it is a necessity especially when the gas is not vaporizing as in very cold conditions as it helps the fuel to burn and warm things up.

But in a two cycle engine, if the problem is fuel not getting in the engine, then the starting fluid acts like brake cleaner washing any oil in the crankcase out leaving metal on metal, not good. The fuel mixture also contains two cycle oil meant to lubricate the internals of the engine.

In a four cycle engine there is oil in the crankcase that helps to dilute it and it eventually vaporizes and is burn as the crankcase ventilation system delivers it back to the carburetor to be burned.

The danger is using too much as it is very explosive.

 

[dd57chevy]

Mike , I wasn't calling you or anyone else here an idiot . I was thinking specifically of a guy I grew up with . Think Gomer Pyle with a bad attitude . He did everything the hard way . 15 pumps with a grease gun instead of 3 or 4 . Working under a car that was supported by CONCRETE BLOCKS . (Anyone reading this , PLEASE don't do that !)

He was trying to get a car started by pouring gas , from a MILK JUG , directly into a carb with someone else turning the ignition when the engine backfired & the jug exploded . 2nd & 3rd degree burns . THATS the idiot I was talking about ........the bad thing is he was a distant family member ......

The guy should not have been allowed to operate a TOOTHBRUSH without supervision .

Not sure why you thought I was talking about you . Sorry for the misunderstanding . Still can't understand why you say it is useless .... Or why I'm keeping this thread hijack going .

PS: What Douglas said is true . I give it as small a shot as I can (less than 1/2 second) when using it . Guys (like the guy I was talking about) who spray it 2 , 3 , 5 seconds might as well try dynamite .