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Gas line size


Steve_RI
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Thanks, I picked up a double flare kit anticipating changing all brake and fuel lines in the spring.  My brother in law had a roll of 5/16 nickel copper tubing and gave me 10 feet of it... enough for now.  The only thing left is to figure out what connectors I need for the ends? 

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One of the outlets on the fuel tank sending unit snapped off at the base..part is friggen expensive too...around $250 (25060-41G02).  If anyone has a source for this part used I would love to hear about it

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I had that guage on my 89, haven't thought of that in years.  I pulled a lot of parts off that truck, wish I saved the sending unit.  

 

I'm going to get the new one and find out.  Could benefit someone down the line.....

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Somewhat unrelated, Could you use larger fuel lines in an effort to increase performance? Obviously that means you'd have to possibly mess with the timing and such but just wondering. Not that I'm wanting to do it, just popped into my head

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The FSM procedure for checking fuel pressure has you hook up the gauge between the hose coming off the filter and what looks like the rail, so yeah, I'd say that's your high-pressure supply side.

 

13 hours ago, Wacky_Pathy said:

Somewhat unrelated, Could you use larger fuel lines in an effort to increase performance? Obviously that means you'd have to possibly mess with the timing and such but just wondering. Not that I'm wanting to do it, just popped into my head


The engine wouldn't notice. The fuel lines are not what limits fuel pressure to the engine. The fuel pressure regulator regulates fuel pressure in the injector rail and sends the excess back to the tank. And that's not limiting power, that's just making things easy for the computer so that however many milliseconds of injector pulse equals however much fuel injected into the intake manifold. IIRC the guys who've turbo'd these used higher flowing injectors and pumps to keep up with the increased fuel demand. I don't think the hard lines would become a limiting factor unless you were running the twin V8s from the Immortan's Gigahorse or a Boeing jet turbine or something.

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6 hours ago, Slartibartfast said:

The FSM procedure for checking fuel pressure has you hook up the gauge between the hose coming off the filter and what looks like the rail, so yeah, I'd say that's your high-pressure supply side.

 

Thanks, makes sense.

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On 11/24/2018 at 3:45 PM, Steve_RI said:

One of the outlets on the fuel tank sending unit snapped off at the base..part is friggen expensive too...around $250 (25060-41G02).  If anyone has a source for this part used I would love to hear about it

I found some pretty good deals at AM Auto Parts.  https://www.am-autoparts.com/

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Here is the comparison between the two units.  As you can see they are very similar, the old one being slightly longer with the float sitting lower.   Given that these go in the same gas tank with the same fuel pump the difference must be at the instrument cluster.  The old trucks have a horizontal gauge while the  newer trucks are vertical.  I think this should work fine and will probably be off an 1/8 of a tank or so.

 

viV6ZTz.jpg

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Well, this was a huge pain in the ass, especially in 25 degree temps, but I'm happy to report that the newer fuel sender works fine in the older Pathfinders.   I bent the copper lines as close as I could to the old ones, but it was still a pain.  I spliced in the new lines in right about at the spot where they make there straight run to the front after the rear wheel.  They looked pretty good running up to the front of the truck from there.  I'll report back after a trip when I can fill it up and see if it's off.   Fyi, If you are under the truck in the rear poking around, the high pressure line is the bottom one.

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They always seem to rust right where the frame turns down. That's where mine were rotted. I just ran rubber hose from the tank to that point. The rest of the lines were mint (literally looked new with the green coating).

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adamzan is the lucky one... my lines had already been off twice before I bought the truck and put back on with sheetmetal screws in a different place every time. But that's what you get when you buy a running project for $750 CAD. I was just thinking that you could maybe bend the steel rod that holds the float to get it down closer to the original height of the float.. but since you've already got 'er in there... nevermind!

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I was thinking of tweaking the float, but I just wanted the truck running.  It's still a possibility, but I really want to fill it up and run it down close to empty to get some  visual and measurable  results.

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  • 2 weeks later...

I would think that you'll get the top 12 gallons  of fuel and then have the fuel light on.... clearly you have the 21 gallon tank though. I would think a tweak to the rod would be the easiest thing to do. Close is close enough! That rod is stainless steel (IIRC) and should take to bending once or twice without trouble.

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  • 1 month later...

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