Unthinkable//Let the fuel go below 1/4 tank

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Unthinkable//Let the fuel go below 1/4 tank

June 22, 2012, 08:39:38 pm

Let the fuel tank go below 1/4 and you know the gen went off. Got to my site just as the red light came on and the gen went off. Will fill tomorrow. Will it start after fill up?? DAN

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #1 – June 22, 2012, 09:02:54 pm

Dan,
You may be lucky and it start right up. However, Don't try to start it again until you get refueled. If it does not start right away, you may need to crack the injector lines. If you try to start it now without diesel in the lines, you will guarantee that you will need to crack the lines (as more air gets into the lines). To "crack" the lines, loosen one (or more) of the nuts that hold the injector lines to the cylinders. When you crank it at first it will have air/bubbles coming out. After a moment of cranking it will have diesel coming out (and may even start). If starts, kill it retighten the diesel supply lines going to the cylinders and you will have purged the air out of the lines. Really not that difficult.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #2 – June 22, 2012, 09:10:22 pm

Actually, if it doesn't start, begin by using the electric fuel pump to bleed the air out of the fuel system. If it died from too low a fuel level, it likely has air from the tank through the primary filter all the way to the engine.

Open the air vent on the top of the final fuel filter on the engine and activate the electric fuel pump. THEN when all the air is out try to start it. If not, then crack the injectors.

Brett

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #3 – June 22, 2012, 09:22:48 pm

I would listen to Brett, he knows a lot more than I.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #4 – June 22, 2012, 09:26:39 pm

Tks so much. Got my fingers crossed, but//// now I know which way to go. Will let you know tormorow afternoon the results.
DAN

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #5 – June 22, 2012, 09:35:31 pm

OK I am not too savy. The main fuel filter has nothing on top but the in and out lines. If i follow the line out to the engine there appears to be a small bolt which may be the bleed screw. Also how you get the electric fuel pump to come on? This is the Kubtoa 10 kw gen, Tks DAN

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #6 – June 23, 2012, 09:08:00 am

I would take a jumper wire from a 12 volt source and connect it to the fuel pump power wire, of course the wire from the pump should be unplugged from the generator wire to prevent backfeeding anything else

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #7 – June 23, 2012, 09:37:42 am

Quote from: Dan J. Stansel – June 22, 2012, 09:35:31 pm

... Also how you get the electric fuel pump to come on? This is the Kubtoa 10 kw gen, Tks DAN

Dan,

We have a Kubota 10KW generator. There is a "Preheat" momentary contact switch on the dashboard of the coach. It is next to the generator "Start/Stop" switch. My understanding is that pressing the "Preheat" switch engages the electric fuel pump, as well as powering the glow plugs. I can hear a pump run when I press the "Preheat" switch.

First, get plenty of fuel in the fuel tank. I would try holding the "Preheat" for about 20 seconds, then try the "Start" switch while continuing to hold the "Preheat" switch. If the generator doesn't start, then I would try some of the methods other people have suggested. Try the easy solution first.

Our SOB coach had a Cummins 5.9 engine. A couple of times I drained a few ounces of fluid from the fuel filter to verify that there was no water accumulating in the filter. The process introduced enough air into the system that the engine didn't want to start. I never found any priming system on the coach, so I cleared the system by cranking the engine. I would crank about a minute, and then rest for about five minutes. After about three rounds, the engine reluctantly ran and pretty quickly returned to normal operation.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #8 – June 23, 2012, 09:54:18 am

Sure would be nice to have a momentary hot switch in the compartment connected to the fuel pump. Could bleed/change filters or fill hoses after changing and then prime the system without putting any wear on the starter. Would also verify the pump is working. Seems a easy installation.

Pierce

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #9 – June 23, 2012, 10:12:37 am

It should start but if not you can do as Brett said. I never let the tank get much below half a tank. My personal empty and that is 800 miles anyway and that is long enough even for me to drive. Not a huge issue to rectify..

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #10 – June 23, 2012, 10:12:44 am

Quote from: red tractor – June 23, 2012, 09:08:00 am

I would take a jumper wire from a 12 volt source and connect it to the fuel pump power wire, of course the wire from the pump should be unplugged from the generator wire to prevent backfeeding anything else

This is exactly what I do to prime the Kobota 4 cylinder diesel in our sailboat. Just disconnect the positive feed to the electric fuel pump and jumper pump end to 12 VDC positive. Open a bleed screw on secondary filter and run it until all air removed. Works very quickly and always starts right up. But, if the engine has been run completely out of fuel, it may require bleeding at the injectors if it doesn't start after 4-5 tries.

And, particularly in the summer, run on the TOP HALF of the fuel tank, as fuel is used to cool the head area in both generator and main engine. As a quick check, the next time you drive on 1/4 tank on a hot summer day, stop and feel the temperature of the fuel tank! You are loosing HP and MPG if fuel is really hot, as fuel injection is calibrated at a certain viscosity. And, at 120+ degrees, calibrations are OFF. The reason I was one of the very first to install a fuel cooler on the return line from engine to tank! It later became OE.

