Isata 5 Fuel Filling too slow

[BLT4SPD]

Originally Posted by bclemens

Correct....you shouldn't be running the Gen while refueling. If you can get it to take fuel while it is running, great, but we would not change the system under warranty to enable that, if it is working without it running. (I hope that makes sense).

One of the things we have asked FCA for, is a proper fuel return line that other guys (Ford, Mercedes) build in. Ram does not, so we have to use a work around.

Brian, I asked the question earlier in the thread, but it probably got buried, so I'll ask it again:

Why does the Generator return fuel to the vent line?

I'm not asking because I want to be a smart ass or anything like that. I am asking because I don't know and I am trying to puzzle out a solution to this mystery in my head. Was that an engineered decision? Like, "Generator fuel return MUST be tapped into the vent line because X, Y and Z" ....or was the vent line more convenient to tap into? ....or something else?

[BLT4SPD]

Another thing I noticed while crawling around under there is that both 90 degree metal elbows in the fill pipe are not mandrel bent, they were bent using a traditional tubing bender. Impossible to say what affect this had on the cross section of the pipe (or if it matters in this application), but they are most certainly _not_ round in those two 90 degree bends.

Quick version for those who don't know:

When you bend a piece to tubing with a traditional bender, something has to "give" to make that pipe actually bend. On larger pieces of tubing (say 2"-2.5" and larger) the inside radius of the bend will usually get crushed inward. That effectively makes the cross section of the tube smaller. When you bend the small-ish stuff (say 3/4" to 2.0") the typical thing that happens is the pipe will turn into an oval shape. Again, this crushes the pipe and can reduce the cross-sectional size of the pipe.

A mandrel bent pipe is a process that eliminates this crushing effect by supporting the pipe from the inside while it's being bent. The ides is obvious, the pipe maintains a constant cross sectional size throughout the bend.

Here's a good side-by-side comparison I found using my friend Google:

[caseymyers]

Originally Posted by bclemens

Correct....you shouldn't be running the Gen while refueling. If you can get it to take fuel while it is running, great, but we would not change the system under warranty to enable that, if it is working without it running. (I hope that makes sense).

One of the things we have asked FCA for, is a proper fuel return line that other guys (Ford, Mercedes) build in. Ram does not, so we have to use a work around.

For awhile until I straighten out the 'P' trap of the rubber hose mine would not take fuel in any case. The test I'm going to run on Sat is to see if how it takes fuel with it on and off. Agree, if it only works with it off I'd be a happy camper. Can we get Morryde involved? Have them come over to your shop when my rig is there and use it as the engineering bench model and get the venting fixed and maybe mock up a pipe hanger?

[caseymyers]

I'd like to know what those fittings are that go to the generator, there are two of them and if one is a return line, why? Why does fuel come back to the tank? Does the fuel pump send too much, so that there is an excess? Curious.

[BLT4SPD]

Originally Posted by caseymyers

I'd like to know what those fittings are that go to the generator, there are two of them and if one is a return line, why? Why does fuel come back to the tank? Does the fuel pump send too much, so that there is an excess? Curious.

That is the nature of most engines these days and the nature of ALL electronically fuel injected engines (car, truck, boat, generator, etc). The fuel pump is designed to pump a constant volume of fuel to the engine and whatever is not used is sent back to the tank. Fuels pumps are very dumb devices in the sense that they are either on or off. They don't change speed depending on demand. What you end up with is a fuel system that is designed to deliver enough fuel to satisfy the engine at full load (plus a margin of error) and when you are not at full load, the unused amount of fuel makes a return trip to the tank.

In theory, that would mean that the return line is flowing more fuel when idling and when the engine is under load, less fuel is being returned to the tank.

That's the simplified version anyway.

As for the fittings: It is my assumption based on what I observed under our coach and what Brian has said in this thread that A) Dodge/FCA have no clue what the end use of the chassis is going to be when they build it. It could be an Isata 5 or it could be an Ambulance or it could be a Roll-Back tow truck....or.....or..... That means that they have no idea if it's going to have a generator or not and do not provide any means of supplying or returning diesel fuel to a generator. Then, when Mor-Ryde gets their hands on it and they say, "okay, this is a going to be a motorhome chassis for Dynamax and it's going to have a generator", they have to _MAKE_ the provisions for fuel supply/return for that generator. So, they cut the vent hose that (presumably) FCA installed at the factory and insert that Tee into the hose so they have a way to connect the fuel return line to the tank. The only other way to do this would be a direct connection to the tank and I give you every assurance that NOBODY with an ounce of sense wants to modify an OEM fuel tank.

