Engine/Transmission (1994 - 1998) air leak

[wrichards]

I am getting an air leak somewhere in my 1996 12 valve. If I open the bleeder on the top of the filter and pump away I can finally get the truck going. Runs for 2 minsutes normal than dies. bleed again and starts up with same dieing out in 2 minutes or so. Where are some common places to check first? Oh and when the truck si running if I open the filter drain lots of pressure coming out.

 

[yenga80]

I would check your rubber fuel return and supply hoses located under and behind the fuel filter. I changed mine makes a world of difference. One of them was larger diameter than the other. I think Larry B's sells them. I just bought mine at a local marine shop diesel rated hose.

 

[hsmith]

^^^^
These hoses will allow air in but not show any fuel leakage. Another common leak is the fuel heater.

 

[GAmes]

Here is how the fuel system works and how to trouble shoot it.

http://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html

 

[KBurgoyne]

ahhhh the good old air leak. if it makes you feel better, my truck was stuck in the garage for two weeks while i was hunting one down. in order of ease to check, fuel filter (sometimes they shake loose), fuel heater, WIF sensor (bad washer or leaking spout), fuel lines, short rubber elbow between lift pump and water separator, metal elbow fitting to lift pump, metal fittings into lift pump and water separator. if you end up having to remove things take a compressor and plug it into the rubber supply hose and clamp off the return; cardboard and vicegrips work fine, pressurize the system at 15psi, listen for leaks and look for bubbles. i believe the compressor idea was GAmes' advice to me, and it works, so all credit to him or whoever it was.

 

[hsmith]

Gary definitely has been there-done that times before. Unlike me, he also can remember most of the fixes!!

 

[LNaugle]

A quick at home method, with compressed air, is to stuff bunch of rags in fuel filler,not down into it mind you, and take a blow nozzle and squeeze it into the filler and pressurize the tank. Dont get out of control here, just need some pressure, and have someone inspect the lines and fittings. If you have a leak, this usually makes it appear... . Also good for priming if fuel system is good... The most common thing i have found is where the fuel lines go through a retainer, at the back of motor drivers side, lines vibrate on retainer and wear through... . deffinetly not the only place that can have a problem, just more common in our area...

 

[PToombs]

Unplug the wire going into the fuel heater when you pressurize the tank. Mine was leaking there and it didn't show until I unplugged it and the fuel poured out.