Onan (Kubota) 7.5kw starts runs dies

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Onan (Kubota) 7.5kw starts runs dies

August 03, 2016, 12:28:49 pm

My Onan (Kubota) 7.5kw generator has started acting up on me. It starts up runs for 10 seconds or so and starts coughing and spitting and dies. I see the shutoff solenoid come on while starting then it starts to shutoff. If I hold the shutoff open to keep the engine running but it still sputters and dies.

In the spirit of easy things first I replaced the fuel filter since to me it looks like a fuel starvation issue. Unfortunately still does the same thing. I'm thinking fuel pump but am worried about the shutoff solenoid wanting to shutdown right after startup. Does the fuel shutoff solenoid shutdown in response to low fuel pressure?

I've found a fuel pump on ebay for $60 plus $14 shipping. Universal Electric Fuel Pump 3 5 3 1 2 PSI Lbs | eBay

What do you guys think? Attaching a pic that someone else posted that I downloaded for reference a while back. Sorry I don't know who posted it to give credit.

see ya
ken

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #1 – August 03, 2016, 01:15:11 pm

Not sure if your models are affected like ours were or if you have addressed this issue already but the first thought was your fuel lines.

I suppose a good test would be to disconnect the fuel line and run a longer hose into a container and see if the gen runs ok?

Low sulphur fuel hardens the rubber hoses

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #2 – August 03, 2016, 02:43:31 pm

Yep. Before replacing anything, run a hose from a 5 gallon can of diesel directly into the genset. If the fuel lines are cracked they suck air and it dies after 10 seconds.

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #3 – August 03, 2016, 04:49:49 pm

Quote from: kenhat – August 03, 2016, 12:28:49 pm

Does the fuel shutoff solenoid shutdown in response to low fuel pressure?

No, they don't need to monitor that. Shut downs are automatic with low fuel pressure.

The fuel pump, if you give it 12 volts (with generator shut down), will make a ticking sound like a clock.
How low is is the fuel tank? (above 1/4 tank?) Lower levels will make air leaks worse.

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #4 – August 03, 2016, 11:03:05 pm

I did have cracking at the very end of the fuel hose. The rest of the hose looks in "great" shape. I cut off about ¾" and reset it. Still runs & dies. Not saying the hose is not leaking but will check everything else before rehosing!

@John I don't hear any clicking from the fuel pump during preheat or during cranking. (cranking may be masking any clicking) I'll run a hot wire to the fuel pump tomorrow and see if I can hear anything. I'd really like for it to "just" be the fuel pump.

If I'm still not sure I'll get a gallon of diesel & some fuel line and try the by-pass.

Thanks for all the ideas! Will let you know how it goes.

see ya
ken

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #5 – August 04, 2016, 06:01:14 am

You may not have to replace the whole fuel line. They frequently fail where they kink at the rear of the generator compartment, so you may be able to splice in new line from there to get you by for a while.

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #6 – August 04, 2016, 03:21:43 pm

Ken,

Replacing that old worn out fuel pump is probably a good place to start. I tried to clean mine up and it worked okay for a week and then the problems started again. Slow starts, stumbling, rough running, and shutdowns. I replaced mine with a Facet Gold-Flo 4psi from Airplane Spruce # 477060E FACET GOLD-FLO INTERRUPTER TYPE PUMPS from Aircraft Spruce recommended by Dave M and that fixed it.

If I don't run it for a couple of weeks it will still develop air bubbles from the old line and I have to bleed it to get a good fuel flow. I hold a big plastic coffee cup under the bleed screw opening and hold the preheat switch on the generator down. You can hear the clicking of the pump and watch the fuel as it's being pumped. My old pump would click a little bit and then stop. It may take full cup before you can see a good strong flow with no bubbles. Just pour that back into the big tank. After that it should start and run unless you have another problem such as low oil or coolant.

I try to run mine at least once a week and I haven't had any problems. It runs much smoother with a new stronger fuel pump and diesel treatment in the big tank.

