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Jess

518H 18HP Onan

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People on here told me to use the Harley coil which was around $40 and the new Onan was around $175 and they told me it would do the exact same thing ? It is in some where in my original post when I first started to communicate  with helpers on this sight ! I don't know how to go back and look at my old post ?  I was also just reading that the trigger ring should have been replaced when I changed out the ing module . I did not know that at the time as I am new to this. When I changed the stator yesterday I looked at the BLK plastic ring and I saw no issues

so I just put the flywheel back on and assembled the machine . Do you know where I could buy one of these? and what does it do other then a spacer ?

                           Thank you for you input

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1 hour ago, Jess said:

If I just run a jumper from the Bat pos to the coil pos would that do the same thing ?

It may make it run.

The 3 steps I posted would isolate the problem to the 9-pin connector if it is at fault.

 

Garry

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  I just pulled the volt meter and it is defective . can I still run the jumper from the seat switch (Yellow wire ) to the positive on coil or do I need to put this back in for the next step ?

   Thank you for your time

      Jesse

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1 hour ago, Jess said:

  I just pulled the volt meter and it is defective . can I still run the jumper from the seat switch (Yellow wire ) to the positive on coil or do I need to put this back in for the next step ?

   Thank you for your time

      Jesse

Connecting to the voltmeter was just so you could monitor power to the coil while operating it.

 

Go ahead and try the yellow wire. Nothing to lose.

 

Garry

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Do I need to have the seat switch in place or just pull the wires off and hook to the yellow one ?

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17 minutes ago, Jess said:

Do I need to have the seat switch in place or just pull the wires off and hook to the yellow one ?

The seat switch powers the ignition when the pto is ON so the switch needs to be connected to the wires.

 

Garry

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 I was reading in another reply today about this ignition module I had replaced but I did not know about replacing the Ignition  Rotor / Trigger . Could this be a problem that I'm having ? I looked at it yesterday when I swapped out the stator but didn't know anything about it . It looked good as far as looks go. What does it do ? Should I order a new one as well ?

          Thank You

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I ran the jumper from the positive side of the coil to the yellow wire on the seat switch . There was no change . I ran it and mowed for around 20 minuets before it started to break up. This time I drove it back into the garage and just let it sit there and idle , if you can call it that (HA)  ran like crap !!!!!!  breaking up backfiring , If I gave it more throttle it would smooth out a bit , but when I idle it down it starts doing the same thing . Even when its revved up it still not smooth . But like it always does it runs great for the first 20 min.  I shut it off after the 2 hrs. and it even started up again . Just running lousy .
  So I left it run and it did not quit this time . as it was running I took the jumper off the seat switch to see if any changes , still ran the same . I left it sit there and run for 2hrs !  at least it ran and didn’t loose voltage . Could there be something wrong internally in the engine ? That when it heats up it causes it to do this?  Could it still be an electrical issue ? Would that trigger/rotor  ring cause this ? Like I said when I changed the stator the other day I took if off an looked at it and it appeared to be good . No wear or cracks in the plastic . I checked the voltage to the coil from the battery several times while it was running and was getting around 14 volts to the positive side. I put my meter across the 2 terminals on the coil while it was running and was getting about 3 volts . Is this what it should be doing ?
   At least I can mow with it 20 minuets at a time .
             Thank you

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Does it "backfire" out the muffler or thru the air filter?

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I had the air filter off as I have been doing so much work on it , it was backfiring through the carburetor ! I could see small flames at the bottom of the carb .

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Backfiring thru the carb is usually not an electrical problem ... that's a fuel problem.  what happens if you pull the choke out a little when it starts to backfire?   Or it's an intake valve.

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I’ve been dealing with so many electrical things just to get it back running is why I’m still lost on it. Pulling the choke out a bit doesn’t help at all. I hate to sound like a broken record but when I start it up cold it runs like a new machine for the first 20 min . It’s taken me 2 years off and on to get it to this point .
  The first 28 years I never had a problem with my machine. Then one day it just died and I had no spark and that’s when all the problems began.

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You fed the coil with the yellow wire so you now know it is not the 9-pin connector wire that feeds the coil.

