Foretravel Owners' Forum

Back in November, we bought about 75 gallons of fuel.  One hour later, we lost full power, and very quickly pulled over, where I changed only the filter which is located in the side door behind the rear wheels and above the start batteries.  The filter was a Racor R90P.  I used the prime button in that compartment to prime the new filter.  A couple of tries got the coach running again and off we went.  This filter showed no signs of algae or foreign material, and the fuel I drained into a drain pan looked clean and bright green.

We drove about 2 hrs to our destination, had no problems. The coach ran just fine.

Next, we drove about 2 hours and things were going fine, until we had low power again (coach would only go about 40mph).  We were very close to our destination so we limped in and parked.

I took a fuel sample from the tank with @wolfe10 's wire hanger and plastic tube trick.  I also drained that same fuel filter into another glass jar.  I tried to get a sample from the fuel filter on the block, but some sludge from the outside of the filter fell into the jar and turned it black.

The samples have been sitting about 45 minutes.  They don't appear to have any water in them.

Now that I have drained most of the fuel out of the secondary filter (on the block), I'm going to change it.  How do I prime it?  Is that what the other prime button is at the top rear of the engine compartment?  Or is there some other way to refill/prime the fuel filter on the block? 

Do I also re-replace the first filter (with 4 to 4 1/2 hours on it), just so I'm starting out with both new fuel filters or do I save it, and see if just replacing the secondary (on the block) rectifies the problem.  I have 4 of each on hand.

Any other thoughts on what could be the problem?  I feel pretty certain I'm having a fuel problem, since after changing the one filter we ran about 4 hours until the problem reoccured.

We are supposed to head south to Texas tomorrow.  Currently in St. Louis, MO.

Thanks,
Douglas

I was just thinking.....theoretically, since it has been below freezing for days now, with the lows every night in the -6 degrees range, and the warmest being currently 22 degrees....if there *was* any water in the bottom of the diesel tank, it could be frozen?!?

We have been spared these "bad fuel" problems (so far) so I'm no expert.  However, since you have a ample supply of filters, I would vote to change both filters.  That way you know exactly where you stand, and if the problem reoccurs you can pretty much rule out plugged up filters as a cause.  Just my 2 cents...

I don't worry about priming the engine after changing filters.  I fill the filters with clean fuel, screw them on, and crank the engine.  Starts right up after a few seconds of cranking.  Your bigger engine may be different from our C8.3 in that regard.

When your engine is running, the return fuel warms up the fuel tank pretty quickly.  I don't think fuel tank ice would be your problem.

Douglas,

What is the condition of your fuel lines.  Look closely where the line comes in from the tank at the primary fuel filter.  These lines are on the SUCTION side of the fuel system.  So, any leaks would be air IN, not fuel out. 

Any engine codes?

Brett, all the fuel lines where replaced by PO about 5 years ago, just before we bought the coach.  They appear to be in great condition, I didn't see any cracks or anything odd.

We didn't get dash warning lights or beeps or buzzers either time we had low power.

****Edit*****
Removed photos because they were not accurate.
Here are the fuel samples after about 1 hour.

Oddly, the one on the left (from the filter) seems to be a slightly different color.

That green tint is a little unusual.  Any smell of coolant to it? Any loss of coolant from the overflow reservoir?

add biocide.  (Is there a west marine nearby?)  did fuel gel in cold?

if on jelled - have many fliers on board

gree tint - hmmmmm

Tim Fiedler

Sure Start Soft Start (http://www.gen-pro.biz)

TCER Direct (http://www.tcerdirect.com) generator-gas-prod (http://www.generatorgasproducts.com) 630 240-9139
Gen-Pro

Sorry, pretty sure they are the same, I think it was just sunlight from the kitchen window.

Neither smell like coolant.

I'll remove the above photos.

Photo with flash, look about the same.

So I add biocide if there is no visible algae?