Jerry

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #7 – August 04, 2016, 11:05:48 pm

On my 10KW, I had a number of times a shut down while running. I replaced the original painted fuel lines on the unit, as the supply line was new already. Problem continued to show up occasionaly for the next year. Then the unit would start, run 10 seconds and shut down like I had turned it off. At the suggestion of MOT, I replace the control board. It started right up and has given no issues since the new board was installed. I hope your issues are not the control board, at $350. And my control board is mounted on the unit, not remotely as some models.

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #8 – August 05, 2016, 10:15:53 am

People in the past have mentioned that there is a second filter, a small inline one that's hard to see. I've never looked for it so can't confirm that it exists.

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #9 – September 09, 2016, 01:12:09 pm

Thought I'd update with new info.

Couldn't get into Cummins before leaving town. They recommended Spitzer Electric. Got in last Wednesday. Symptoms have changed a little bit. Now engine will not start and no smoke coming out the exhaust. Ray (Spitzer tech) cracked open one of the injector fuel lines and only saw a small amount of fuel come out while cranking. Said fuel should be spraying everywhere has to be a fuel problem. Suspects the injector pump. Suggested I take it to Central Motive Power (they specialize in diesel fuel systems) a couple of blocks away. Of course all their techs were in the field and couldn't get me in for 2 weeks. We leave for the Grandvention on the 12th so that wasn't going to work.

Mentioned we would be in Pueblo and service manager says they have a branch there! He calls and sets up an appointment for me on the 12th! Now hopefully they get me in AND get me fixed!

Oh and Gayland I looked for a second filter but nowhere to be found. The fuel line is exposed from the fuel pump all he way to the back wall so don't think mine has one.

More to follow...

see ya
ken

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #10 – September 12, 2016, 07:38:14 pm

Had the guys at Pueblo Diesel Injection take a look at my generator this morning. Told them the history and they started pulling the hard lines to the injectors and cranking the generator over with the same result. Barely any fuel coming out of the injector pump. They aren't setup to rebuild the injector pump so would have to send to the Denver and will take probably 2 weeks. They pulled the part number off the pump and checked and no replacements available anywhere. I asked them to pull the hard line off the fuel pump to be sure it wasn't defective even though it was new. When they ran it a lot of air came out. He bleed the system at the injector pump and the injectors hit the start button and it fired right up! Ran it for an hour under load without issue.

So it looks like the fuel pump was the solution. Jerry gets the gold star!

I'm pretty annoyed that guy from Spitzer didn't do a little more troubleshooting before sending me off to get an injector pump rebuild. I'm also pretty annoyed that I didn't think to bleed the fuel system. Duh... Didn't know you needed to bleed the system for an electric pump thought only needed to do that for a mechanical pump. The tech at PDI said that only a tiny bit of fuel is expelled with each firing cycle and takes a lot of cranking to get any air out of the system.

I'm just really really happy my gennie is working.

see ya
ken

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #11 – September 12, 2016, 10:39:24 pm

Ken,

Good new on the fuel pump. If the symptoms start up again just Let It Bleed!

Gregory Jones has an excellent DIY video on replacing the fuel line when your ready to take on that project. Pierce just recently replaced his and it's on my bucket list also.

Jerry

http://www.youtube.com/watch?v=DaFPB1O36N4

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Onan (Kubota) 7.5kw starts runs dies

August 03, 2016, 12:28:49 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #1 – August 03, 2016, 01:15:11 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #2 – August 03, 2016, 02:43:31 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #3 – August 03, 2016, 04:49:49 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #4 – August 03, 2016, 11:03:05 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #5 – August 04, 2016, 06:01:14 am

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #6 – August 04, 2016, 03:21:43 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #7 – August 04, 2016, 11:05:48 pm

Re: Onan (Kobota) 7.5kw starts runs dies

Reply #8 – August 05, 2016, 10:15:53 am

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #9 – September 09, 2016, 01:12:09 pm

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #10 – September 12, 2016, 07:38:14 pm

Re: Onan (Kubota) 7.5kw starts runs dies

Reply #11 – September 12, 2016, 10:39:24 pm

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