 

Have heard some of these have a condenser on the (+) side of the coil. Do you have one of those and if so have you changed it? Have no idea how a failed one would affect the ignition being on the positive side.

 

Garry

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You've tried everything electrical and I think it's fuel related.    Try strapping a fuel tank to the hood and supply it with new fuel line.

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Just my:twocents-02cents: when my 97 520 would do exactly what you described run/mowing for 20 minutes +/-  then start dying then backfire and wouldn't restart till cooling down restart repeat ect...but would run ok/so so if not "worked" anyways getting to my suggestion (and I know you have replaced it) the ignition module, insulator, and trigger ring were replaced together has run like "new" ever since, so I agree with Cleat did you get a bad 1 and/or not replace the plastic/phenolic heatsink under the module which causes it to "fry" again...Jeff. 1st & 2cd pic the heatsink/insulator still attached to old module 3rd & 4th trigger ring really can't tell anything by looking at it...try Onan Parts.com or Boomer for these replacements...Cummins bought out Onan you're paying for the name and a discontinued production engine parts sorry.

IMAG2137.jpg

IMAG2136.jpg

IMAG2138.jpg

IMAG2139.jpg

Edited by WVHillbilly520H

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  I don't know if you can see some of my original post back in 14 but the condenser and coil were 2 of the first things I replaced , as far as the ignition module when I put the new one in no one had mentioned anything about the plastic Trigger Ring so I never changed it ? What do you mean by insulator ?  The plastic Trigger ring ?

I had never taken anything apart like this . I don't think I have a fuel issue ?  The fuel filter before the carburetor is always full and it ran for 2hrs today just very broken up and I had to add fuel to the tank to keep it running?  Could there be a problem with the fuel pump?

  When this started happening 2 years ago may tractor was never worked on (No Problems)  other then maintenance since the day I bought it home from the dealer .  It now has 1,300 hrs on it . 

   Would the trigger ring cause something like this to happen or maybe a valve engine problem ?

Edited by Jess
put

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Ok on my first and second pics there's a thin black disc that is just a bit bigger than the silver metal attaching bracket of the module, 1st from side/front 2cd back side where it actually mounts to the block this "disc" acts like a heatsink for the module, as far as the trigger ring when I had it done the 25 yr small engine Tech said its best to replace All 3 pcs at the same time for peace of mind as well all will be at a new starting/wear point...as for your fuel pump as long as your filter is full it "should" be fine as most run at half or less full but if it your filter hasn't been changed in a while a new 1 is cheap and usually bad pump gives you a surging/hunting issue under load while mowing ect ,not at idle, remove the pump screws and carefully pull the pump out far enough to get the clamp off the vacuum hose and remove and visually check hose for cracking,replace if bad, again be careful as it could fall in behind the air shroud tins this hose uses engine vacuum to operate fuel pump while cranking and running, another thing to check is the crankcase breather below the air filter housing with a hose coming up inside filter a little clamp holds metal fitting to the engine and inside is a "brillo steel wool pad" that gets all gummed up with oil over the years (should be info in the owners manual how to check/service this over looked part of preventive maintenance) use carb cleaner to clean and dry then replace, in picture below ,black hose 1/2" through next to red rubber spacer for air cleaner stud/nut all below filter housing next to intake manifold top of engine block ,Jeff.

IMAG2046.jpg

Edited by WVHillbilly520H

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I ha d the pump off and the shroud so I could pull the flywheel and change the stator the other day . That hose behind the metal shroud to the pump is a bummer to get back on. But it looked good .  I have never looked at the crankcase breather as I never saw it in my owners manual
I will check it tomorrow . If I can Ill take it all apart again and take the flywheel off and test the ignition module like member Old Iron had showed me back in 14 .  N3PUY had suggested it might be an intake valve ?
    Thank you for your time
   Jesse

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The valves and their  adjustment and or seat issue wouldn't have the the timed (20 minutes running and shut down and from my own experience leads me to believe it's the module/trigger ring combo), that would be more of a lack of power after warming up with a "rattling" sound while running and possibly "hunting" at W.O.T. like when mowing and the governor speeds the rpms up and down just slightly without increased load, and if the carb is dirty it wouldn't run right from start up ,revving up and down unless "choked" which is called surging which neither of those you have described and a stator is just basically the alternator which is controlled by the regulator and unless you were having charging issues wouldn't be causing the 20 minute shut down either, a bad/weak coil would just be a miss and lack of power or no spark/start as well as the condenser going out...and a bad voltage won't cause any issues it just shows charging state unlike bad amp meter which is part of the charging system as well as state of charge, just trying to cover all the bases,Jeff.

