Kubota Generator rough idle then quits

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Kubota Generator rough idle then quits

May 24, 2013, 05:44:47 pm

Monthly Generator run resulted in failure. Generator starts, very "chug a chug) rough idle for a few seconds then quits; after 2-3 automatic restarts, it quit trying and displayed an "over crank" red light. Tried again after a few minutes; same result, but this time it tripped the breaker on the electric outlet I was plugged into and I couldn't get the unit to start at all. Checked fuel filter, looks good; drained some fuel from the glass bowl. Reset the circuit breaker on the outlet; tried again, started-rough idle then quit. The coach started OK and idled fine. The house batteries are fully charged. Look forward to suggestions on what to try/check next.

Re: Kubota Generator rough idle then quits

Reply #1 – May 24, 2013, 06:27:10 pm

Fuel starvation due to failure of electric pump, clogged filter, air in the line or possibly bad glow plug. Suggest checking electric pump for output, checking or replacing spin on fuel filter and bleeding lines. Check glow plugs if that does not do the trick. If it does not run well, run a fuel line from a gallon container. If it runs OK, then the problem is with an air leaking into the supply line from tank. Check all hose clamps and condition of the hose. Best to use the fuel injection type small hose clamps instead of the stainless screw type. If checking glow plugs, do past post search for testing procedure.

If you have the little needle valve above the filter, tighten the nut so no air gets in and you still can turn the small "T" handle. Some have the fitting, some don't.

Pierce

Re: Kubota Generator rough idle then quits

Reply #2 – May 24, 2013, 07:42:54 pm

Replace the inline fuel filter just before the small electric pump and you may be fine. Yes there is a inline filter but it may not look like it. DAN

Re: Kubota Generator rough idle then quits

Reply #3 – May 24, 2013, 09:53:54 pm

Symptoms are similar to my experience during December/January trip. I replaced the small primary fuel filter on the Kubota -- fixed -- not. Bled air from the "big" fuel filter -- fixed -- not. Tightened some clamps on the fuel lined and bled air again -- fixed -- not. Took it to FOT. After they replaced all fuel lines for Kubota AND Cummins, both run well.

I saw no obviously failing fuel lines until they pulled the tank and some lines, and showed me all the cracks and dampness from barely seeping fuel.

Symptoms indicate the possibility of the issues described in previous posts: fuel starvation or air invading the fuel lines.

Re: Kubota Generator rough idle then quits

Reply #4 – May 24, 2013, 10:10:49 pm

NAPA has this filter. Only $2 to $3

best, paul

Quote

Replace the inline fuel filter just before the small electric pump and you may be fine. Yes there is a inline filter but it may not look like it. DAN

Re: Kubota Generator rough idle then quits

Reply #5 – May 25, 2013, 09:22:34 am

I have an Onan generator in my 1991 U300 that did the same thing after I ran the diesel tank down below the generator's pickup. I had just bought the coach and suspected I might have to weigh it and pay taxes based on the vehicle weight so I wanted all the tanks and cargo bays as empty as possible. After I filled the diesel tank up I cranked and cranked forever and it eventually got all the air out of the system and ran fine. You can look in the diesel tank with a flashlight and see how many inches of fuel you have left until it gets below the generator's fuel pickup, which of course is the higher one. It's about 1/8 of a tank from empty before the generator runs out of diesel... Maybe you didn't run the diesel level down too low on your coach but I thought I'd write this for the benefit of other readers.

Scott

PS, I didn't have to weigh my coach to register it in TX. I registered it in TN this year and saved a lot of money compared to registering in TX. I didn't have to weigh the coach in TN either. I also saved money on my insurance by registering in TN... but this is way off topic, sorry

Re: Kubota Generator rough idle then quits

Reply #6 – May 25, 2013, 09:39:29 am

Scott,

Off topic but good insight. We are allglad to see you happy again with your FT after your radiator repair challenges last year.

Keep posting!

Re: Kubota Generator rough idle then quits

Reply #7 – May 25, 2013, 11:06:43 am

Scott Cook's post reminded me that I too recently ran my main tank low and required replacement of the glass bowl filter among other headaches. Maybe the likely suspect here.
I will check the primary (glass bowl) and secondary (spin on) fuel filter for contamination and will follow up with a post. Thanks to all for your prompt replies.

BTW is there also an inline filter somewhere? I did not see any on first inspection.

Re: Kubota Generator rough idle then quits

Reply #8 – May 25, 2013, 02:16:21 pm

Pictures of the 1997 Kubota filters are here: Powertech Generator Fuel Filter. Yours are probably different.

Re: Kubota Generator rough idle then quits

Reply #9 – May 25, 2013, 02:31:07 pm

Quote from: Fiddler – May 25, 2013, 11:06:43 am

Scott Cook's post reminded me that I too recently ran my main tank low and required replacement of the glass bowl filter among other headaches. Maybe the likely suspect here.
I will check the primary (glass bowl) and secondary (spin on) fuel filter for contamination and will follow up with a post. Thanks to all for your prompt replies.

BTW is there also an inline filter somewhere? I did not see any on first inspection.

Anytime the engine fuel filters have been changed because of suspected algae clogging, the generator filter(s) should be also changed. The generator may have picked up a bit of algae before the engine filter clogged. Cheap insurance to make sure all the bad stuff is gone.