Now, this leads directly into the question I have asked: why was the vent line selected for making this connection? engineered decision or a matter of convenience? ....and does it really matter? After all, the ONLY goal is getting diesel fuel back into the tank.

[caseymyers]

So maybe it is important where those hoses are connected and even at what angle and like in my case maybe the drop in that return line has created yet another 'P' trap? And maybe (I'm going to run the test) when the Generator is running there is too much fuel coming out of the return like to allow that vent to work properly? Or at all in my case?

[caseymyers]

'return line' not return like...

[BLT4SPD]

Originally Posted by caseymyers

So maybe it is important where those hoses are connected and even at what angle and like in my case maybe the drop in that return line has created yet another 'P' trap? And maybe (I'm going to run the test) when the Generator is running there is too much fuel coming out of the return like to allow that vent to work properly? Or at all in my case?

I don't think the generator return line is that big of an issue. It's simply pushing fuel back to the tank via that 8.9mm (5/16") hose and dumping it into a MUCH larger 3/4" hose that returns it to the tank. Even if there is a low point where Mor-Ryde tee'd into the vent line, it still wouldn't be an issue because it would have to fill the ENTIRE vent line back to the rear of the coach before it hydro-locked.....and it can't do that unless the entry to the tank was plugged.

Really the only time it COULD be an issue is when/if you run the gennie while pumping fuel.

Personally, I believe that the more plausible problem is the existence of those multiple brass fittings. I don't KNOW that, but it's a lot of things screwed together creating multiple places where a reduced ID is likely and one VERY sharp 90 degree turn. _I_ would LOVE to see that hard 90 turned into a smooth easy transition, but then again, all it's really got to do is vent the air that is being displaced by the incoming fuel, so does it really make a difference? I'm afraid that I don't have an answer for that....at least not yet.

[bclemens]

Originally Posted by BLT4SPD

Now, this leads directly into the question I have asked: why was the vent line selected for making this connection? engineered decision or a matter of convenience? ....and does it really matter? After all, the ONLY goal is getting diesel fuel back into the tank.

When we asked Ram for a dedicated fuel return, they said it was not available and suggested we just use the vent line for the return. We assume, it is because it is easier to find parts and pieces to go from the 5/16" line to the 3/4" line as opposed to going directly to the fuel fill line. We actually asked the supplier that we get our fuel line from about welding on a port, but they declined, I assume for liability reasons.

Now having said all of this, I think I have mentioned this before, but traveling for sales for over a decade, you learn all about different cars. I hate the Ford sync system, loved the uConnect system. I also learned that a Ford Taurus would NOT fill properly when on the outside lane of the Denver International Airport. The fuel fill was on the passenger side (as I recall) and when I was on the inside of the outside island...it did not want to fill. Not even the first notch. I learned, through trail and error that, if I went to the outside, of the inside island it would fill on the fastest setting. I can only assume that the concrete was sloped to shed water. (as I think it all is) and as such it was negating what was likely a very minimal slope somewhere in the system.

When I was in my 30FW, the very first fuel stop, I could also not get it to take fuel...even on the first notch. Every time thereafter I could get it to fill on the highest notch. In theory, I was paying more attention to orientation of the pump...but I'm not sure I really did that much.

lastly in regards to the vent...I don't think the vent line would cause any issue for filling where it was oriented in the front or the rear...as long as it wasn't on the bottom.

[BLT4SPD]

Originally Posted by bclemens

When we asked Ram for a dedicated fuel return, they said it was not available and suggested we just use the vent line for the return. We assume, it is because it is easier to find parts and pieces to go from the 5/16" line to the 3/4" line as opposed to going directly to the fuel fill line. We actually asked the supplier that we get our fuel line from about welding on a port, but they declined, I assume for liability reasons.

So, the answer is; it was selected out of convenience, not for engineered fluid dynamics reasons. That's a good thing. There are plenty of viable options out there for returning a 5/16" hose to either a 3/4" line (the vent) or a 1.5" line (the fill). I just wanted to see if one was selected over the other before I go "Shadetree engineering" my own solution.

Originally Posted by bclemens

Now having said all of this, I think I have mentioned this before, but traveling for sales for over a decade, you learn all about different cars. I hate the Ford sync system, loved the uConnect system. I also learned that a Ford Taurus would NOT fill properly when on the outside lane of the Denver International Airport. The fuel fill was on the passenger side (as I recall) and when I was on the inside of the outside island...it did not want to fill. Not even the first notch. I learned, through trail and error that, if I went to the outside, of the inside island it would fill on the fastest setting. I can only assume that the concrete was sloped to shed water. (as I think it all is) and as such it was negating what was likely a very minimal slope somewhere in the system.

