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Topic: Alert to Possible Fuel System Problem with 2007 Nimbus (Read 886 times) previous topic - next topic

Alert to Possible Fuel System Problem with 2007 Nimbus

Hi folks,

I had started my first thread a little over a week ago discussing my upcoming trip to MOT to possible buy a 2007 Nimbus. I'm happy to say that we did get the coach, but wanted to alert any other 2007 owners of a possible issue.

The coach is fantastic and I was really enjoying the trip back to Virginia from Texas. However, had an incident occur about two hours from home that led to this posting. I foolishly ran the tank down to just above the 1/4 level. Did not think this would be a problem, as this would still leave about 40 gallons of fuel in the tank. Indeed, that would normally not have been an issue. I was surprised when the coach just stopped running when I pulled off the exit and stopped at the intersection about 300 feet from the station. Cutting a very long story short, 5 hours later I was able to fuel the coach up. This followed arranging for appropriate equipment to tow the coach to a truck service center where ongoing consultations with MOT service staff led us to suspect the coach, despite having a 1/4 tank of fuel, had run out of diesel.

The specific problem is that the fuel line supply to the generator had been incorrectly hooked up to the location to supply fuel to the engine, and vice versa. The generator, as you may know, is designed to shut off when the fuel tank is at the 1/4 level to avoid fuel exhaustion for the engine. The MOT staff seemed to recall this issue being found on one other 2007 Nimbus. There's not that many of these in service and, except for myself and possibly one other individual, no owner has ever attempted to drive their coach with less than 1/4 tank of fuel.

Once I had the service center staff add 15 gallons of diesel, I simply primed the air out of the fuel system from the rear, cranked it over and everything was fine. Am working with the MOT staff now to locate where to have the fuel lines switched. Until then, I will be making sure the fuel gauge never gets below 1/2 (a practice I should always follow).

I have to say we are incredibly happy with the Nimbus. It is a dream to drive and we look forward to many happy adventures in it. Also, the MOT staff have taken incredible care of us (including this little blip on the trip home).

Anyone with a 2007 Nimbus or anyone requiring additional details is more than welcome to PM me.

Thanks everyone for all your suggestions and advice throughout our purchase. Can't wait to meet you folks somewhere soon.

Don Rickey

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #1 –
Don,

Glad to hear you had a safe trip home.

We learned early on with our coach (2003) not to run below 1/4 tank as well.  In our case, the fuel slosh from one side to another during a turn can cause the level in the tank to drop below the engine pick up if we're below 1/4.  We found this out after stalling on two separate occasions while pulling in for fuel and after discussing the problem with Foretravel (they had to pull the drawings out for our revision of 2003 fuel tank; apparently there were a number of different baffle designs).  Fortunately, all it took for us to get going again was using the air purge at the engine.  We haven't had a problem since then, now that we know to be more stringent on minimum fuel level.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #2 –
There is another very good reason to NOT run low on fuel:  These are high bypass engines-- for every gallon of fuel that goes to the engine, only a couple of ounces are burned.  The rest is used to lubricate and cool the fuel injection system and in some engines part of the head. 

Quick test-- put your hand on the fuel tank (yes, the aluminum part).  When tank is 3/4 or more, it is quite a lot cooler than when at 1/4 tank. Cool fuel is more HP and better for the engine/injection parts.  Many have added a fuel cooler in the return line to the tank-- have even seen some Foretravels with this as OE equipment.  A very good idea, particularly with the location of the fuel tank-- inside where it does not get much air circulation.

The other reason-- when parking, the tank should be full to minimize condensation.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #3 –
Quote from: Michelle –
Don,

Glad to hear you had a safe trip home.

We learned early on with our coach (2003) not to run below 1/4 tank as well.  In our case, the fuel slosh from one side to another during a turn can cause the level in the tank to drop below the engine pick up if we're below 1/4.  We found this out after stalling on two separate occasions while pulling in for fuel and after discussing the problem with Foretravel (they had to pull the drawings out for our revision of 2003 fuel tank; apparently there were a number of different baffle designs).  Fortunately, all it took for us to get going again was using the air purge at the engine.  We haven't had a problem since then, now that we know to be more stringent on minimum fuel level.

Sounding like a familiar maiden voyage event with a Foretravel. Like both Don and Michelle, I ran my tank down to 40 gallons. Made a long sweeping turn at the truck stop to get to the pumps. After fueling, I made it about 100 feet before the generator quit, a few seconds later the Cummins quit.

Luckily, I got them restarted with some extended starter cranking, and all was well. I believe they both sucked air during that long sweeping turn. Interestingly, my fuel gauge is calibrated for this phenomenon, the needle is in the red zone when I have a quarter tank remaining. Seems like a waste to have 300 pounds of unusable fuel.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #4 –
I always refill about half a tank so that I can keep the fuel cooler and not have this issue.  I know that I can go lower and have but I still think it is better not to push it and have reserves incase the road stops.  I can live and boondock and not worry how long it will take to clear.  They just had a tractor trailer turn over on I 66 nerve me and had to reroute traffic. I have sometimes just pulled over into a rest stop if it is close and spent the night rather than fighting traffic.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #5 –
Quote from: John S –
I can go lower and have but I still think it is better not to push it and have reserves incase the road stops.  I can live and boondock and not worry how long it will take to clear.
We usually fill fuel at about 1/2 tank. We usually start traveling with full fresh water, empty waste tanks, some food, and ample propane supplies. We prefer to be prepared in case of any "show stoppers" due to mechanical failure, weather, illness, ...

