Engine/Transmission (1994 - 1998) '98 Fuel Supply and Return Lines

[CTD12V]

Sorry if this has been posted before, but I couldn't find an answer in my searches. I have been noticing that my truck is getting harder to start sometimes, so I am thinking about replacing the supply and return lines. Over 120,000 miles and never been touched, as far as I know. The Haynes manual and a couple of posts I saw mention that on the '98s the fuel return lines are metal inside the rubber, so you can't pinch them off to check fuel pressure without inserting a piece of test hose. My question is, does this style of metal-inside-rubber fuel line tend to develop the infamous air leaks like so many people have posted about, or am I probably wasting my money replacing them since they aren't actually leaking fuel?



Thanks,



CTD12V

 

[KWentling]

I replaced them on my '98 12-valve. Mine were not metal inside rubber, but rubber inside a plastic or vinyl sheathing. My air leak turned out to be at the electrical plug on the fuel heater. Unplug it and if the plug is wet, there is you're leak. My fuel lines from the engine to the frame were perfect, but you can't tell that until you cut the covering off. The other thing I would look at is the hose from the overflow valve line to the line by the fuel filter. It's tucked up under the intake and is subject to heat. Some have had the steel line develope a crack at the support bracket. Mine hose was checked but I don't think it was leaking. If you do replace hoses, make sure they are diesel fuel rated. I got mine from LarryB's.



Kim

 

[wcjp]

When replacing my supply/return lines it turned out my major problem was the fuel preheater/lift pump soft line. I also had a minor issue with the fuel preheater strainer and gaskets. If you have to buy the kit purchase from Cummins. The fuel preheater kit from Cummins was about $14, Dodge wants $40 for the exact same thing.



I did mine before Larry B came out with his fuel line replacement kit. I used Coast Guard approved diesel fuel line available at a local boat supply store. It's twice the thickness of the Mopar line.

 

[CTD12V]

Thanks to both of you for the input. Kim, did LarryB's kit include hose for the short section that joins the fuel preheater and the lift pump, as wcjp mentioned? It almost looks like that short section is a larger diameter hose than either the supply or return lines.



CTD12V

 

[KWentling]

I believe my first go around he was only supplying the two hoses from the frame to the engine. I traded a few e-mails with him and he sent me slightly longer lines for the frame and the short hose for the overflow line. (no charge!) He was finding that the '98's were a different set up and he was probably going to put together a seperate kit for them. He said he was going to get back with me on that, but never did. Don't know if he did the kit or not. I didn't replace the hose at the fuel pump. I'm having issues again so I'll take a look at that also. May just be that I need to tighten clamps. If you haven't upgraded you're starter contacts yet, he's the man for that too.



Kim

 

[CTD12V]

Thanks for the info!