....and I can tell you that if you own/drive ANY 1984-1987 Audi 4000, you MUST turn the fuel nozzle upside down to get the fuel to go into the tank at anything more than a trickle. It's just what works for those cars.

I travel a lot for work myself and those types of scenarios you've described are great, but they also fall under the ole' McDonald's "repeatable process" heading. Like, "if the rental car company gives me a Ford Taurus AND I'm at DIA, I know to do X, Y and Z to make my life easier". Change ANY part of that and you're almost back to square one. There in lies the problem in the context of this thread: you know better than just about anybody that the RV life is not conducive to the repeatable process. That's part of the "magic" so to speak. I might never fill the coach at the same gas station twice. I can keep an eye out for the right slope to the pad or whatever "trick" makes it work. However, I don't think anybody (including yourself) wants to pull into a gas station and wonder how long it's going to take this time....or am I going to get covered with diesel...or it the coach going to get cover with diesel....or....or...or. It should just be as simple as putting the nozzle in the hole and squeezing the trigger. Anything less than that is a design flaw in my opinion.

[bclemens]

Originally Posted by BLT4SPD

Change ANY part of that and you're almost back to square one. T

In theory...but that scenario at least gives us good data to try and determine root cause. Failures are sometimes just as telling as successes. In a car, you are dealing with about 19-20 feet, with the fuel tank much shorter than that. In an RV it is a whole other animal when talking slope.

This came up today in talking about leveling jacks. "Level" has a degree of tolerance. 1/4 bubble is the tolerance for jacks. So some people think...I hit the button and it gets spot on every time, otherwise it is broken.

If it were a car...no big deal. You could hardly tell the difference. 1/4 bubble on a 40' RV is 5/16" per foot as I am told. Plumbing is 1/4 per foot in some cases. So in theory, you could level the coach and if it was not perfect from the start and there is a 1/4 bubble variance the wrong way, you have effectively negated gravity. Again, in theory, you could try and compensate that by doubling everything up...but there is not scientific approach to that as I have learned there is no scientific way to determine all the possible crazy scenarios that customers may find themselves in. Experience, unfortunately can be the slowest teacher.

[BLT4SPD]

Originally Posted by bclemens

In theory...but that scenario at least gives us good data to try and determine root cause. Failures are sometimes just as telling as successes.

I couldn’t agree more!

Originally Posted by bclemens

In a car, you are dealing with about 19-20 feet <snip>….

What the heck kind of car are YOU driving?!?! I once has a 1964 Cadillac Fleetwood and it was 21 feet long, but that’s not repeatable with today’s cars.

Originally Posted by bclemens

<snip>…..as I have learned there is no scientific way to determine all the possible crazy scenarios that customers may find themselves in. Experience, unfortunately can be the slowest teacher.

I hear you Brian, I really do. I think I speak for most people here when I say that I am not expecting you or Dynamax to plan for and accommodate every possible scenario. I’m just really struggling with this one. My coach is “level”, as per the equalizer leveling jacks, right now in my driveway (the 1/4 bubble fudge factor may apply) and that scenario SHOULD be planned for. Yet, the low point of my fill pipe is SIGNIFICANTLY lower than the entrance to the fuel tank. Those two points along my fill pipe are probably 3 feet apart, so apply the 1/4 bubble all you want. That’s an arrangement that is going to make fueling any type of vehicle VERY difficult. The best case scenario is that it’s a bad install and a worst case scenario is that it’s a bad design. Not to mention the fact that it does not fall in line with Dynamax’s own drawing that has, in bold letters across the top:

“”IT IS CRITICAL THAT YOU MAKE SURE YOU HAVE THE LISTED SLOPE AND THERE IS NO AREA THAT CAN CAUSE FUEL TO POOL ON EITHER THE SUPPLY OR VENT LINE. BE CAREFUL YOU DON’T CAUSE A RUNNING TRAP. THIS WILL CAUSE FUEL TO BACK UP AND SLOW FILLING OF THE TANK”

Those are Dyanmax’s words not mine. Yet that EXACT condition exists on our coach (and presumably others).

Who pays the bill for cloths that are covered in diesel fuel (replacement or cleaning)?

Who pays the bill for paint repairs when diesel fuel spills down the side and it’s not cleaned up immediately?

