Replacing fuel lines

Len Silva · November 21, 2006, 01:09:41 PM

I have a major fuel leak in my 4104. It is leaking above and behind the rearrmost bay bulkhead, just in front of the rear wheels. I can't see the source until I can get under it for a closer look.

I'm not sure if it's the supply or return line as I was using an electric pump at the tank in my attemps to get it started (earlier thread - stuck injector)

The existing lines are 3/8" copper tubing with flared fittings. I could use the same thing but I'm open to sugestions for a different material to use which might be easier to install. I will have to remove my waste tanks as well as the fuel tank and a lot of other stuff to get into the tunnel from in the bays. I think I want to replace both lines from the tank to the engine compartment.

I have seen others use DOT airbrake tubing for this, what do you think?

Thanks,

Len

TomC · November 21, 2006, 01:30:02 PM

Most new trucks use plastic fuel lines. Advantage-they don't dry out and are not porous. Easy to work with (just cut and slip fittings on the end-much like the Qest water fittings) I used smaller version of the line for my gen and it works just fine after 12 years. Copper flaired is fine, but you sure need to know what you are doing so not to over tighten the joint and crack the flair. I know others will say only Aeroquip or equal. Freighltiner has been using the plastic lines now for years with no real systemic problems. As with any fuel line, you should fully support and insulate it from vibration and rubbing. Good Luck, TomC

Len Silva · November 21, 2006, 01:41:05 PM

I was just thinking that rather than going through all the work of opening the tunnel, I would run 3/4" plastic conduit from the tank to the engine compartment and put the two plastic lines in that. Got to go look and see what kind of project that might be.

Len

TomC · November 21, 2006, 02:48:23 PM

Just run the lines and forget the conduit-more work that is unneccessary. Good Luck, TomC

Len Silva · November 22, 2006, 05:50:14 AM

OK, so where do I find plastic fuel line and what about using air brake nylon tubing? I have seen it used for fuel lines but I'm not sure it's the best way to go.

Len

TomC · November 22, 2006, 08:45:18 AM

You have to use fuel rated plastic lines. I know you can get them at most any big rig truck supply house, or truck dealers. Good Luck, TomC

rayshound · November 22, 2006, 12:04:16 PM

I was wondering the same thing myself. I have a 30 year plus mci-8 with the original fuel lines. They work fine but before I close off the center walk on the floor, (the old a/c duct) I'm wondering if I should replace the fuel lines. They are not giving me any problems but the access is easy now and not so easy later. Ray

niles500 · November 22, 2006, 01:50:27 PM

Ray, unfortunately you mentioned it now - and you'll have to do it - cause you know its gonna come back to haunt you - a subset of Murphy's law will ensure it -

Hartley · November 22, 2006, 03:36:09 PM

Quote from: Len Silva on November 22, 2006, 05:50:14 AM
OK, so where do I find plastic fuel line and what about using air brake nylon tubing? I have seen it used for fuel lines but I'm not sure it's the best way to go.

Len

Len,
Contact Amazon Hose in Orlando for the lines and fittings, They have virtually anything and everything that a person could image in hoses
and stuff to hook them up. Prices aren't bad either.

rayshound · November 22, 2006, 07:14:59 PM

Thanks Niles, I wanted to replace them anyway, I was looking for a good excuse. Ray