Replacing fuel lines

[Preston W]

We have a 1998 Monaco Dynasty and I'm wondering at what point do we spend the money to replace all the fuel lines?  We have a Cummins 8.3 L engine and there's been a problematic hose that can split on weak spots, and leaks fuel . I understand that for some reason Cummins has a fuel line that goes back to the tank and pumps fuel in it.  I'm not sure if that cools components of the engine or what but that line has leaked repeatedly and caused huge problems. if you're on the road and have a fuel leak, you might as well have dynamite on the rig. Nobody wants to touch it.  Good Sam road will not respond.they'll tell you to call a fire engine and 911.  we had a leak  at a Love's truck stop and  the mechanic wouldn't go near it it because it was leaking fuel, so I've learned to get small hose clamps and  splined brass connectors from an auto parts store. It's a crazy situation because I have to have the wife start the engine to see where the fuel is spraying from.   Then I'll cut the hose where the leak is and do an on the road repair. Other wise, we are  getting towed in and a huge disruption to the vacation. We paid Freightliner $3,000 last year to replace that weak hose all the way back to the fuel tank only to discover this year, an  8-in section of hose was not replaced that went to the fuel filter and that was spraying fuel around a bracket. I have a picture of the connection that rubbed on the hose. So I just  replaced that as well but wondering how much more I should do on an older coach. It  presents  a dangerous  situation.

Edited December 2, 2023 by Preston W
Spelling error

[Dr4Film]

Fuel lines should not be coming in contact with stationary objects that can wear a hole into the fuel line from vibration of the engine. That means they did not allow enough hose going from point A to point B.

To prevent any fuel line from abrasion I would isolate it by stuffing a rubber foam insulation pad between the stationary object and the fuel line.

Not sure about longevity of fuel lines. I guess it depends on what they are made of.

[Preston W]

I agree but the first several leaks we had from that fuel line that went back to the fuel tank, were  in a big bundle of lines secured by tie straps. You can't imagine a worse feeling than being on vacation starting to smell fuel, seeing fuel  dripping down from the engine,  and then  and having to cut apart a bundle of lines and wires to find it!

The one we just repaired this summer went through the metal loop on the engine to tje fuel filter and was wearing away gradually on that metal clamp. We have 142,000 miles on the engine so it lasted that long, but just not engineered well.

[Walker]

Have you thought about using braided line?

[Preston W]

Thanks. I don't  know anything  about  it. Would that be just around the engine or all the way up to the tank? How does that compare in cost to standard fuel lines, I wonder?

[jacwjames]

2 minutes ago, Preston W said:

Thanks. I don't  know anything  about  it. Would that be just around the engine or all the way up to the tank? How does that compare in cost to standard fuel lines, I wonder?

A braided line will be more expensive, not sure how much.  And you shouldn't use it with a simple hose band clamp that is used in the picture.  Best to have the fitting with a ferrule that is crimped onto the hose.  A wire braided hose is much more resistant to wear/rubbing. 

I decided not to use the hose provided in the FASS kit that I bought for the line feeding the pump, measured how long of hose I needed and went to NAPA and had one made up. 

The hoses on my rig are all wire braided with crimp fitting.  The fittings are JIC 37 degree flared fitting. 

In your picture it has a banjo bolt, I'm sure NAPA could match it up if you decide to go with the braided hose.

[Preston W]

Sounds like an absolute  bombproof fix. I use to have an airplane and seems to me, we used Teflon aeroquip fuel hoses that held up much longer. 

[Walker]

You can look up -an fittings at summit or jegs to get price ideas.  Any local speed shop should be able to help you, if you can find one.  

[Preston W]

Thank you. I think my biggest concern is the 25-year-old fuel lines that come from the Dynasty  fuel tank to the engine, in the channel above the storage bins and what is the realistic life of those rubber hoses?  it's a big job to change them, I am sure. I would love to find out what the cost involved was for people who've done it.

[Craggar]

I use to use braided steel hose alot when I had my shop but switched over to this  https://www.jegs.com/p/JEGS/JEGS-Pro-Flo-350-Series-Black-Nylon-Braided-Hose/761335/10002/-1 when it came out and my hands were much happier. It's much easier to work with and still has a nylon braided cover to help protect it. You can buy pretty much whatever hose and you need and no special tools needed to make up a line. Steel braided is more resistant to wearing through but I never had an issue using this hose in a bunch of different applications.

[Preston W]

Thank you much. Did you replace all fuel lines from the tank?

[dl_racing427]

1 hour ago, Craggar said:

I use to use braided steel hose alot when I had my shop but switched over to this  https://www.jegs.com/p/JEGS/JEGS-Pro-Flo-350-Series-Black-Nylon-Braided-Hose/761335/10002/-1 when it came out and my hands were much happier. It's much easier to work with and still has a nylon braided cover to help protect it. You can buy pretty much whatever hose and you need and no special tools needed to make up a line. Steel braided is more resistant to wearing through but I never had an issue using this hose in a bunch of different applications.