Who is going to fix this problem? Dodge has proven they aren’t interested. Dynamax dealer? Take it back to Mor-Ryde in Indiana?

Who is actively working on a solution for this?

Is there a new procedure in place at Dynamax so Isata 5s that are currently in production (and in the future) are not going to have this problem? (a.k.a. is Dynamax improving their product based on feedback from the field?)

…..and why is the entire length of that fill pipe hanging from zip ties?

[BLT4SPD]

Originally Posted by LandKKnight

After reading this thread to my DH he crawled under our coach and found the sagging on the fuel line. He fixed it with a stainless steel pipe clamp to the storage bay by drilling 2 holes, it had been supported by a zip tie to electrical conduit! (Oy, Brian...). When he got it straight he could hear fuel drain into the tank from where it had pooled at the sagging point. We actually never had a fill problem but thanks for the heads up post, now we never will!
Linda

Curious, have you fueled your Isata since doing this mod? Results?

This is _sort of_ how I envisioned fixing ours as well.

[LandKKnight]

Originally Posted by BLT4SPD

Curious, have you fueled your Isata since doing this mod? Results?

This is _sort of_ how I envisioned fixing ours as well.

Yes, several times, no issues at all. But we have the 30fw, the "anatomy" of the problem might be different than on the bigger I5.

[BLT4SPD]

I made some progress on this issue today…..at least I think it was progress….

I pulled the entire filler tube/breather tube assembly out from under the coach. The odd thing was that the breather tube had a significant amount of diesel still in it. I have lifted the fill pipe as high as I could many times and could hear fuel run into the tank, so it was quite a surprise to find even more fuel in it. I think this points to the fact that Casey was right about part of this being a breather issue. If that breather tube had diesel in it, that means that it was at least partially blocked and maybe not able to flow enough air as you fueled the coach. I _think_ what was happening what that since the fill tube didn’t have enough slope, that would also lead to the breather tube not having enough slope….makes sense, since they are welded together. However, once you start returning fuel into that breather pipe AND it doesn’t have enough slope, that probably opens the door to fuel to getting trapped in there as well. It’s for this reason alone that I would rather return fuel to the filler tube, but I decided to go down the same path as Dynamax and keep utilizing the breather side. I honestly believe that the filler tube is a better choice, but we shall see how this works out.

Here’s what I bought and/or used:

• An 18mm (3/4”) water temp sensor hose adapter. These are used by car guys who want to add a water temperature gauge to their car, but don’t have a place to install a temp sensor. This adapter allows you to splice into a radiator hose and just like that, you have a place for a temp sensor. They come in a variety of sizes from a variety of manufactures including 1.5”, which is what I would use if I were to do this on the fill pipe instead of the breather pipe.
  
• A 90 degree fitting that is 1/8” NPT on one side and 5/16” hose barb on the other side.
  
• A 25’ roll of 3/4" fuel hose (25’ is WAY too much, but it was all I could find on the QT AND have it delivered to my door)
  
• 3’ section of 1.5” steel spiral reinforced fuel hose (Again, 3' is WAY too much, but this is pretty specialized hose and buying it by the inch isn't that easy.....and it's probably not needed, but better to have and not need…..)
  
• Hose clamps! I keep a WIDE variety of hose clamps stocked in my garage, so I replaced all the clamps too (again, probably not needed, but several of the clamps that were already installed were those cheapy clamps with slits cut in the band and allow the rubber to squeeze thru over time

After getting the fill tube out, I had to get most of the wiring harness moved and out of the way. Dynamax had the bulk of the wiring harness mounted above the fill tube, so getting the fill tube ABOVE the inlet to the tank necessitated cutting all the wire tires that were holding the harness up and simply move it aside while I re-installed the fill tube. Here’s the “fun” part, there ARE brackets welded to the chassis (as spec’d out in dynamax’s drawing) that are there specifically for mounting this super long filler tube. It just appears, that for whatever reason, Dynamax only utilizes them as a place to hook a zip tie. Come to find out, the beauty of these brackets is that they work EXACTLY as they are designed to work! With the fill tube tied up tight to the two brackets provided, the fill tube has a great slope and everything ends up ABOVE the inlet to the tank! It’s magical! The downside is, I had fully planed on needing to fabricate my own brackets of some sort and didn’t procure anything to actually attach the fill tube to these existing brackets. So, I have the fill tube tied tight to the brackets with zip ties purely for mock-up and getting my hoses installed. I’ll make a trip to Napa tomorrow and see what they have for exhaust clamps (or something) that will provide a more permanent attachment.

