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Discussion Starter #1
Hi!

I purchased a 1988 John Deere 316 with a snow plow and mower deck last Summer from the school district that I work at. The mower had sat for about two years prior to being sold at auction. I paid $100 for it. The mower was used to push snow there as recent as 3 years ago. So I know it ran when they put it up. I replaced the battery as it was not getting any juice at all and it was rather old. I also had to replace the rear tires as they were dry rotted and flat. When I last messed with it last Summer, it cranked but would not start. I left it out all last summer and through the winter.

Fast forward to yesterday... I pulled the old mower back to the shop yesterday and started to do a little bit of digging into the issue. The mower did not crank at all. The mower has an Onan P218G engine in it. When I turn the key I get the oil pressure light and the battery light flashes and goes off. When I go to crank it over I get nothing. I checked the seat sensor switch on the back of the mower and found that it had been jumped with a piece of wire. I checked continuity on the wire and had positive continuity. I checked the PTO switch and when I turn it to the on position I do get lights on the dashboard. I checked the position of the hydrostatic lever and it is in the neutral position. I also replaced the negative end on the battery terminal wire.

I decided to check the ignition system further and could not locate the starter solenoid. (I did read on the forum that the solenoid is attached to the starter and can only be replaced with the engine pulled.) I found the ignition coil and checked voltage at the coil. I have power at the positive post when I turned the key to the run position and when I turned it to start. I'm assuming that the ignition coil does not get voltage until the safety switches are all satisfied?

Are their any easy ways to check the ignition system without pulling the engine? If so what is the proper path to troubleshoot?

Thanks for the advice!


Cheers,

Joe :greentractorride:

IMG_20190608_163459.jpg

IMG_20190608_194915.jpg
 

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Joe,

:wgtt:

The best way to diagnose the 316 with Onan P48 engine is to use the methods described in the Technical manual (TM1590.) Attached is a low resolution version you can use until you purchase a full version:

View attachment 318 Tm1590 reduced filesize.pdf

The P-series engines do have the solenoid mounted to the starter low on the engine by the frame rail -- but you can still see the terminals of the starter if you look closely...see the attached illustration (sorry for the poor image quality...).
starter improvement relay install 3.jpg

The solenoid is powered from the key switch through multiple safety interlock switches -- later model tractors have a parking brake interlock as well as the neutral switch and the PTO switches. see the below wiring excerpt:

318 Starting circuit.JPG

Let us know what you find and we can suggest further things to try.

Chuck
 

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Discussion Starter #3
Hi Chuckv!

Thanks for the reply! Well I finally got to do a bit more digging this morning. I have power all the way around from my 20 AMP circuit to the oil light, tractor lights, pto switch and the selinoid when the key is in the run position. It looks as though it's likely the selinoid.

How difficult is it to replace that without an engine stand? Do you have to completely pull the engine in order to replace that? Any advice folks can give is greatly appreciated!!

Thanks again for pointing me in the right direction. I believe that is the issue.

Cheers!


Joe :greentractorride:
 

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Just some advice from my car fixing experience.

Does the solenoid "clunk" when you turn the key to start? If not, I've been able to "temporarily" coax a solenoid to work by giving it a couple of light taps with the handle of a hammer. That is if you can reach it. From the diagram posted, the solenoid also advances the starter gear in addition to energizing the starter. Things get stiff when they sit and a "little" tap can get things moving.

Just my 2 cents.
 

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Discussion Starter #5
Found the problem! I found a stray hot lead that was not hooked up. Further examination of the starter / selinoid I found that the lead was not connected. I connected things up and we have ignition. ;-) Woo Whoo! Now time for some fresh fuel and start on the mower deck. Than maybe a restoration project later this summer.

Thanks for the inspiration. I almost took it to the mechanic.

Cheers! :bigbeer:


Joe :greentractorride:


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Discussion Starter #6
More Ignition Issues

Hi all,

Well, after I got this guy started, I ran into further ignition issues. Here's where I am... I checked spark at the plugs and we are getting good spark. I had noticed that the fuel line didn't have a great vacuum on it so I replaced the fuel line from the pump, the fuel filter and the remaining line to the carb. I also replaced the fuel line clamps with better screw type clamps. Now I get a great vacuum and plenty of fuel to the carb, but it will not start. The engine will crank like crazy but never fires over. I had initially thought that it was the battery so I tried jumping it and it didn't work either. I took the battery down to the parts house and they checked charge there and it was 82% charged. They even gave me a new one to try and it didn't work either.

After following the manual I noticed they recommend going over the carburetor. My local parts house doesn't deal with onan engines and doesn't have any cross referenced carb kits for me. I found the correct onan part number in another thread. My plan is to remove the carb, and rebuild it.

One other thing, I was told by the previous owner that they had to choke the heck out of it to get it going. I also noticed that this engine has the onan surge. I'm guessing a lot of that is the poorly maintained carb...

Do you have to remove the entire intake to remove the carb?

