Onan Gen Set 7500 Diesel

[Ccoddou]

I was on my way back from a trip this weekend and i discovered that my Onan Gen Set 7500 will not start. I have a full charge on the battery and all breakers are good (solid on / solid off). Is there something I am missing. It is definitely something electrical because I get zero power. When I left for my trip, it was working. I never used it during the trip because of the cool temperatures. I turned it over when I reached my destination just to check and it worked fine. On my way back home, (at night) I tried to start it for lighting and....nothing. On another odd note, my fridge wouldn't even work on the LP gas setting. Is this because it requires voltage to switch it? Any help would be appreciated.

If it helps, I have a 96 Winnebago Vectra Grand Tour, Cummings Diesel, Allison Transmission and a Freightliner (Osh Kosh) Chassis.

[Big_Katuna]

But it will still crank.

[cbeierl]

The generator fuel intake in the fuel tank is placed at approximately the 1/4 tank level so that you can't run yourself out of fuel with the generator.

[Ccoddou]

sprinter293 wrote:
I have that same Generator and as a safety feature it will not run or start if the diesel fuel tank is under a quarter.

Hopefully it is something simple.

That was the first thing I thought of because my old class C had the same feature. However the tank was 2/3 full when it wouldn't start. When I finally got it started, the tank was showing less than 1/4 tank. Hopefully the gauge is inaccurate and mine has this same feature. I will run the tank low this weekend and see if it shuts down on its own.

[cbeierl]

Ccoddou wrote:
Well I managed to tinker long enough to get the generator to start. My best guess is that I hit a combination of switches and disabled it. Wish I knew how to do it on purpose to save my battery. What I did was press the AUX battery and AUX start buttons in conjunction with the generators start button and it fired up like a champ. I ran it for 5 minutes...turned it off for 5 minutes and it fired right up. I am even getting the backlight on the switch. Not sure I know what the problem was but I know the solution if I ever encounter it again. Thanks for the help

I think your AUX Battery switch is your house battery cutoff switch. The AUX Start switch should connect your house and chassis batteries together as long as the switch is held down.

[Ccoddou]

Well I managed to tinker long enough to get the generator to start. My best guess is that I hit a combination of switches and disabled it. Wish I knew how to do it on purpose to save my battery. What I did was press the AUX battery and AUX start buttons in conjunction with the generators start button and it fired up like a champ. I ran it for 5 minutes...turned it off for 5 minutes and it fired right up. I am even getting the backlight on the switch. Not sure I know what the problem was but I know the solution if I ever encounter it again. Thanks for the help

[sprinter293]

I have that same Generator and as a safety feature it will not run or start if the diesel fuel tank is under a quarter.

Hopefully it is something simple.

[FIRE_UP]

iamalienru wrote:
I have a 98 onan quiet it runs off the chassis battery. I was having intermitten starting from the start button inside the coach. On the back side of the gen it has 2 power cables coming into the gen. Mine were semi corroded causing the start problem. I would diconnect them and make sure they are nice and clean. Check and see what type of power in coming in to the gen.

This was going to be my input too. While you may have a solid 13V at your batteries, down stream you may have a "break down" of some sort. Maybe like jamalienru had, some corrosion on terminal, or connection point, a really bad ground, corrosion inside the cables etc. Since you've checked all the switches/fuses etc., then I'd maybe head on over to the "bad cable/connection/ground" side of the investigation to see where it leads you. Good luck and please post back what you find as the problem so that others may learn.
Scott

[Ccoddou]

cbeierl wrote:
According to the Front End Wiring Installation diagram for your coach (page 11 of the pdf) the Coach Battery Disconnect switch is the lowest of three switches on the left side of the instrument panel, below the Radio Power and Aux Start switches. If that switch has been turned off that would kill the 12V power to the coach.

I see the switch you are talking about but unfortunately my vectra does not have this switch. All of my switches are vertical on the left and right side of my instrument cluster. There are no pre-existing holes in that location that would indicate that there was ever a switch either. I sure wish it had a battery disconnect though. it would save a lot of future battery charges. Thanks for the input though.

[iamalienru]

I have a 98 onan quiet it runs off the chassis battery. I was having intermitten starting from the start button inside the coach. On the back side of the gen it has 2 power cables coming into the gen. Mine were semi corroded causing the start problem. I would diconnect them and make sure they are nice and clean. Check and see what type of power in coming in to the gen.

[cbeierl]

Btw, if you go here Winnebago Wiring Diagrams and select your coach year and model you'll see full wiring diagrams for your coach.

[cbeierl]

According to the Front End Wiring Installation diagram for your coach (page 11 of the pdf) the Coach Battery Disconnect switch is the lowest of three switches on the left side of the instrument panel, below the Radio Power and Aux Start switches. If that switch has been turned off that would kill the 12V power to the coach.

[Ccoddou]

Just checked all batteries and confirmed 13 vdc on all three. It really seems like I have inadvertently switched something off by mistake. I will continue looking. If anyone has a suggestion, please let me know. I will take any input at this point.

[Ccoddou]

cbeierl wrote:
Sounds like you might have the house 12V power inadvertently turned off. Don't know where the switch is on your coach--might be the dash or by the front door.

I've checked all breakers, switches and reset buttons throughout the coach multiple times. You never know though. I discover new things every day. I will look around more.

[Ccoddou]

mccsix wrote:
My "old" recollection about this gen is that there is a s/w and/or fuse underneath a plate on the top of the gen in front that can stop it from running. I think the plate has screws holding it on.
Give it a look might fix your problem

There is a box on my firewall with a run/stop switch, (2) on/off switches and a reset button. I will remove the cover, look inside and get back with you.