I've used a bunch of SS braided AN hose, and yes, I've shed some blood installing those fittings. 😱
I've decided to go with nylon braided hose for everything but fuel lines on my new race car.

The nylon hose is still a bit of overkill for a coach, but it does work very well.

On 12/3/2023 at 12:12 PM, Preston W said:

Thank you. I think my biggest concern is the 25-year-old fuel lines that come from the Dynasty  fuel tank to the engine, in the channel above the storage bins and what is the realistic life of those rubber hoses?  it's a big job to change them, I am sure. I would love to find out what the cost involved was for people who've done it.

The biggest thing that affects fuel lines on an older coach is the horrible low-sulphur fuel that's mandated these days.
It's also hard on gaskets and o-rings.  I had to replace all the o-rings on my Ford Superduty after they changed the fuel.

[Preston W]

Oh boy, that's not good

[Craggar]

1 hour ago, dl_racing427 said:

I've used a bunch of SS braided AN hose, and yes, I've shed some blood installing those fittings. 😱
I've decided to go with nylon braided hose for everything but fuel lines on my new race car.

The nylon hose is still a bit of overkill for a coach, but it does work very well.

The biggest thing that affects fuel lines on an older coach is the horrible low-sulphur fuel that's mandated these days.
It's also hard on gaskets and o-rings.  I had to replace all the o-rings on my Ford Superduty after they changed the fuel.

Why not for the fuel lines on your car? 

[Tom Cherry]

On 12/2/2023 at 1:39 PM, Preston W said:

We have a 1998 Monaco Dynasty and I'm wondering at what point do we spend the money to replace all the fuel lines?  We have a Cummins 8.3 L engine and there's been a problematic hose that can split on weak spots, and leaks fuel . I understand that for some reason Cummins has a fuel line that goes back to the tank and pumps fuel in it.  I'm not sure if that cools components of the engine or what but that line has leaked repeatedly and caused huge problems. if you're on the road and have a fuel leak, you might as well have dynamite on the rig. Nobody wants to touch it.  Good Sam road will not respond.they'll tell you to call a fire engine and 911.  we had a leak  at a Love's truck stop and  the mechanic wouldn't go near it it because it was leaking fuel, so I've learned to get small hose clamps and  splined brass connectors from an auto parts store. It's a crazy situation because I have to have the wife start the engine to see where the fuel is spraying from.   Then I'll cut the hose where the leak is and do an on the road repair. Other wise, we are  getting towed in and a huge disruption to the vacation. We paid Freightliner $3,000 last year to replace that weak hose all the way back to the fuel tank only to discover this year, an  8-in section of hose was not replaced that went to the fuel filter and that was spraying fuel around a bracket. I have a picture of the connection that rubbed on the hose. So I just  replaced that as well but wondering how much more I should do on an older coach. It  presents  a dangerous  situation.

Someone raised the question of "how about your car".  I will comment on what a top notch service manager told me.  We were looking at an older Impala for our GS.  Everything looked great.  Had it inspected by our Caddy dealer, who works on all flavors of GM as well as others.  They said... BEWARE.  

WHY.  This car came from Queens.  It was NOT, supposedly driven during any snowfall event.  The lady was meticulous and her dad was a super DIY and car guy...and did all the work on several of his Vettes.  SO...WHAT HAPPENED.  As best we can figure, the real issue was driving AFTER the event when the snow and salt and such was melting.  The car was NOT undercoated as some vehicles in the NE are by a professional aftermarket service.

The rust was beginning to become evident say, 5 years ago, right before the lady's father passed away.  It was sort of obvious that someone had used a bunch of spray cans of "undercoating" and really did "lay it to it" and sprayed just about anything that didn't move.  PROBLEM....the lines were already corroded.  In addition, the brake lines were showing surface rust and deep corrosion.  The Caddy Dealer had just replaced about 1/2 of the run on a mid to older Caddy.  SAME scenario.  They would have had to almost pull the body to get the new lines run.  SO, they went to a spot on the line that looked OK...on both ends...cut and spliced.

Folks our our racing and other heavy duty mechanics know how to do this and they have the tools or the jacks or the patience to do it and they do it right.  When the shop rate is $175 per hour and it is a "boa constrictor" job, the labor just eats into it.  The total for the half of a fuel line....on the supply and NOT the return was close to $1500.  NUFF SAID....if you think about the brake lines and the fuel lines....

BUT, as many have said...  if the lines are installed and have the proper hardware to prevent abrasion and also can be visually inspected for rust....then not an issue.

BUT, if there are service points where a line needs repair...then using a high performance or vibration resistant SS line is the only way.  Out MH's vibrate in such a manner that some folks have said or read articles that driving a MH would be like building a house on an active seismic line and the tremors were 24/7....and it would be a 4.- 5 event.

 

[dl_racing427]

6 hours ago, Craggar said:

Why not for the fuel lines on your car? 

I'm still using stainless braided line for the fuel lines, just for the added safety in a crash.  Less likely to get cut or pulled apart.

[Preston W]

Excellent  point. Didn't think of that angle  but should  have.