I don't think it gelled, this all happened before the really cold weather hit.  Lowest temp when this happened was maybe 25F probably above 28F.

Also, is there a way to prime the secondary fuel filter that is under the coach up by the block?

Green tint may be a bio-diesel mix indication. Change filters with a gallon zip-lock to catch overflow. I always leave ours a turn loose and then use the primer to fill and get the bubbles out. Zip-lock works great here too. Fill primary first, tighten and then the secondary.

Again, good to have a pressure gauge at the output of the secondary filter. Easy to install. You can't read it at full load but it does give a good indication of fuel pressure at idle and condition of the lift pump.

Pierce

Douglas, check your lift pump fuel pressure and fuel tank vent.  Also, air filter and any air intercooler or turbo gate that could be a restriction. Could there be a governor issue?



Wantabe

 Douglas, the first thing I would do, is change the primary filter and cut it open to see if you have an algae problem.

I have had a few strange loss of power incidents over the last several years, but nothing in the last year.  Never did figure out what was actually causing it as it would go away about as fast as it happened.  Engine might not have enough power to get out of 1st gear in the worst case, or maybe enough to run in 3rd or 4th.  Pull over and start checking stuff, maybe shut off the engine, start it back up and have full power in most cases, or might have to do that a couple of times.  In all cases it happened when going up and down a series of moderate hills.  After the last incident, I am wondering if it could be the turbo waste gate sticking open at the top of a hill, back off on the accelerator, turbo spools down, then can not spool up with the gate open, and not much power.  Have not been able to verify that when hot it was stuck open; but when it is cold the gate opens and closes freely except there is a strong spring to hold it closed until manifold pressure gets high enough to force the gate open.  If it happens again, that is the first thing I am checking.

Jerry,

Low fuel pressure can result in low boost pressure. Suspects might be faulty lift pump, dirty injection pump relief valve, algae in filter, air leak in fuel system, etc.

Even if you have a mechanical engine, it's easy to install a boost sensor and then use one of the extra wires available to bring the reading up to a gauge on the dash. Expect you should see somewhere between 20 and 30 psi, depending on the engine model.

A boost gauge kit would look something like this: AEM 30-4406 52MM DIGITAL 35psi ELECTRONIC TURBO BOOST GAUGE - FULL WARRANTY... (https://www.ebay.com/itm/AEM-30-4406-52MM-DIGITAL-35psi-ELECTRONIC-TURBO-BOOST-GAUGE-FULL-WARRANTY/360714573598?epid=1517894828&hash=item53fc43971e:m:mWPso-HlPP-g57WqMpADtdw&vxp=mtr)

Electronic engines can use a reader to monitor boost pressure.

Pierce

As Chuck said, should not be that hard to prime:  with strong start batteries you can probably start with just the starting process, if not, from a previous post of mine, "Never ran out of fuel, thus with new fuel lines, I am hoping none start was due to cracked supply lines allowing air in and loosing prime, not switched supply pick ups.  I am now an expert in starting this 6C8.3  Even worked with new, empty of fuel lines installed.  Turned ign key on, not far enough to energize starter, pumped lift pump maybe 40 times, opened two turns #1 and #3 injector, started engine with fuel pedal to the floor until running at 1500 to 2000 rpm smoothly, shut off, tightened #1 and #3 injector line.  If it still will not start, re due above, may have to do 3 or 4 times to bleed air out.  (If you install new filters, you will have to pre fill filters).  With new lines, I can bleed and start in minutes.  I know this because I did so twice after final replacement of approx 50 inch of new 5/8 hose between filter and lift pump."

Douglas,

For 'priming' after changing fuel filter, we remove primary (over batteries) first, fill filter with diesel from a gallon container we carry, screw on, start engine, immediately go to mostly full throttle to keep engine from stalling from any air in fuel line.  Repeat for secondary at engine.