Pierce

Re: Kubota Generator rough idle then quits

Reply #10 – May 25, 2013, 03:39:04 pm

a new generator filter solved those same problems for me.

Bill Schlaudecker
2000 U270 36

Re: Kubota Generator rough idle then quits

Reply #11 – May 25, 2013, 05:43:21 pm

There was one other time when I ran the diesel level down below the generator's pickup but I didn't attempt to start the generator until after I refilled the tank, so there wasn't any problem with the generator that time... so don't start your generator if you're low on diesel and you might avoid these issues... and if you think the diesel may be too low for the generator look at the generator's pickup in the tank with a flashlight before you start the generator.

Re: Kubota Generator rough idle then quits

Reply #12 – May 26, 2013, 05:02:17 pm

Coach has 2 generator diesel filters; 1 Racor primary behind the entry step well and 1 Fleetguard secondary (spin on) in the generator engine compartment. Today I replaced both (filled them to the top with diesel fuel); then the Generator started as normal with idle rpms OK; then it quits after 10-20 seconds. Removed the spin on filter and it was only half full now. Left the filter off and restarted gen and the electric fuel pump was pumping fuel OK (into a bucket). Refilled and reinstalled the spin on filter; restarted the gen with a repeat of the same result; starts, normal rpm, then quits. Checked the air filter, it's OK. The engine behaves like its getting fuel albeit for a short time......what's causing it to quit? HELP

Not sure if its part of the symptoms, but the GFS shore power outlet that I'm plugged into tripped a couple of times while I was testing the generator.

Re: Kubota Generator rough idle then quits

Reply #13 – May 26, 2013, 05:42:13 pm

Fiddler, not a good idea to run genny while attached to shore power, hard on contacts in the transfer switch box.
Try running genny on outside fuel source, get a can, attach direct to fuel line, if it runs alright you have a fuel line collapsing or leaking between the tank and genny.
Also, open the control box and check and tighten all wire fittings, I had a ring fitting break off and made momentary contact.
Gary B

Re: Kubota Generator rough idle then quits

Reply #14 – May 26, 2013, 05:57:38 pm

The symptoms are consistent with air getting into the fuel supply line. Gary's suggestion of running from a short, good fuel line supplied from an independent container seems line a good test.

After our genny started faltering, it might run as long as an hour before stalling. I could bleed the air from the spin on filter and it would start fine, but stall after a while.

Re: Kubota Generator rough idle then quits

Reply #15 – May 27, 2013, 09:41:47 pm

Took the advice here and fed the input fuel line to the electric motor directly from a gallon container of Diesel and it ran fine.
Reconnected the line from the tank and the gen quit once again.

Inspected the fuel lines and found the input and output line fittings from the Racor filter had a series of vertical 1/4" minor surface cracks right where the lines are press fitted just above the threaded connector. They did not appear deep enough to leak any air; however I will try to wrap both with a sealing tape and see what resultsl.

Re: Kubota Generator rough idle then quits

Reply #16 – May 28, 2013, 08:10:57 am

Fiddler, Bite the bullet and replace the line, if you don't now you will later. I know its a b... of a job but putting it off will not make it any easier.

Gary B

Re: Kubota Generator rough idle then quits UPDATE

Reply #17 – June 02, 2013, 08:34:20 pm

Tested all fuel lines beginning at the motor and worked backwards to the input of the electric pump. When I connect an external fuel source directly to the input of the electric pump, all operates perfectly. When I reconnect the pump to the main tank fuel line (coming from the racor filter) after topping off the spin on filter, it runs for 30 seconds or so and quits; consistently ~30 seconds.

Problem (most likely air intrusion as most of you suspected) lies somewhere between the input line of the electric pump back to the main tank. Checked as much as I could and didn't see anything except a few hairline cracks around the racor connector fittings. Wrapped industrial sealing tape around both connectors where the cracks were obvious but it did no good whatsoever.

The local Powertech service tech recommended bypassing around the racor filter assembly to eliminate it as a potential problem source. Unaware how to determine the male to male connector fitting sizes that I need to screw the input and output racor lines together. It's pretty hard working under there without a lift and I'm trying to avoid removing the racor altogether to determine the fitting sizes by trial and error. Anyone happen to have this information?

Re: Kubota Generator rough idle then quits

Reply #18 – June 02, 2013, 09:13:08 pm

Mine are 5/16 or 3/8, I forgot, be sure to use new clamps, I doubt the Racor is the issue.

Re: Kubota Generator rough idle then quits

Reply #19 – July 09, 2013, 10:29:25 pm

Bypassed racor filter; still quits. Replaced all fuel lines from engine to fuel pump to back inside wall of generator; from outside wall of generator to racor.......Bingo, problem fixed! Praise be to God that I didn't have to replace the line from the Racor to the main tank.....it would have gone to the shop for that one.

Thx to all for your support and guidance....could not have done it without you. Great forum Great people

Re: Kubota Generator rough idle then quits

Reply #20 – July 10, 2013, 07:55:08 am

Fiddler, Great , glad you solved it. I would keep a close eye on both the Engine and remaining genny fuel lines tho.
Gary B

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