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Topic: Engine fuel return line (Read 911 times) previous topic - next topic

Engine fuel return line

It seems that the engine fuel return line is leaking just after the attachment on the fuel manifold.  Anyone have this problem?  Any suggestions?
Thanks, Mike
Mike Brady
'97 U320 SE. #5137
'13 Honda Fit
Willow Springs, MO

Re: Engine fuel return line

Reply #1 –
Mike,
On our 97 U320 we just replaced that line about a year ago. We have a return fuel cooler that the hose goes to and was about 8 to 10' long. Once we got it out the hose was cracked where the hose was pushed up on the fitting. We went down to the local hose store (Stewart hose) and got a new hose compatible with ULSD and were able to reuse the same fitting.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine fuel return line

Reply #2 –
On mine, the actual hose is seeping about 2 inches from the fitting to the engine assembly, where it makes the turn forward.  This hose then goes forward into a large bundle and continues into the coach.  I have not traced the line any further yet.  Is this the line you are talking about?  Where is the cooler located?  MOT indicated that this was an expensive job to replace the hose, and I'm 600 miles from MOT.  What is involved in accessing the channel that this hose runs in to the forward part of the coach? 
Thanks for the help.
Mike
 
Mike Brady
'97 U320 SE. #5137
'13 Honda Fit
Willow Springs, MO

Re: Engine fuel return line

Reply #3 –
Mike,
If you don't have a fuel cooler then the line runs straight to the center tunnel of the coach back to the fuel tank. You will most likely have to remove all the covers (the tin ones that are located on the roof of the basement) to be able to install a complete new hose. Depending on where your return line goes into the fuel tank will determine if the tank will have to be removed so you can get to the fitting. There have been some that have came up with other ways to access this fitting like installing a deck plate under the carpet, using special built wrenches, etc. Yes it is a pretty big job especially if you have to pull the fuel tank.

The other option to get you by would be to find a convent place to splice in a new piece of hose into the return line and patch the hose with a spliced in section till you can get where you can replace the complete line. This could be done with a couple of feet of hose and a hose splice. A couple of thoughts about this patch is that the old hose may be bad stiff and make it almost impossible to put a splice into the line. The other thing is that the old hose may split due to it being brittle from age and heat so keep this in mind when you are looking for a spot to splice in to.

Our fuel cooler is located over in front of the radiator just behind the louvered cover on the right side of the coach.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine fuel return line

Reply #4 –
Ok, thanks alot.
Mike
Mike Brady
'97 U320 SE. #5137
'13 Honda Fit
Willow Springs, MO

Re: Engine fuel return line

Reply #5 –
Hi Pamela and Mike
We have a 97 U320 as well but don't have the fuel cooler on ours.  Bob and I think we need one to help preserve the fuel hoses which we replaced 2 years ago (What a job that was!!)  Can you tell us what size you have on your coach?  Thanks!  Faith
The selected media item is not currently available.Bob & Faith Rozek
1997 U320 40'
Xtreme Remodel
2010 Scion XD

Re: Engine fuel return line

Reply #6 –
Faith,

We will look up the info this afternoon and see if we can get it to you.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine fuel return line

Reply #7 –
Bob & Faith,

Here is something that is close to what we have: Genuine Fluidyne Extra Heavy Duty V8 Towing RV Automatic Transmission Cooler New
It drops the temp to just above ambient. If you replaced your own fuel lines this is just a simple tie in with a couple of hose clamps and a bracket or two.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine fuel return line

Reply #8 –
Suspect I was one of the first to use a fuel cooler on a Foretravel in the fuel return line many years ago.

But, I used a much more robust Hayden 016005.  The exact part number depends on what fittings you want to use to connect to the fuel lines. Pretty easy to remove return line from engine and attach to the OUT of the cooler.  Buy/have made at any hose shop a new line from engine to cooler IN.

I made a cover for the cooler from canvas with velcro attachment to cover the cooler in the winter-- it is possible to overcool the fuel as well as allowing it to run too hot (which it WILL do in the summer).

Installed it in front (outboard) of the CAC.

Hayden Industrial Products
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Engine fuel return line

Reply #9 –
Ii am planning on attempting this replacement job myself.  Can anyone tell me if I will be able to access the point of return on the fuel tank without tank removal?  Are there any suggestions or points of interest that I need to know about this job?

Thanks, Mike
 
Mike Brady
'97 U320 SE. #5137
'13 Honda Fit
Willow Springs, MO

Re: Engine fuel return line

Reply #10 –
Does any know the maximum fuel flow rate on the M11 injector pump?
The selected media item is not currently available.Bob & Faith Rozek
1997 U320 40'
Xtreme Remodel
2010 Scion XD

Re: Engine fuel return line

Reply #11 –
A stock IP should do 1175 pounds of fuel in one hour running at 2100 RPM.  But most of the fuel will be returned to the fuel tank.
1994 U225
build #4514

Re: Engine fuel return line

Reply #12 –
What is a stock IP? I came up with 2.8 GPM with a gallon weight of 7.15 lbs.
The selected media item is not currently available.Bob & Faith Rozek
1997 U320 40'
Xtreme Remodel
2010 Scion XD

Re: Engine fuel return line

Reply #13 –
It might be interesting to shoot the temps of supply and return lines with an ir thermometer after running a few hours, compare with ambient.  I suppose a lot would depend upon how full the diesel tank is. 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Engine fuel return line

Reply #14 –
I'm heading to Nacogdoches on Saturday and plan on doing just that.
The selected media item is not currently available.Bob & Faith Rozek
1997 U320 40'
Xtreme Remodel
2010 Scion XD

Re: Engine fuel return line

Reply #15 –
Bottom line is that fuel is used to lubricate AND COOL the head/injection system.

And, unlike OTR trucks and even most other motorhomes, our fuel tanks are very well "insulated" in the basement.

As fuel level lowers, yes, fuel temperature rises. 

All one has to do to understand this is put your hand on the fuel tank in the summer when you are below 1/2 tank and have been on the road for a couple of hours.


A fuel cooler will bring fuel return temperature down to a few degrees over ambient.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Engine fuel return line

Reply #16 –
The fuel is also used to cool the ECM on my CAT 3176B.
Rick