Another thing that may help you:  We ran just fine but decided to change (ourselves) fuel lift pump as a preventative, as some others have had issues.  We figured why not change it when we had time before it put us down at the side of the road.

Well you can imagine our surprise when our engine seemed to have a little more power and smoother take offs.  We could also now crest small interstate hills without shifting out of 6th gear.

So a failing lift pump could cause you intermittent power problems.

A little late, but after the lift pump surprise, we installed a dash electric fuel pressure gauge.  Wish we had installed that first.  Our engine is mechanical and only uses fuel & air to run, so the fuel pressure gauge would be a good assurance that fuel is not a problem, or is the problem.

OP has a '97 U320 with 400 hp M11.  Not sure how much commonality there is between his engine and our mechanical C8.3s.  He was probably hoping to hear more specific advice from members with the M11.  OR, perhaps they are very similar...I just don't know.

If it is like my '99 the prime button in the rear will prime and purge after changing filters. A lot of posts show removing this system but mine works fine.

Nice post and excellent advice. A failing lift pump will also cause Bosch P pumps to operate below design pressure. Part of the pump is dependent on diesel to lubricate and carry off excess heat through the overflow valve aka pressure relief valve and return line. The symptoms are much like algae in the filters.

Good idea for the dash fuel pressure gauge. EGT should also drop if the fuel pressure drops.

For Cummins owners, this may be an easy DIY fix and insure your P pump will outlast several engines. P7100 Performance Overflow Valve for Cummins OFV060HP (http://www.torkteknology.com/p7100-performance-overflow-valve-for-cummins-ofv060hp/)

Pierce

IMO, the OFV010 is a more suitable choice for a stock fuel system.  It would be possible to raise the pump inlet pressure too high with the OFV060 valve.  Just my opinion, based on what I read on the Tork Tek website.

Cummins Adjustable Overflow Valve by Tork Tek - OFV010 (http://www.torkteknology.com/cummins-adjustable-overflow-valve-by-tork-tek-ofv010/)

Thanks for all the help. 

Most of you guys are WAY above my pay grade on these things. 

I've pretty much convinced myself this is a fairly simple problem of dirty fuel filters.  I'm going with the "if it looks like a horse, it's probably a horse, not a zebra" theory.

In the last 24 hours, I have replaced both fuel filters, and thanks to the help of this forum, I figured out how to fill/purge the new filters with the system that the PO installed that seems to replace the WINN system. 

I also cut open both filters today.  I didn't find anything I would call algae, but the secondary filter looks terrible.  The inside of it is very clean looking, so I guess it did it's job?  The primary filter only has about 250 miles on it, so I'm glad to see it look clean on the outside, but the inside has some sort of small fuzzy? fiberous stuff.  Not a lot of it, but stuck in several holes as you can see from the photos.  Maybe this is gelling?  maybe not?

Here are the photos I took.

Good, no GREAT work Douglas.  And I am sure that Amanda's "supervision" was critical.

Let us know what happens on your drive tomorrow.

We ARE holding WARM WEATHER for you-- should be in the 70's here early next week.

Douglas,

After seeing the inside of your 2ndary filter Mike's thoughts were (translated to be more appropriate) "that coach should run like a spotted azz ape now"  It won't be sucking the line dry.

Pamela & Mike

Douglas,
If you feel your Fuel is gelled you ought get some Power Service Diesel 911.  It will restore your fuel.
Diesel 9·1·1® is the product diesel-engine operators call on when they have a winter diesel fuel emergency.
De-ices frozen fuel-filters — no requirement to change fuel-filters
Prevents fuel-filter icing
Reliquefies gelled fuel in minutes — no tow truck needed
Removes water from fuel system — extends life of fel-filters, fuel-injection pumps and fuel injectors
Contains Slickdiesel® for maximum fuel lubrication

It won't hurt.

John M

Vroooom vroooom.  Hope all goes well.  Your new VMSpc JIB was delivered today.  Another project awaits.