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IMAG2263.jpg

Edited by WVHillbilly520H
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Hi Jess, are you making any progress?

 

You've gotten a lot of good suggestions here.  As you may have observed, there are a lot potential solutions. And most are incorrect.

 

Your mission, if you choose to accept it, is the find the cure.  My advise is to list all of the possibilities.  Rank them from cheap and easy to expensive and hard.  Then work down the list and check each one out thoroughly.  Start at the cheap end. Don't throw any more money at this until you are sure you have found it.  

 

Be methodical and thorough and you will find it. 

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  One thing that I have not mentioned over all this going on the last couple of years is when I have the PTO engaged and am mowing it runs better ? When it starts breaking up and backfiring I engage the PTO and that will get it to calm down for a while , but then it still will go into its full breaking up mode , backfiring and surging !  I don't think it is the carburetor as it runs so well when it is first started . I will look at the ing module and trigger ring again. I hat to more money into another new ing module if the problem lies somewhere else .

                     thank you

       Jess

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  Morning Kurt-NEPA   ,  I don't know if there is a way to go back and see where this mess I'm in started back in 2014 , But this is how I started , new condenser, coil, key switch, starter solenoid , cleaning, cleaning, ext .  I put as many hors & days in it as I have had time for over the past 2 years . I worked strongly with a senior member OLD Iron  and others. It seems like I just keep doing the same things over and over again and end up in the same place . Maybe the motor just want to be put to rest .

                   Thank you for your time

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2 hours ago, Jess said:

  One thing that I have not mentioned over all this going on the last couple of years is when I have the PTO engaged and am mowing it runs better ? When it starts breaking up and backfiring I engage the PTO and that will get it to calm down for a while , but then it still will go into its full breaking up mode , backfiring and surging !  I don't think it is the carburetor as it runs so well when it is first started . I will look at the ing module and trigger ring again. I hat to more money into another new ing module if the problem lies somewhere else .

                     thank you

       Jess

So you are mowing PTO ENGAGED? Then 20 minutes in it starts breaking down running rough and then a backfire then nothing till it cools off and starts right back up... repeat?      This TRULY is the symptoms of a bad ignition module/trigger ring combo and if you didn't buy and install a new insulator when replacing the module the first time it ultimately led to the module going bad again, it doesn't come with the module you have to buy it separately sorry, now you do know you need that cheap little piece of insurance for the higher priced module and while your in there anyways new trigger ring too that way all is new at the same time,    then you say if you "disengage" (you have "engage" above twice) the PTO when it starts acting up it'll keep running but rough is because you took the load off the engine and the module/ring doesn't have to work as hard to keep the "sparks" going to the coil/plugs...I know I keep harping this combination but it the most common problem/fix with your described symptoms, I too fought this same thing throwing $ out for coil/condensor ect before throwing the towel and taking it to the small engine repair shop 7-8 years ago and he said this was the most common issue/fix, has been running like "new" ever since,Jeff.

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Yes Pto and mowing for 20min then it starts all over again . I called the only small engine shop in my area last year and he told me all he would do is start changing parts so that is why I took it on myself . The only Wheel Horse dealer here is around 60 miles away and when I called him for the price on the coil and ing module it was almost  $400 with out the labor , just the 2 parts !    I will try and get back at it later today and test the module .

      Thanks again for your help

      Jess

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jess

can you post a pic of the harley coil?

is it for a harley with point ignition,

or one with electronic ignition?

does it have designated primary posts

for + and -?

what is the S.N. of your engine?

the BLACK PLASTIC rotors are KNOWN to

have a weak/bad magnet located next to the

keyway.

thank you. boomer

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