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ISX

Chasing Air Leaks

6 posts in this topic

I put this together today since it is probably the main problem 12v's face.

Air leaks can be hard to chase, especially with solid lines that you can't replace with clear rubber lines. You can but you have to buy fittings. All of the fuel from the lift pump to the injection pump should be at a pressure of ~26psi, so you can easily use clear hose in places to track air intrusions if you have all the right fittings.

Hoses can get hard, get cut, and crack which is the main purpose of using as much steel line as possible on the fuel system. Any fittings with copper washers may not be seating correctly and need new washers.

Some of the main things you want to check first are:

[*]Bleed screw on top of filter

[*]Fuel filter gasket and proper installation

[*]Fuel Heater gasket and housing (cracked)

[*]Hose clamps

If you have recently done something such as removing the return lines or taking off injection lines, you should double check all of those and make sure the washers on the return lines are in good shape.

When you have all the air out and are just trying to bleed it, you may also have to loosen an injector line. When you see fuel coming out, tighten it back down. If it is too tight when you are doing this, it will build very high pressures and spray all over the place, so loosen them maybe 1 revolution from being tight. Then you can crank the engine over while holding down on the pedal about 1/4 throttle and it will start up and try not to let it go over 1500RPM when it starts as this is not the greatest on an engine that has no oil pressure for the time being. Once it does start, keep it around 1200-1500 to keep it running and purge the remaining air out of the system. When it smooths out, it should idle smooth and your good to go. Check all your fittings to make sure they are not leaking fuel.

http-~~-//www.youtube.com/watch?v=u1C8e5Q1l2E

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Man you just the the youtube junky now... But I got to admit its a awesome write up on tracking air leak points and dealing with them. Hmmmm... I think they make a big line kit for the 12V p-pump... http://www.vulcanperformance.com/Draw-Straw-II-1-2-in-draw-tube-and-1-2-in-pushlo-p/12vfs.htm I have no idea what it even looks like... :shrug:

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It's a pita figuring out where each line goes whenever they all go under the intake manifold. Figured this has to help someone. I read about guys questioning where the lines go all the time. Never heard anyone talk about a big line kit for a 12v. I don't hear of many issues other than the seal on the fuel tank I replaced and then fuel filter and fuel heater issues.

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That also struck me as odd... That a old school 12V fuel system was good enough for bigger horsepower but even with the restrictions and banjo bolts etc it was fine... But on a 24V it was so bad most had ditch the stock fuel system and go big line kits... Really interesting... (Hmmm)

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That also struck me as odd... That a old school 12V fuel system was good enough for bigger horsepower but even with the restrictions and banjo bolts etc it was fine... But on a 24V it was so bad most had ditch the stock fuel system and go big line kits... Really interesting... (Hmmm)

I run higher pressures than you..

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This is a great writeup and even better video! :thumb1:Thank you!

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