416-8 Onan Runs for 3 Minutes and Quits

[rmaynard 16,293]

On 11/13/2020 at 3:10 PM, RJ Hamner said:

This originally started with the engine surging with help from @Ed Kennell, @lynnmor and @Bill D The carb was cleaned,new intake and exhaust gaskets. 

 

Got everything back together and found that the fuel pump had bit the dust. 

 

With the new fuel pump installed it fired right up and ran for approx. 3 minutes then shut down.

 

 

 

Okay, I going to throw something out there. If I have read this whole thread correctly, it looks like everyone is concentrating on electrical. I go back to the quotes above and think that there is something of value in those last two lines. In order for any engine to run you need three things; spark, compression, and fuel. 

 

Are you sure that you are losing spark and not fuel?

 

You said that the engine was surging which means it was running, which also means that originally you didn't have a spark problem. Seem odd that after doing all the "fuel" things that you would now have an electrical issue.

 

[RJ Hamner 1,025]

3 hours ago, rmaynard said:

 

 

Okay, I going to throw something out there. If I have read this whole thread correctly, it looks like everyone is concentrating on electrical. I go back to the quotes above and think that there is something of value in those last two lines. In order for any engine to run you need three things; spark, compression, and fuel. 

 

Are you sure that you are losing spark and not fuel?

 

You said that the engine was surging which means it was running, which also means that originally you didn't have a spark problem. Seem odd that after doing all the "fuel" things that you would now have an electrical issue.

 

Bob

This tractor reminds me of a house we had in MA. 
It was built in the late 1860’s. Every time we started to fix or repair something we would find 3 or more other things that needed repair. 
It started with the surge problem and I went thru the carb then I lost spark. Did all the tests and the coil was bad. It was my decision to redo the wiring on the engine side. If you had seen the earlier thread when I was tearing it do for the rebuild you would have seen that this tractor had lead a hard life without much attention to regular maintained. And when it was put away after they bought a new mower it became a hotel for vermin with a taste for wiring insulation. Since the chance of finding a new wiring harness was in the same category as finding the lost city of Atlantis I went thru each wire that showed chew marks or wear and spliced in new wire and then tested for continuity (not the most fun I’ve ever had).
When the fuel pump went south I DID wonder if that hadn’t been the cause of the surging but.......it is what it is. 
Since I did buy the second one to be a donor I am now in the process of stripping it down for parts (too bad I bought it after all the work on the wiring harness, it actually looks in pretty good shape) 

I guess that I am not too surprised at all the problems encountered when you factor in the age, lack of care it had and the fact that this is the most complex tractor that I have (it sure ain’t a Kohler with a basic wiring diagram). I still can’t believe all the things that have to be removed just to remove the carburetor.

So....stay tuned. I just might win this battle after all. But just between you and me.... I think this thing might be possessed!

[RJ Hamner 1,025]

10 hours ago, lynnmor said:

 

Later models have a gasket like material behind the module, perhaps to reduce heat from the engine block.  Be sure to clean the often plugged up narrow space under the engine to allow air to cool the oil sump.

Guess I better order some. 
Thanks!

Bob

[Bill D 2,247]

If you don't care about the indicator lights, it would be pretty easy to make a new wiring harness for it.  I would keep one indicator light for low oil pressure.  An upper dash panel from a 310-8 with the low oil sensor would work nicely.  An Onan needs the same things as any K series Kohler, fuel, air, power to the coil, power to the starter solenoid.  I wish you were closer, I would gladly rewire it for you.  Could someone here draw a basic wiring diagram up?  I don't have an auto CAD program.  Bill

[RJ Hamner 1,025]

32 minutes ago, Bill D said:

If you don't care about the indicator lights, it would be pretty easy to make a new wiring harness for it.  I would keep one indicator light for low oil pressure.  An upper dash panel from a 310-8 with the low oil sensor would work nicely.  An Onan needs the same things as any K series Kohler, fuel, air, power to the coil, power to the starter solenoid.  I wish you were closer, I would gladly rewire it for you.  Could someone here draw a basic wiring diagram up?  I don't have an auto CAD program.  Bill

Sunday I brought the “dog ” tractor inside and started taking things apart to salvage usable parts. Was finishing up this evening and thought I would take a look at the wiring harness to see what shape it was in. I had some doubts at first because the 9 pin connector was wrapped up with....you guessed it...duct tape.  As I started working my way back things were actually looking pretty good so I started disconnecting and labeling connections. Finally got to the taillights and carefully removed the harness from the tractor. Blew off all the big chunks of crud and wiped everything done and the inspected the thing for any chew marks or abrasions. The end result was a big WOW  With the exception of the 9 pin connector it’s is in great shape. 
So for now the plan is to replace the ignition module (ordered a new insulator) and then pull out the current patched up harness and connect up the harness from the 91. I ordered another 8 hole Packard 56 set of male/female connectors and since I had rewired the engine side I’ll have a dang near new wiring on this thing. 
If this project has taught me anything it’s 1) if you do a thing enough times you’re bound to get it right. And 2) if you take things apart and then put them back together enough times you get really good it it. 
 

Bob

[Bill D 2,247]

Spend some extra and buy the good double crimp splices as well for any wiring projects.  Pink for the 16 ga wire, blue for the 14 ga wire and yellow for the 12-10 ga wire.  Double crimp terminals have an extra metal sleeve to provide strain relief for the insulation.  Amp and Tyco make them.  They can be expensive however.  I am fortunate to have a local place that sell them in small amounts.  Also, check for a burnt fuse holder on the fuse block. That can cause your ignition to drop out when it heats up.  Bill

[RJ Hamner 1,025]

Well I think the end of all the problems has arrived.  I finally got some time to install another ignition module and put everything back together.

Fired it up and it ran for the entire time while I put all the tools away and cleaned up the workshop.

The interesting thing that I found was the insulator for the module. The old one was literally baked on the the housing and I had to chisel it off. Probably not a lot of insulating property left

[Handy Don 14,061]

Way cool! Congrats on seeing it through and now hearing that nice Onan twin exhaust sound without interruption!