[rosco611]

Hi guys. I have a 318 with the b43g. I have been having problems with it dying while I'm mowing. the first time I thought it was the coil had gone bad so I replaced it with another used one to see if it fixed it. well it did till I had mowed about half of my 2.5acre yard. Then it started sputtering and died. So aggravated I put it in the corner and used my old reliable 316 kohler. that was that for last year. over the winter I bought a brand new coil and point and condenser. after installing these I thought I had it whipped. I have mowed all spring with it my yard 3-4 times and my parents twice. Today it decides to died again in the same manner it has in the past. I figured while letting it and myself cool off I'd ask for some ideas on what is going on. I know the kohlers really well and always heard how good the 318 is. But now after spending $1200 rebuilding the engine and all this frustration I'm close to selling it. I have noticed all this has always happened when its 80deg or warmer. Surely I can mow when its warm out. the old k-series never give me these fits. lol
Ross

 

[ddogg]

So does it restart immediately, or must it cool down for an hour or so?

How is the charge on the battery? Is the alternator light on?

 

[jw332]

Hello
What you have is a case of vapor lock.
The next time you run it lift the hood when she starts running bad and you should see the motor pick back up.
If you have a see Thur fuel filter ,you can see that the fuel not really going on to the carb
I have the same trouble with mine as some of all that shielding is missing.
Also make sure the fuel line is not touching any Hydro lines too.
There was a lot of shielding on those 318 to keep only cooler air being pulled in.There can be missing or leaking areas.
I was running without out front sheet metal or hood and my 318 ran great.
Put all that stuff back on and BALM ! vapor lock.
I am sure someone will can tell you where all that foam and gasketting goes and the firewall pad too.
This is only when the temps get up over 85 or so here in Fla.So off came the side covers.
The junk that people can fuel is no help either.
Please note I always blow out the motor and tins and the whole machine when I am done for the day.
With some of the machines I have seen it is no wonder machines did not catch on fire !
Thanks JW

 

[rosco611]

Drake it does have to cool down. I went out and installed a spark tester and it fired right off. The battery light does not come on and it cranks like it should. This time when it started I went back to mowing and made it another 20mins and then it coughed once backfire out the exhaust and now it's dead. I have lost spark.

James. Once it does I try to restart it and it has no spark and will flood. I thought the same thing about vapor lock.

 

[ddogg]

Ross, that' something to go on.

Step one - you did put the condensor on the negative side of the coil and not the positive?

Next, while the tractor is in a non-starting condition, do you have 12 volts to the positive side of the coil?

Finally, let's measure primary and secondary resistance on that coil. Try to get a non-starting reading, and a starting condition reading. (you do need to remove coil wires to get a proper reading)

Oh, and really finally, recheck the point gap.

 

[rosco611]

Drake, I do have 12.7volts at the battery. With out spark I'm only getting 10.3 to the pos side of the coil. The neg side I can't get anything. I have not checked the resistance yet. I'm gonna let it set the night while I'm at work maybe it will start so I don't have to try and tow it in to the garage.

 

[ddogg]

Ross, do you have the tech manual for the tractor? I think your voltage drop is a large part of your problem.

Coils will overheat at low voltage.

 

[rosco611]

No I don't have the manual. I was thinking the same thing. I hope I haven't fried this coil. It had sat 45 min when I checked the voltage and the cool was still warm.

 

[ddogg]

Did you disconnect the negative coil wire when you tested the voltage? If the points just happened to be closed, that would cause a voltage drop on the coil primary + lead.

 

[rosco611]

I didn't unhook the neg wire but I did rotate the engine over thinking that the point could be closed. I'll get it in the garage tomorrow and double check every thing and go from there.

 

[Hammerdown-7]

Hello Ross
If your coil check's out to be fine I strongly suspect that the Condenser is your issue. These Onan coil's produce much wasted spark and it is not uncommon for them to take out the condenser's rather quickly. I was replacing Two per mowing season in my 1983 John Deere 318, which get's very frustrating and costly. Some times when they go out or quit working correctly they will Pit or Burn the Ignition Point's. If this is the case with yours I would suggest that you get a hold of David Kirk engines he makes an Ignition part called the Point's saver. It eliminates the condenser and they are reasonable @ $32.00 shipped to your door. I Placed one on my 318 a year and a half ago, and have not had any Ignition issues since. he claims by using his Point's saver that it will add thousand's of hours of life to your Ignition Points. I would suggest that you Place new point's and his Point's saver to end your Ignition issues. Mine start's faster. Run's Smoother and seems to have more power with the Point's saver in Place. Here is a Link to his web page where you can read about them and order one.Now, he offer's a dual cylinder Super coil which look's to me to be made by Accel and well as High performance Ignition wires. I elected to stay with my Onan Coil as they are very Powerful and am still Using Factory Onan wires on my engine and it perform's just fine. I hope this helps, Kurt


http://www.kirkengines.com/

 

[rosco611]

I've looked at those before Kurt. I walked out to where I died last night before I left for work. After it had sat for a couple hours and it fired right up. I put it up in the garage and while I had it running I had left my spark tested on it. While it was running I noticed that when it stumbled there was a miss in the spark. Not in any rhythm or pattern. I kinda suspect the condenser now myself. I'm thinking about putting a wire from the batter to the coil with a toggle switch. I think that would rule out anything besides the points coil and condenser. But I think I'm gonna order that points saver any how.
Ross

 

[volvo4fun]

Another possibility is a short to ground in the wire from the coil to the points.

When that wire gets pinched somewhere it might ground out when everything gets hot.

To find out take a multimeter and test between the negative terminal on the coil and ground. Do that after the engine dies.

 

[wmgeorge]

Simplest thing you can do right now is remove the covers to get your mowing done. Put on that Points saver kit and see if that helps.
If it starts and runs but dies when it gets hot my guess your wiring is fine.

Vapor lock can't be ruled out.

 

[rosco611]

Well guys I'm not sure what to think I thought I'd mow till it quit again and I mowed the other half parked it in the garage with out it dying. But I did mess with the wiring some before I put it away and I think I'm gonna replace the wire going to the points. I have replaced it once before but I must have not gotten it routed right. When I wiggled it I got it to stumble and the intermittent spark. Hopefully that's my problem. I will order the points saver too just because I don't feel it will hurt anything. Thanks for the help and I'll let everyone know if I get it fixed.

 

[Hammerdown-7]

Hello Ross
I would run a new wire to the Point's Box from the negative side of the Coil and order that David Kirk Point's Saver Moduel it will only be a matter of time before your Condenser Bite's the dust. Regards, Kurt

 

[rosco611]

That's the plan for this go around at least.

 

[Hammerdown-7]

Hello Ross
In your previous Post you mentioned running a wire from the coil to your Point's I assume eliminating the condenser ? I would not suggest that as it will Not take long to Burn up a set of Point's running an Onan without an Ignition condenser. Once you get the David Kirk Point's saver install a new set of Point's and set their gap $ 0.19" and forget about your Ignition issues they will be cured. I Placed my Point's saver against my fire wall and used two 1/4-20 Bolt's to bolt it down. It is sucked into my fresh fire wall insulation Mylar that kind of Pad's it well. They are very easy to hook up and you will see a Big difference in the way that it start's, Idles and run's once it is installed. Regards, Kurt

 

[gzec]

I have a b48g. It also has points. The wire that goes under/thru the points box has shorted out and caused all kinds of issues. Check your wire if you have it and replace or tape it up.

 

[rosco611]

Glenn, I feel like that is what's wrong. As soon as the weekend gets here I plan on replacing that wire.