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Discussion Starter · #1 ·
So I changed the hose on the fuel return line few days ago because it was leaking. I started the truck, it worked for few minutes then died like it run out of fuel, but it has a lot of fuel in the tank. I unscrewed the overflow valve a little bit on the injection pump and started to pump the fuel manually with the button that's on the mechanical lift pump, and I saw bubbles coming out of loosened return line.
My question is where it could suck air from?
I also happened few months before when I was driving and it died on the road, pulled off and started again with about 10 seconds of cranking.
I though it might be bad fuel sending unit that I replaced from another truck? I think it's in good condition.
Could be a problem with an injection pump? Any seals that I have to change?
:confused013:
 

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There are several places for an air leak. Email me at [email protected] for the current version of my 12 valve fuel supply system write up, how it works and how to fix it.
 

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I've found that in the struggle to replace the return hose behind the engine that the metal line on top of the bell housing easily gets cracked.
That's one reason I no longer replace just the short hose but instead abandon the stock fuel supply/return lines all the way from the engine to the tank and replace with hose.
A permanent fix if you use high quality diesel hose.
 

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Discussion Starter · #5 ·
illflem:

That's a good idea. I might have to also replace them all with a good hose.
After I put the short hose I noticed that it has lettering on it, something like that "Not to be used for fuel injection" lol. So I guess it won't hold on for long.
 

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First of all, don't go thinking it's the IP from the start, it's the absolute least likely thing to be the problem. Double check all of your connections, and replace all rubber fuel lines with some high quality stuff, especially since you said that it has happened in the past too.

There is also a short rubber line from the tank unit to the hard line running along the frame, these things eventually crack especially at the ends where the clamps are, and air can eventually escape past these points (on all lines, that is).

As for the "Not for fuel injection systems" hose (J30R7), that just means it's not meant for a pressurized fuel system, and since on the cummins motor configuration all of the rubber hoses are pre-lift pump, there is no pressure, and therefore no reason to use pressure-rated hose (J30R9).

Hope this helps,
Nick
 

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Discussion Starter · #8 ·
I finally found a huge air leak. First I fixed my old sending unit and put it in, now my fuel level gauge works, :party018:. Then I removed the fuel heater, just in case. Then I noticed that the nut that holds the steel fuel line on top of the pre-filter was very loose, so I tightened it, then I started the engine and it idled for about 30 minutes non-stop. Yeah, super.
:headbang:
 
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