Onan P218G won’t start

[JaysHorse 287]

Ok so I ran this about a month ago. I went today to fire it up and put my blower on and won’t even fire. I even tried a little fuel dumped down the carb. Pulled both plugs and I have spark. Pulled flywheel and clean all that off too. I am getting fuel. Kind of stumped on this one. And ideas? This is on my 518H. 

Edited December 5, 2021 by JaysHorse

[WheelHorse520H 708]

Is your carb adjusted correctly? I know from experience that they are sensitive. What tractor is it on? I know this is a silly question but did you use the choke? I found my 520 starts best with the choke all the way up and as I crank it I lower it until it catches. Is the fuel new or is it stale?

[lynnmor 7,309]

If you put a small amount of fuel down the carburetor and you have new spark plugs sparking, then you should have at least some putts when you crank it.  You need to crank it immediately after pouring in the fuel.  I said new spark plugs because fouled ones may not spark under compression.

 

My Onans need full choke till they fire, then the choke needs to come off immediately, followed by a quick jab on if the engine falters.  All my Onans work like this, always did.

Edited December 5, 2021 by lynnmor

[JaysHorse 287]

1 hour ago, WheelHorse520H said:

Is your carb adjusted correctly? I know from experience that they are sensitive. What tractor is it on? I know this is a silly question but did you use the choke? I found my 520 starts best with the choke all the way up and as I crank it I lower it until it catches. Is the fuel new or is it stale?

The carb adjustments never been touched and have never had an issue. I always needed full choke until she fired up. 
 

you kidding me??? Of course it’s new gas. Onans never let the gas get old. Lol

[JaysHorse 287]

Well I guess a place to start would be some new plugs. 

[WheelHorse520H 708]

 

4 minutes ago, JaysHorse said:

you kidding me??? Of course it’s new gas. Onans never let the gas get old. Lol

Just have to make sure lol. New plugs might be it.

[JaysHorse 287]

So I had a thought. I also have a 416-8 with the Onan. I was thinking of robbing parts off that to try before I break the bank buying the wrongs parts. The plugs and coil should be interchangeable I think between the P216 and the P218 correct?

[RED-Z06 2,221]

2 hours ago, JaysHorse said:

So I had a thought. I also have a 416-8 with the Onan. I was thinking of robbing parts off that to try before I break the bank buying the wrongs parts. The plugs and coil should be interchangeable I think between the P216 and the P218 correct?

Yes.

 

Also remember that these Performer series hadca weird crank trigger setup that uses a special flywheel key to engage the trigger wheel behind the flywheel which signals the hall effect pickup to tell the coil to spark.  If they timing wheel isn't in time it will spark but out of time

[lynnmor 7,309]

4 hours ago, RED-Z06 said:

 

Also remember that these Performer series had a weird crank trigger setup that uses a special flywheel key to engage the trigger wheel behind the flywheel which signals the hall effect pickup to tell the coil to spark.  If they timing wheel isn't in time it will spark but out of time

 

 

He did say in post #1 that the flywheel was pulled, you may be on to something.

[JaysHorse 287]

I did not know that and I did clean some debris off that. Wonder if something got messed up. Guess I will grind my teeth and pull that shroud off again. Grrrrrr

[RED-Z06 2,221]

When i had a 316 deere i pulled the wheel and put the plastic back wrong..or the key wrong...it was way out of time.  Ran about 40 seconds...looked down and both pipes were cherry red...fun

[JaysHorse 287]

Not for nothing but for some reason I want to say the last time I used it it sputtered for a second and then seemed fine after that when I parked it. When I say sputtered it was almost like it shut down and then fired again. 

[lynnmor 7,309]

Page 8-2 in the Onan Service Manual will show you how to check timing.  It might save you from pulling the flywheel unnecessarily.

[JaysHorse 287]

Figured since I’m waiting for plug wires I may as well take heads off and decarbon them since I bought the gaskets over a year ago. 

[JaysHorse 287]

I did pull off flywheel and check they woodruff key and the plastic ring and all look good and now clean. Got some new plugs and just waiting on new plug wires. I also verified all resistance on coil and everything checks out to manual specs. Snow is here so something’s got to give here. 

[lynnmor 7,309]

Did you check the valve seats when the heads were off?  Did you check the compression?

[JaysHorse 287]

5 hours ago, lynnmor said:

Did you check the valve seats when the heads were off?  Did you check the compression?

Haven’t pulled the heads yet. Hopefully tonight. As far as compression I use a rigged up homemade jobber. Seemed good up around 110 area if I remember correctly 

[Bill D 1,926]

Take a jumper and go from the positive terminal on the battery to the positive terminal on the coil.  If it fires up, check the 9 pin connector.  I'm thinking electrical problem.

 

[kpinnc 12,111]

20 hours ago, Bill D said:

Take a jumper and go from the positive terminal on the battery to the positive terminal on the coil.  If it fires up, check the 9 pin connector.  I'm thinking electrical problem.

 

Bill has a good point here. Bypass everything and see what happens.

 

You've covered the basics of the engine electrical itself. Might be a good time to check the tractor. 500 series have quite a bit of wiring and safety switches. The last time my 520 acted up, the culprit was a worn out key switch. Time before that was a coil that was going bad. 

[Lee1977 6,673]

On 12/12/2021 at 9:48 AM, kpinnc said:

 

Bill has a good point here. Bypass everything and see what happens.

 

You've covered the basics of the engine electrical itself. Might be a good time to check the tractor. 500 series have quite a bit of wiring and safety switches. The last time my 520 acted up, the culprit was a worn out key switch. Time before that was a coil that was going bad. 

I had to replace the key switch on my 89 when I got it. Also pulled the red power wire and starting wire out of the 9 pin connector. Soldered those wires together, I have a couple of better connectors for a rewire but It's working good now

so I haven't used the new connectors.The two safety switches on the PTO lever and the one on the motion control can cause problems, The two PTO switches have plastic insulators between them mine were covered in rust, my guess is they were  grounding out.

[JaysHorse 287]

Well after a lot of testing I found the problem is the ignition switch. Should have a new one at my doorstep come Thursday. 

[JaysHorse 287]

Ok now I’m stumped again. So with the old ignition switch I could get it to fire if I fiddled around with it. Installed new switch and still nothing. What am I missing?

[JaysHorse 287]

I find it hard to believe it’s one of the safety switches because I believe those would prevent it from turning over all together. Or is that not right?

[RED-Z06 2,221]

Are the terminals labeled the same? B,G,L,M...etc?

[Handy Don 12,237]

25 minutes ago, JaysHorse said:

I find it hard to believe it’s one of the safety switches because I believe those would prevent it from turning over all together. Or is that not right?

Have you pull the OM and wiring diagram from the files section for your tractor? Read through it and you'll get a clear explanation of how the safety switches govern starting and running. The 518-H has a good bit of wiring so the problem could be in a lot of different places.

 

27 minutes ago, RED-Z06 said:

Are the terminals labeled the same? B,G,L,M...etc?

Agree with this as a starting point! And are the wires all connected to same-lettered terminals on the new switch as the old switch?