Onan Aux Issue
 

Not sure if this has been asked before but I have an issue I was hoping somebody may have encountered and can help.
My Onan unit in my race trailer is an ONAN AUX, 6.5 RV GEN SET.
It started kinda missing here and there and would shut down after running for roughly an hour or slightly under. It would start back up and run fine for approx. the same time and repeat. Then the last shut off, it would start back up but the moment I release the start button it just shuts off.
Any help would be greatly appreciated. can either post here or my email is davidsumma@windstream.net

Thanks,
Davey Summa
SUMMA PERFORMANCE
724-336-2785 SHOP
724-601-0219 CELL

Re: Onan Aux Issue
 

Will it continue to run if you spray carb cleaner into the carb? Do you have 12 VDC at the fuel pump and carb solenoid valve?

Sean

Re: Onan Aux Issue
 

David I need the Model designation letters off the ID label to be able to look up the machine you have.

I have not seen many of those so I am not real familiar with them.

Is it a diesel? The models I am thinking of were diesels....

Re: Onan Aux Issue
 

The MODEL: 6.5NH-3CR/23001P
The SERIAL: L873306308

It is a gas unit. I installed a new FACET Gold pump. It is in a Gold Rush Trailer that has been in storage for some time prior to purchasing it. I did run a hot wire from the battery and it made no difference. Like I said it fires right up, but shuts down as soon as I let go of the start switch. { either switch...on the unit or at the wall panel}
Thanks, Davey

Re: Onan Aux Issue
 

Ok David that is an old gas unit..

Has points and condenser and a coil and all that has to be good.
The engine has a low oil pressure switch. That could be your problem. Some were 2 terminal and close with pressure. That completes the 12v power for the ignition. If it has a 2 wire switch you can jump it and see if it runs with it jumped out. The switch is mounted above the oil filter on most of the old flathead Onan engines...

The switch can be tested with an ohmmeter. Whatever it reads engine off......it should be the opposite running.

N/O = normally open.....and that should close running
N/C = normally closed...and that should open running

2 wire closes or opens across the 2 terminals
1 wire closes or opens to the switches body....which will be grounded at the engine when it is screwed in.

Re: Onan Aux Issue
 

I really appreciate the help as these generators are not my specialty. I will check as your saying...starting with changing over and doing away with points.....if you have that it would help me out also.
Davey

Re: Onan Aux Issue
 

David I work on newer machines primarily so we do not keep parts on the shelf for an older machine like that.

I would not worry about the points since that is not likely your problem.

Not sure if anyone even makes a kit to eliminate the points.

I did try to install one of those kits on an old BF but it did not work properly. Had to stay with the points.

You can jump a 12v+ wire to the coil+ terminal and see if it stays running.

That would pretty much tell you the ignition 12+ power is not being supplied after you let go of the start button.

These machines are not complicated by todays standards....

Re: Onan Aux Issue
 

hooked a jumper wire from the battery to the coil: Started right up and ran fine.....LOL....now what do I replace????

Re: Onan Aux Issue
 

Oil pressure switch....

Re: Onan Aux Issue
 

I installed a new oil pressure switch. Still doing the same. I have to unplug the oil pressure switch and run the hot wire to the coil for it to start and run.

? what might be my next step?

Davey

Re: Onan Aux Issue
 

I would leave the jumper to the coil and put an oil pressure gauge in place of the switch to see how much oil pressure you have while its running.
Dan

Re: Onan Aux Issue
 

Yes verify that you have oil pressure with a gauge. Onans rarely lose pressure but it is possible.

Re: Onan Aux Issue
 

I have seen issues with lite weight/synthetic oils in stationery engines and generators. The conditions these units run in, closed compartments limited air flow, long periods of use seem to really like a heavier oil. I prefer a high quality 20w50.

Re: Onan Aux Issue
 

Onan's Onamax oil is 15-40 and they recommend it for all their machines. It gets very thick after running for longer than it should in the newer machines. 150 hours or less is a recommended oil change interval. Older Onan's like this one had a very hd bottom end and oil pump. Pressure loss on one of those was not common and they had 30-40 lbs of oil pressure at 1800 rpm

Re: Onan Aux Issue
 

I run valvoline 10w-40 fully synthetic in it.

Re: Onan Aux Issue
 

I have seen this cause the problem. Although the fully synthetic oil does provide proper lube for the engine, by the time the low oil switch sees the pressure it doesn't like it and errs on the side of caution. I have had to do more than a few oil changes to prove this to boat owners that were trying to get better fuel economy out of their marine gensets. Easy enough to see if this may be your problem. Also a different low oil switch make like what it sees better than the one that is on it now.

Re: Onan Aux Issue
 

When I went to the local onan place the switch I asked for was 309-0322 even though the individual behind the counter seemed to think that another switch was the one I needed.
(She showed me that two were listed but my series should have the other)The only thing was the switch she thought I needed required a different plug end. It was also three times the price for some reason. The wiring on my unit showed no sign of ever being changed from original so I went with the one that matched my wiring end. I hate to spend more money on another switch if isn't really the problem...but I just may. I guess I could drain the brand new synthetic oil and put in 20w-50 petro based.

Re: Onan Aux Issue
 

Did you install a pressure gauge in place of the switch to verify the pressure is good?

Oil weight should really not be an issue here but the pressure needs to be confirmed as good with a mechanical gauge.

The proper switch is a must......but if the pressure is low it may be your problem.

Obviously lower weight oil will have an effect on pressure as will temperature. I seriously doubt the issue is the oil your using.

The parts manual shows a single terminal switch and it is mounted in a 90 degree fitting.

Part number is 309-0319 and is also shown in the price guide as a good number and list price is $12....

Yes your machine has a run relay and a resistor that is part of this circuit. The oil pressure switch closes to ground when pressure builds up. 30lbs is the proper minimum pressure.

I cannot cut and past the page on testing this control circuity for you from the Servcice Manual and don't have a paper copy to be able to print out...Those old machines used a lot of old type circuitry....and once you verify the pressure is good you can move on to the wiring and find the relay and resistor....

If it is one wire it can only do one thing.....close the wire to ground and open it to ground. That generally means it controls something else......a relay.....since it cannot directly supply the 12+ needed for the coil......

Re: Onan Aux Issue
 

I will check the pressure with a gauge this week. My oil pressure switch is the correct one then. 309-0322 replaced the 309-0309 and 309-0319.

I exposed the switch panel and it looks very simple. very small board and two relays.