Onan 7.5 won't start

prpickett · 08-07-2010, 10:33 AM

I have an Onan Quiet Diesel 7.5kw generator (model 7.5 HDKAJ/11451D). It ran great over the 4th of July holiday, however when I tried to start it this week, it first started and immediately shut down. Tried this a couple of times before I got the manual. I then checked and had an 18 fault (glow plug). I verified that the fuse was good, and since the weather is 90+, I tried to start again. This time I only got a clicking sound for about 3-5 seconds and now I have fault code 21 (service required). This happened last Saturday. I got back from my trip today and tried again. Still only a clicking sound, but initially fault code 18 and then when I try to start again, fault code 21. I checked the battery voltage on the back of the gen and it was as 12.6 vdc. I also verified that the three fuses were good. I would appreciate any help or advice. Thanks,
Phil

Lug_Nut · 08-07-2010, 10:49 AM

Phil, Sounds like you have, or had two issues. The first non-statr was probably caused by air in the fuel line. This can be caused by operating the genset at or near a low tank condition. Once you get it turning over this can be righted by holding the stop for 30 seconds two or three times prior to cranking. The clicking only sounds like a ground issue. When in non-use the voltage will read good. Using a pair of jumper cables, ground the genset directly to a good spot on the frame.
Hopefully, that will do the trick.

Peter

prpickett · 08-07-2010, 11:01 AM

Peter,
I researched a little online, and I think the clicking is the fuel pump. Is it possible that I "burned out" something trying to start it earlier. I don't think that I am hearing a solenoid click since at least on my car that is a pretty loud click. Is there a way to check the solenoid and starter? I have the top cover off but don't really see either of these items. Thanks,
Phil

Lug_Nut · 08-07-2010, 11:54 AM

The solenoid clicking may be much quieter than that of your car due to the insulation in the enclosure. Ground can be an issue on the slide out models. The only thing you can burn out by over operating is the starter motor.

Peter

Road Hawg · 08-08-2010, 04:25 PM

Phil, since you already have the top cover off you might try this. I had a similar problem and it turned out to be a simple fix. Look in the rear driver's side area of the generator and you should see a black box with two flat leads coming out of the top. This is the governor actuator and tells the engine to increase or decrease rpms depending on the load. Make sure that the two wires are securely connected to the leads. Mine had apparently vibrated loose during my last trip as my generator quit about half way home. Same symptoms as yours. Nothing but clicks for a while and then nothing but a fault code.
Hope this helps.

prpickett · 08-08-2010, 05:36 PM

I actually put the cover back on so I could go camping. Just got back. Will take it apart tomorrow and look. Tried the jumper cable ground and no change, just clicks (about 5) and then nada. I'll post tomorrow after getting the cover back off. I appreciate any and all ideas at this point.Thanks,
Phil

**RJay** · 08-08-2010, 05:56 PM

Are you able to start the generator while plugged into shore power?

prpickett · 08-08-2010, 06:41 PM

Nope, doesn't work with shore power, battery only, or with RV engine running.

**RJay** · 08-08-2010, 07:04 PM

It's important to determine the origin of the clicking sound you hear. Usually a clicking sound when starting is associated with either a bad solenoid or weak batteries that cause the solenoid to chatter. Once we get your generator running then we can work on why it won't stay running.

prpickett · 08-09-2010, 07:22 PM

Summary of findings so far:
1. Removed cover, leads are securely attached to the black box.
2. Used jumper cable to verify good ground, no change.
3. The clicking sound goes for about 5 seconds when I try to start. This is the exact same sound that I hear (with cover off) when I hold the button in the stop position, leading me to believe that it is the fuel pump.
4. I get the same response whether shore power is connected or just on battery. It also doesn't make a difference whether I have the battery on or off using the use/store button. I have verified battery voltage (12.8v) and the batteries are less than 6 months old.

When I initially tried to start the engine it did start very briefly at least a few times before it just started clicking. Each time it would either start or turn over at least but immediately shut down.

Is there a way to verify the starter solenoid or motor and does anyone know where they would be located on this particular unit? I welcome any other troubleshooting ideas.

**"007"** · 08-09-2010, 08:10 PM

You do have a full tank of fuel correct? I have a Generac and when I tried to start without checking fuel level, would hit prime switch and fuel pump did click and start Gen. But it stopped so primed it again and just got the clicking pump. The clicking would run for quite some time thought it was going to be new pump in the works.
So I dropped trying to start. Went camping filled tank and had near full tank on return.
Thought I'd try to start Gen again and run AC's for couple hours. Primed and just got clicking kept trying and all of a sudden the Gen started and I stopped it and tried again and started right up.
Just thought I'd ask if full fuel tank. The fuel pickup only drops 3/4 down into tank and your fuel gage may read over 1/4 but may not be enough for Gen pick up hose.

**RJay** · 08-09-2010, 09:10 PM

prpickett,
If the clicking your hearing is the fuel pump that means the starter isn't even tuning over so it seems to be losing battery power to the solenoid. Check the battery connection to the solenoid for 12 volts and that it's clean and tight. Where the generator started briefly it sounds like an intermittent connection problem.