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Questions about replacing fuel lines?

My truck is a 2000 Freightliner FLD120, Series 60 Detroit with 1.3 million miles on the truck.

Lately I've noticed when pulling hills I will get "power surges", almost like I have normal full power, then I lose a little, then it comes back. I think the old fuel lines might have something to do with this problem.

Should I replace the existing lines with bigger diameter lines? Will that do me any good? Any other ideas regarding my power surges?

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I have the identical truck. I would not prioritize larger diameter fuel lines, just fuel lines that have the same inner diameter as the original. (Most hose manufacturers call this the I.D. #) Can't remember what the stock ID # is on this truck, but I will look when I get home. At 1.3 Million, it is a good idea to replace them regardless-and they-re all pretty easy to get to also.

I will speak from experience that bad fuel suction lines on that engine will cause heavy vibration while pulling (due to air going through the injectors).

Do you have a boost gauge and pyrometer? If so, are their readings changing when you notice this power surge?

How long have you had the truck? The factory Detroit ECM settings change the fuel map ( or fuel delivered to the engine at a specific condition) often during high load conditions and you may notice boost jump to 35 psi, then back down to 30.

Also, remove the primary and secondary fuel filters, cut them open and look for black or green, slimy residue. This indicates the beginning of an Algae problem ( something else I've just had the pleasure to deal with) which will cause fuel restrictions into the cylinder head.

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I have noticed some vibration when pulling and my boost gauge does fluctuate, I don't have a pyro. I've had the truck since '03 and I had the ECM replaced in '07, factory settings. I will check for algae, but I don't think I have it.

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I have a 2001 FLD with a 2000 Detroit.

I would replace the fuel lines anyway although that is not causing the surging. The fuel lines should be replaced every 5 or 6 years or 700,000 to 750,000 miles or so. When they deteriorate they don't show it outside. They swell on the inside causing a fuel restriction.

I also would like to know how ling you have had the truck.

Detroit programs the ECM to respond to the conditions such as length of pull, weight, ect. You should notice the surging at a specific RPM. Mine usually does this between 1450 to 1550 RPM's. (used to my ECM has been changed)

Now if you want to get rid of that and get full power all the time give Pittsburgh power a call, they can change the settings for you and make it a much more driveable truck.

Mine is close to 700 HP but I also have the powerbox, manifold, turbo, FASS, and free flow muffler.

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I bought the truck in '03, had ECM replaced in '07, factory settings.

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Also, I will be replacing the fuel lines. I was thinking they might be restricting fuel flow causing a slight loss of power, then letting fuel through returning full power. I should just replace them with the factory size and style line?

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Just replace them with the factory lines. My Detroit shop did mine. Then Pittsburgh power did some also. Both shops used the factory spec'd lines.

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Thanks for the info.

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Your welcome, good luck.

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Regarding changing the fuel lines... How do you buy them? 1.) OEM from the dealer, already made? 2.) Have a rubber hose distributor make them up for you? 3.) Buy the hose in bulk, and add the ends? I suppose changing the hoses, at the same time as adding the FASS system would be advisable.

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when i replaced my lines i just pulled them off myself,numbered them where they went back on took them to the local dealer had them make them an took back home an put on,saved all the labor that way,an if your going to add a fass yesw this would be a good time

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What type of hose should be used . I have a 2002 Columbia. It has rubber hose with braided cloth on the outside. I was wondering if I'd be better off replacing it with the plastic hoses the newer trucks use?

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Marc Plastic lines would be the best to use and shouldn't have to replace them

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Chris Hileman will be eternally grateful.
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