Engine/Transmission (1998.5 - 2002) Is a pressurized fuel tank normal?- PLEAE HELP!

[Hohn]

The other thing I was thinking was this:



Those injector holes are REALLY small. Under compression pressure, it would take a LONG time to move enough air to pressurize the tank, especially assuming only one injector is leaking or bad.



But MY tank will pressurize in as little as 2-3 minutes. After running just briefly, I can hear the hissing of the vent tube trying to bleed off pressure as the engine runs. It's just hard to think that an injector could possibly leak that badly, let alone leak that badly and still have the engine run smoothly.



So where else could the air pressure be coming from? I am pretty sure I didn't accidentally plumb my boost gauge line into the fuel return Ditto for my tires



So what's a guy to do? I installed some Mach 1's in another fella's truck today and they are awesome. The Mach 1s feel every bit as strong as my DD2s. Best of all, almost NO off-boost smoke, even at 6000 feet. The install went smoothly, and there are NO starting issues. I am a little jealous.



My starting issues have been going on for over 2 months now, and it's getting very frustrating. I can't figure out what caused this!! I mean, it went from starting PERFECTLY on the first try to NEVER starting on the first try (at least after it has sat). And it did this in the middle of a tank of fuel, so it wasn't a fuel issue. I changed the filter and it seemed to go away until my wife did a gasser start to my truck (no intake heating) when it was ice cold in the morning. The truck shook violently and spat HUGE clouds of white smoke. Only after shutting it down and restarting did it run properly.



It hasn't started properly since then. Ever since, I have to do the dance where I bump the starter, let the LP run, and only THEN will it start (given a little cranking).



I am worried that all this extra starter cranking is hard on my engine and especially the starter.



Justin

 

[15w40]

This is just a guess but the only source of air has to be from the cylinders. Is it possible that one of the copper shims located under the injector is leaking air? This could happen if it is scored or if the injector hold down bolt is not torqued correctly at 89 1n. Lbs.



When the piston comes up to TDC the compressed air may bleed around the copper shim and get back to the tank through the fuel return hose.

 

[Hohn]

I am under the impression that if the copper shim leaked, the only resul would be oil getting burned and/or compression leakage. How exactly can air get from the cylinder to the fuel return line WITHOUT GOING THROUGH THE INJECTOR?



Is this true? Is there a way for air to get to the return system without going THROUGH the injector?



When we did the injector install today in Gary's truck, I didn't see any possible means of compression air going around the copper shim and into the fuel return. If the copper is leaking, then it vents to the crankcase, NOT to the fuel return, at least as I understand it.



Can anyone shed light upon this matter?





Justin

 

[Gary - K7GLD]

I read something about a leaking injector line passing fuel to the crankcase in another thread - I've not seen that area close-up, and it's hard for me to visualize...

 

[Hohn]

Leaking fuel into the crankcase is no mystery to me. If fuel were leaking, it would be easier to trace. (injector connector tube, most likely)



What baffles me is how AIR can get in there! Air to the tank-- where from??



Justin

 

[A Johnson]

The compression comes from a faulty copper shim/sealing washer whatever you want to call it. The copper may be defective, or when you did the injector install a little piece of debris was stuck under it and finally worked loose leaving your injector with a loose torque on the hold down screws. I'm not sure exactlt what happens, only that once in a while they will leak. On the 12 valve mechanical engines it would be a leak of compression coming around the injector and venting to the atmosphere. On a 24 valve it would leak compression into the fuel return galley. The copper seals compression from the fuel return and return fuel from going in the cylinder. The injector O/R seals the top side of the fuel return galley, your injector is surrounded by return fuel.



A Johnson



On Edit: If you had a defective injector allowing compression into the injector, the air could possibly go backward to the VP-44, causing missfire, no starts etc, this also happened once in a while on the mechanical engines, especially if the mechanic wasn't careful of keeping dirt out of the fuel system during a repair.