Any advice? Does that sound like the correct direction to go?

Thanks guys!


Cheers!


Joe :greentractorride:
 

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Because it sat for multiple periods of time, the carb is most likely the cause, if you have to choke it, check the low idle jet and emulsion tube (combination), there are also 3 small holes in the body of the carb, on the side where the welch plug is, make sure those are clean, use carb cleaner there, no wire because you may enlarge the holes and change the air fuel ratio. Was the surge at low RPM or even up towards WOT?
 

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Discussion Starter #9
Bloodrunsgreen,

I sprayed carb cleaner thoughout the carb. I have never attempted anything like this in the past and did not see your reply while I had things torn apart. I will have to look at adjusting the fuel air mix. I'm betting that may be the cause. Please watch that short video I linked. That may give more light on the issue. Thanks for the advice! I'll look at making the adjustments in the morning.

Cheers!


Joe :greentractorride:
 

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Discussion Starter #11
Bloodrunsgreen,

So I did find fuel under the float. I did remove and clean the idle jet. Is their anything in particular to look at with the idle jet?

Thanks!

Joe :greentractorride:
 

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If I recall correctly (IIRC), there are holes 3 or 4 (2 sets 180 degrees apart) that are across the tube and 1 in the bottom, they must be clean thoroughly (soak in carb cleaner over night). Also did you see the 3 tiny holes in the inner throat of the carb located across from the welch plug (just above idle set screw)? those need to be cleaned also.

After doing that, double check for spark (electronic ignition module, that fires the coil, make sure condensor is connected to the + side of coil and well grounded). Then it is down to having compression, so a compression check, finally a leak down test to check the valves.
 

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Blood; Condenser to + side of coil ????

Mount; Hold off connecting condenser until someone verifies...condenser to + or - side of coil. Bob
 

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For the P-series engine, the condenser goes to the plus side of coil (for a B-series it goes to the minus side...) Here is the wiring diagram with the P-series info and the B-series in the drawing insert...

ignition diagram 318.JPG

Chuck
 

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Discussion Starter #15
So an update to this project.... I had a good friend of mine who is a mechanic look over things with me. We tried several things. I should have probably soaked the carb in parts cleaner before I threw in the towel but I'm pretty certain I have a couple of issues here. I ended up testing the fuel line going from the gas tank to the fuel pump. I hooked up a spare piece of fuel line from the pump directly into a can full of fresh fuel. The carburetor appeared to be getting fuel. I got a couple good back fires finally. The charge on the battery appeared to be weak noted by the lack cranking power from the starter. I left the battery overnight on a trickle charger and in the morning when I tested things my starter would not even crank. I would get a clicking sound only. I finally had enough and just called the local small engine guy to come pick it up. It's now sitting in his shop waiting for an estimate.

I'll post what we finally figure out. I"m not giving up on the old girl. It's a great lawn mower and I sure don't want to buy a new expensive piece of plastic to mow with.

Thank you all for the help and suggestions! I know just enough to be dangerous and without an engine jack or pulley and the time to do things right, I'm better off sending her to someone who can do it the right way.


Cheers :bigbeer:,

Joe :greentractorride:
 

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I have a 1987 316 with the 218p onan and the previous owner said that it took a long time to pick up gas from the tank and doing the same thing as you are doing, choking it during the whole process. I replaced all the fuel lines from the carburetor to the pickup tube in the tank. I installed a check valve filter on the pickup tube and a put a inline check valve right in front of the gas tank. If I crank it once a week then fires right up but if it's been two or more weeks since I have cranked it then it takes just a few more turn overs with full choke before it fires off. If you have not checked , the pickup tube may have broke off or stopped up. Good luck
 

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Forgot to mention that while I had everything tore down I pulled the gas tank off and flushed it out, you would be surprised to see what came out after 32 years. I also replaced the two rubber grommets where the fuel lines enter the tank.
 

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I have a 1987 316 with the 218p onan and the previous owner said that it took a long time to pick up gas from the tank and doing the same thing as you are doing, choking it during the whole process. I replaced all the fuel lines from the carburetor to the pickup tube in the tank. I installed a check valve filter on the pickup tube and a put a inline check valve right in front of the gas tank. If I crank it once a week then fires right up but if it's been two or more weeks since I have cranked it then it takes just a few more turn overs with full choke before it fires off. If you have not checked , the pickup tube may have broke off or stopped up. Good luck
Ronbuff, I just sold my '87 316 with the P218G. I changed out the same parts quite awhile ago. Always the same results. A few days to a week sitting, and it fired right up. Longer time between use, and I'd have to crank that thing 30 seconds or more!:unknown:
 

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Glc ,I didn't notice till after I had wrote a reply that it had been a couple of months since you posted. This is the first time I've been exposed to a 316 and I am having a great time messing around with it. I am retired now and it's my project, I couldn't find any decent impliments for it so I am building all of them. Well good luck with your next adventure. Have a good day .
 
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