Met a FT neighbor at the Mid-South Rally whose coach stuttered a couple of times on the way to the rally. Triana was at the rally and helped him troubleshoot the problem. Turns out that the fuel gauge stuck at 1/3 tank and the driver kept deferring a fuel stop. Fortunately, he made it to the campground. Some fuel brought to the campground in cans allowed him to make it to a fuel station.

I've not encountered anyone who experienced problems from operating on the "top half" of the tank.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #6 –
Having the VMSpc and it is very accurate, I have run it down to 62 gal left in tank, took 133.7 gal to top off, the tank should hold 194 gal,  just one reason I like and trust the VMSpc, it keeps good tabs on fuel remaining and mpg etc, etc.  But was concerned and lucky.
Dave M

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #7 –
Quote
Interestingly, my fuel gauge is calibrated for this phenomenon, the needle is in the red zone when I have a quarter tank remaining. Seems like a waste to have 300 pounds of unusable fuel.
I wonder if my 95 is set up that way. My fuel gauge is not accurate. When it reads 1/4 the tank is actually 1/2 full. However, when that gauge touches 1/4 the Low Fuel warning light illuminates and the generator quits. I am certain of the actual level as I use the VMS and also check with a probe.

I just adjusted the fuel sender unit and am anxious to see if it performs the same.
jor

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #8 –
Quote from: jor –
I wonder if my 95 is set up that way. My fuel gauge is not accurate. When it reads 1/4 the tank is actually 1/2 full. However, when that gauge touches 1/4 the Low Fuel warning light illuminates and the generator quits. I am certain of the actual level as I use the VMS and also check with a probe.

I just adjusted the fuel sender unit and am anxious to see if it performs the same.
jor

Not sure about part numbers but I bought a replacement fuel sender for my 97 from Foretravel.  Electronic.  Right on on the levels.  Finally.  No adjustments.  Takes a few refills to calibrate it to a fine level but worked out of the box.  Attach wires. 

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #9 –
I recently had the fuel gauge sender replaced at FOT. Fuel gauge is usable again. New digital sender is ~$120 for the part. Installation appeared to be easy.

I successfully adjusted the original sender a couple of times, but it finally went totally flakey.

VMSPC is not an option on the C8.3.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #10 –
I start out with full fuel and water, empty black and gray tanks. When we're in the last town before the campground I fill the fuel tank. I think the most fuel I've put in at one filling was about 50 gallons, which is about 1/3 of a tank. That was expensive enough.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #11 –
I have put in about 110 gallons as the most at one time.  Thankfully it was 2.50 a gallon then.  Now I usually put in about 70 or so at a time. 

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #12 –
The tripmeter is your friend.  I know from experience that I get about 8.3 on a consistant basis.  I fill, drive 800 miles and then look for fuel, always have a good reserve.  My fuel gauge never reads above 1/2 and has been replaced three times.  I give up. It does read accurately from 1/2 down.
Gary B

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #13 –
Quote
Not sure about part numbers but I bought a replacement fuel sender for my 97 from Foretravel.  Electronic.  Right on on the levels.  Finally.  No adjustments.
Good to hear. I'll buy one if my adjustment doesn't work. On our 99 I was able to get the adjustment just right. On our 93 I found that the inner tube on the Centroid unit was randomly coming in contact with the outer one. I rigged up a little separator and it worked fine thereafter.

Still wonder about frozenh2o's comment re the red zone. Seems unlikely that a 95 would be set up like an 03. It seems as though the warning light and generator cutoff are controlled by the gauge reading rather than the actual fuel level.
jor

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #14 –
Quote from: frozenh2o –
Luckily, I got them restarted with some extended starter cranking, and all was well. I believe they both sucked air during that long sweeping turn. Interestingly, my fuel gauge is calibrated for this phenomenon, the needle is in the red zone when I have a quarter tank remaining. Seems like a waste to have 300 pounds of unusable fuel.

While my coach is a few years older than yours and therefore not guaranteed to use the same setup, I would guess that your fuel sending unit has some gunk on it or is malfunctioning.  I also thought that FT had been extra cautious with the fuel tank readings when I bought mine, similar to the type of reading you get and just chalked it up to a quirk of the system.  After draining and refilling the tank while replacing my fuel lines, my gauge now reads dead on for the amount of fuel in the tank and something had not been working properly before. 

It's hard to know if there are particular quirks for something since most of us didn't buy these FT's new but I would guess that your fuel sending unit is malfunctioning.

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #15 –
I guess I'm the odd one here.  I've run my fuel tank down to 40 gallons with no problems.  Once I wanted to tour the Napa valley from Arizona without paying Cal fuel prices.  1200 miles as I recall.  I also ran it that low before I had FT replace my fuel lines.  Was that why my fuel lines died?  Hmmm. 
 

Re: Alert to Possible Fuel System Problem with 2007 Nimbus

Reply #16 –
Quote
I've run my fuel tank down to 40 gallons with no problems.  Once I want
Me, too. Try not to but it's not always possible. Got the 320 down to about 25 gallons once. No prob - except paying for 175 gallons of fuel or whatever it was!
jor