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Discussion Starter #1
Hey guys... when trying to start my car... a ton of fuel leaks out of the exhaust manifold... someone told me its probably an exhaust valve stuck open... the engine has less than 70k miles on it... Another thing that is weird... is that i get 150psi in each cylinder... so the compression is good... the timing is on... what else would cause fuel to leak out of the exhaust manifold??? and, if infact the exhaust valve was stuck open... wouldn't i get a bad compression reading??? thanks for all your help in advance... karma for all help. oh... and P.S. i thought it would be an injector stuck wide open... but i switched fuel rails... and still the same problem. 93 mx6... 6 cyl ls.
 

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Perhaps you have a fuel leak in the fuel supply or return lines, I don't think it's possible for you to see fuel leaking out of the manifold and there not be a massive exhaust leak.

So, check the fuel lines themselves, it's probably dripping on the exhaust and running down the outside.
 

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I believe that there is one specific hose that runs between the intake manifold that often times goes bad. Sorry I vaguely remember it while flipping through my haynes. If you have a haynes manual give that a lookover if not wait for me to check it out again. But basically yes what snailman said.

metros
 

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Discussion Starter #4 (Edited)
cool, karma for both of you guys... if you can find out exactly what it is i would love you both forever.. =) thanks a ton i will start my search.. Also... someone mentioned fuel pressure regulator... could it have anything to do with that???
 

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CincyMX6 said:
I also have a remote start... Do you guys think that could be a problem???
as the other guys stated, its probaly a hose leak.

did you replace or check the rubber fuel hoses when you swapped the injectors?


where exactly is the fuel leaking? on the outside of the motor or internally? Its kind hard to make an accurate guess at your problem with your description.

The fuel pressure regulator could be the problem IF, its leakin around the seal, or cracked.

It could also be around the banjo bolt if it wasent tighten enough or if you used the old washers.


If you need hoses, i actually have a good used stock pair.
 

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Discussion Starter #7
its actually leaking internally... im sure its not leaking outside and dripping... what would cause fuel to leak into the exhaust manifold??
 

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what would cause gas in the exhaust?

A cylinder not fireing. If there is no combustion (if the gas is not ignited) in one of the cylinders, you would just have gas and air being pulled into the cylinder and pushed back out through the exhaust valves.

But this would mean your motor would run terrible.. you would notice a big difference, it wouldnt even sound right.
The solution to that probelm lies in the ignition.. spark plugs, wires, distributer.

The only way fuel could leak internally into the exhaust, would mean its not being ignited.

But even IF this was your problem, you wouldnt be asking about fuel in the exhaust manifold, you would be asking why does my motor run rought and stall.


first off, how can you tell that fuel is leaking into the exhaust manifold? do you have the exhaust pipes removed from it? And since you have an LS, the V6 has 2 exhaust manifolds....
are you sure your not explaining this wrong?
 

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Discussion Starter #9
my car does not start... It just cranks and cranks and cranks... its in the front manifold. the downpipe was only bolted on by 2 bolts instead of 3... whenever it cranks i can see a steady line of fuel pour out... I have replaced the disty cap and rotor, plugs, wires... crank shaft position sensor... the ECU.... I'm explaining this correctly... I have never heard of this problem either.
 

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no spark.

its cranking and cranking, but nothing is igniting the fuel... although i would definitely be clearer with the descriptuion.. you make it sound like a garden hose worth of fuel..

anyways the ONLY way, with good compression (well, kinda good - more on that later) you can be dumping that much fuel into the exhaust ports is b/c nothing ignited it.

pull your plug - i bet they are fouled since there wasnt any spark.. after that its tracing back through the ignition to fuind the culprit.. likely a dead ignitor in the disty.

back to compression. while i dont think its your problem, i've seen cars with a physical HOLE in the cylinder wall still produce compression readings that would at least indicate a running engine.. the hole would be in the lower portion of the chamber, and since compression checks only check the peak value, that part is quite literally ignored, and once the piston gets to a sealable piece of the chamber, starts compressing the air inside...

a leakdown would diagnose this issue. but again, i don't think that's the problem.. i think there is something just physically not sparking and burning any of that fuel.
 

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Discussion Starter #12
you are probably right, goat... I have replaced most everything... wires, plugs, disty... crank shaft position sensor, and ECU... Guess i'll have to bite the bullet and buy another engine to drop in... anyone know of any good websites that sell engines?
 

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wait wait wait.. lol

have a leakdown done first - cheaper than a new engine.

also- i've seen a remanufactured disty have a bad ignitor out of the box - eliminate that as a problem first.. just test for spark - have someone crank while you hold a plug (attached to wire) between a screwdriver and the manifold and look for the arc.

also - as silly as this sounds, double check everything you did... its easy to lose track of stuff and leave a plug loose, etc.

i don't think a new engine is the answer until you've figured out the problem... sounds like a spark problem to me.. not an engine failure... (in which casde a new engine won't start either, if the same spark problem persists.
 

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Discussion Starter #14 (Edited)
I've got spark... that isn't the problem... I had spark with my old disty aswell... I even put new cap and rotor on... still nothin... What I think is happening is that the injectors are firing even on the exhaust stroke... what would cause that???
 
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