The first picture below is the ‘before’ picture and exactly how it left Dynamax. It hard to see, but there are multiple brass fittings to A) connect to the breather tube B) provide a point to return diesel fuel from the generator and C) make the 90 degree turn towards the tank. If the entire fill/breather pipe had the correct slope and didn’t end up lower than the inlet for the tank, this conglomeration of fittings would _probably_ work, but it’s a tad “clunky” for me. It’s a lot of thread connections and it seems like there is a lot of room to have a smaller inside diameter than the 3/4” breather. It also may work fine, but I just wanted to “clean it up” a little bit.

With my new arrangement of fittings, I’ve traded the threaded connections of the brass fittings for hose clamps which isn’t necessarily a good thing….or a bad thing as they both represent possible points of failure. What I HAVE gained from this set up is a very clean and smooth bend into the tank. It’s all 3/4" hose which I know has a consistent inside diameter and it only has to make ONE transition in size which is at my blue fitting.


Lastly, I replaced the 1.5” filler hose just for good measure. Nothing wrong with what I pulled out, just wanted to KNOW what I had under there.

Now, I have yet to actually go out and try and fuel the coach yet. I have a few other projects going on right now that are preventing me from actually driving the coach, BUT I _feel_ really good about it. The pipe has a GREAT slope and the entire schmeere is above the inlet to the tank! VERY excited about all those facts. If this doesn’t fix the problem, my next step will be to undo everything I just did to the breather hose and just run an uninterrupted piece of hose from the tank to the pipe. Then recreate what I did here just on the fill pipe and return generator fuel to the fill pipe instead of the breather pipe.

I’ll report back after I make it to a fueling station, but my hopes are high!

[caseymyers]

Really makes sense that what you are doing will work. I’m convinced it’s a venting issue. Yesterday’s refueling proved that it will take fuel faster with the generator off. 30 gals ~ 10 min’s. I may have to get part numbers from you. Maybe BC’s team will come up with a fix too.

[Bill Davis]

Sounds like it needs to be a recall.

[BLT4SPD]

Here is today’s progress……

I made my way down to the local Napa and picked up two 2.125” exhaust clamps. The goal is to use these to simply bolt around the fill tube/breather tube assembly and affix it to the chassis with the two brackets that Dynamax originally intended for this purpose. Of course, the bolt spacing isn’t the same on the exhaust clamp as it is on the chassis bracket. So, in the second picture you can see where I drilled a hole in the “saddle” of the exhaust clamp to line up with the bolt spacing on the Isata chassis.

In the next picture you see how I used a 6mm bolt/nut/washer in my newly drilled hole to hold the saddle on the chassis while I lifted up the fill tube and installed the rest of the exhaust clamp.

Then all it took was installing the two nuts that come with the exhaust clamp and tightening them just enough to hold the fill tube firmly, but not crush it. Part of the reason I got exhaust clamps that were noticeably bigger than necessary is because I knew that tightening those bolt firmly would crush the tube, so I wanted enough thread sticking out the top for me to double nut them (which I have not done yet).

I'm also going to experiment with some hose around the U-Bolt and something rubber in the saddle to protect the fill tube. It would be better if it wasn't metal on metal, but by the same token, the fill tube isn't going to move anymore, so it's not critical. I just have to make sure that there is enough threads left on the U-Bolt to double nut it because that'll be more important in the long run.

After all this, it’s just a repeat of this on the bracket that is further forward on the chassis. However, that one will be a tad more challenging as there quite a bit of wiring going on around this bracket, including some 120v stuff that is in flexible conduit and it’s not wanting to move very willingly. I’ll figure something out because I REALLY want to use that bracket.

[bclemens]

PS....because I see this a lot. "Recalls" are for safety related issues, not nuisance or fit and finish issues. TSB's would be more for that.

[BLT4SPD]

Originally Posted by bclemens

PS....because I see this a lot. "Recalls" are for safety related issues, not nuisance or fit and finish issues. TSB's would be more for that.

I’ve spent plenty of time in my life working inside car dealerships (not in sales mind you) and I agree that recalls are safety related and a Technical Service Bulletin (TSB) or a Service Actions would fall more in the “voluntary” category. This one is right on the edge in my opinion. I mean, having fuel back up out the filler onto the person pumping fuel and/or onto the ground could pretty easily fall under the “safety” category. Diesel fuel in an owner’s eye or mouth seems like a VERY real possibility with this problem.

To be clear, I am not saying that this is a recall. I am saying that this _could_ fall under the category of “safety” pretty easily.