Brett

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #11 – June 23, 2012, 10:42:28 am

Quote from: John S – June 23, 2012, 10:12:37 am

I never let the tank get much below half a tank. My personal empty

Same here. We found out early on that the baffle design in our coach's fuel tank means we can't go below 1/4 tank at all or we'll stall on a turn and have to reprime. Fortunately we found this out pulling into a Flying J.

When it happened a couple of times we asked FT about it and learned about the baffle configuration (it took them some digging to identify the rev of our tank). There are several for 2003 alone, so others may/will be different.

Michelle

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #12 – June 23, 2012, 11:44:15 am

The tank on my 1996 must be diferent because I ran out of fuel by accident and dipping the tank showed 1 inch of fuel which is about 6 gallons. My empty mark is 10 gallons, but I know the genset will not work below 1/4 tank. Air bleeders on M11 and genset work well (as described previously in this thread). I routinely dip the tank when below 1/4 tank to allow getting lowest price on fuel.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #13 – June 23, 2012, 12:04:39 pm

Quote

I routinely dip the tank when below 1/4 tank to allow getting lowest price on fuel.

Yo Wyatt.

With that much courage I want you to move to El Centro and have my back at all times ;o)

best, paul

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #14 – June 23, 2012, 02:43:11 pm

I will put in a few gallons and then drive to where it is cheaper. IF I can not find cheap fuel in 800 miles or so I am not going to find it. Many times I top off sooner than a 3/4 of a tank so I can get all the way to the cheapest fuel. It is not really a big deal but it is fun to play that way.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #15 – June 23, 2012, 03:33:32 pm

God bless the VMSpc for fuel burn and how much in tank, for those that prefer to run low fuel level, I have to assume you love having em issues with filling filters, bleeding injectors, recycle the Aqua Hot to get it blead. My guess is that some folks just love pushing the coach to the next fuel pump.

Lot cheaper to fill a lot sooner and less strain on all concerned.
FWIW
Dave M

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #16 – June 23, 2012, 06:08:07 pm

I occasionally go below quarter full, and have had no problems. I simply do without the generator.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #17 – June 23, 2012, 06:11:09 pm

OK Here is what happened. Filled the tank took 131 gallons. I think my tank is 145. So it appears around 15 gal left the gen will shut off. Took Charles's advice and did not try to restart until fuel added. First try it ran for about 15 seconds. Second try ran for about a minute with black smoke. Third try was the charm and has been running for the next 3 hours just great. Lucky Lucky I think. Lesson never never never let the tank get to 1/4 tank again. DAN

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #18 – June 23, 2012, 06:15:56 pm

Excellent, and, yes very lucky you didn't have to bleed the generator fuel system.

Brett

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #19 – June 23, 2012, 06:20:58 pm

Brett: Tks for the information. I was ready to go on your help if it didn't run. DAN

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #20 – June 23, 2012, 07:16:12 pm

Hmmm...I've been meaning to calibrate the fuel sender unit for the past 3 years...(a full member in good standing of the procrastinators' club)...just can't seem to match the time & the will...

Peter

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #21 – June 23, 2012, 07:49:28 pm

Congrats,
I am glad that no cracking of lines or bleeding indicated. I have done some cracking of lines (just did not know better method). Thanks also for the tip on why better to fill about 1/2 during summer. Was not aware of the injector fuel viscosity parallel change when tank got lower. Makes sense, and will keep in mind.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #22 – June 24, 2012, 12:12:13 pm

When I purchased my 1996 U320, the Powertech 10K generator would run for an hour but within a few days it would only run for 30 seconds. Problem was cracks in the fuel lines letting air in and causing engine to run out of fuel. I ran the genset from a seperate container of fuel to confirm that cracked fuel lines was the problem and it ran for hours. To restart after running out of fuel, I used jumpers to connect 12v to the Onan low pressure fuel pump with the feed line in a bucket of diesel. I ran the pump for a minute before attempting to start the genset which fired instantly.

I had a similar experience with the M11 when the Winns water/air/fuel seperator allowed air into the fuel through leaky "O" rings. Because the Winns purge pump did not work, I replaced the Winns unit with a Racor water/air/fuel seperator. I ran the Racor purge pump for two minutes and the M11 fired immediately.

Because of my experiences, I am confident that there will never be a need to crack fuel injector lines on the genset or the M11 to clear air in the fuel. Thank you Foretravel for well designed fuel delivery systems.

Thanks to Brett for the warning about the higher temperature of the diesel returning to the fuel tank from the M11. I will carefully check the temperature of the fuel tank when the level drops to below 1/4 tank.

Re: Unthinkable//Let the fuel go below 1/4 tank

Reply #23 – June 24, 2012, 12:16:42 pm

Quote from: P. Wyatt Sabourin – June 24, 2012, 12:12:13 pm

Thanks to Brett for the warning about the higher temperature of the diesel returning to the fuel tank from the M11. I will carefully check the temperature of the fuel tank when the level drops to below 1/4 tank.

The same fuel temperature applies to all modern diesel engines, as they are all high bypass fuel systems-- burning only a few ounces of each gallon that goes to the engine.

Another pearl: because of the amount of fuel circulated, ALWAYS, the next time you stop after filling up and driving at least 50 miles, STOP AND CHECK THE PRIMARY FUEL FILTER for contamination. Many gallons of that new fuel will have circulated through the fuel filter.

Brett

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