Gas coming out of TailPipe

Information on the naturally-aspirated KA24E and KA24DE engines.
Graphfixz
Posts: 1697
Joined: Sun Jun 08, 2003 3:43 am
Car: Black 91 240SX Hatch
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Can the FPR be the cause of fuel coming out of the tailpipe? Lots and Lots of fuel... I don't mean a drop here and there, I mean where the back of the car (the drive way) has this streak of gas that is about 2 yards and a nice little puddle underneath the tailpipe.

FPR? Open Injector(s)?
Modified by Graphfixz at 7:02 AM 7/11/2009


liquid_cool
Posts: 1700
Joined: Sat Jul 05, 2008 3:02 am
Car: 1990 240sx ka24de-T swap 8.6:1cr ,duelsprings ,ti retainers,supertech pistons,K1 H-beems balanced internals ect ect.

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holy hell man!..that would be multiple injectors screemin wide open fuel dump!..does it even run like that?

dllkbales1
Posts: 12
Joined: Sun Jul 05, 2009 4:44 am

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The only time I saw a car push a large amount of gas out of the tailpipe it had an injector stuck wide open. It came out as a white vapor that smelled so much like fuel I thought I could have lite it with a match. From a distance you would have thought that it blew a head gasket except the smell. You just about could not see the car behind you it was that bad. I never saw it come out in a liquid. Pushing enough fuel through to exit as liquid could fill a cyclinder full and lock the engine solid on compression stroke. If that happens unplug the ignition, pull the spark plugs to let the fuel out and see which cyclinder has the issue. Make sure the igintion is inplugged from power, you dont want a spark with the fuel blowing out a cyclinder under your hood. Attempting to force the engine over with the cyclinder locked with fuel could bend a conecting rod. Are you sure its fuel exiting the exhaust? Does it run, does it run on all cyclinders, what color is the exhaust when it runs, any check engine lite on? If the system has a fuel pressure regulator on the fuel rail, unplug the vacuum line running to it, is fuel leaking thru the regulator and being burn thru the vacuum line? (this would not be enought to exit the exhaust as liqiud) Did you know that ever gallon of gas burned exits as on gallon of steam, a cold exaust system could exit condensed vapor as water. Dave

Graphfixz
Posts: 1697
Joined: Sun Jun 08, 2003 3:43 am
Car: Black 91 240SX Hatch
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you are correct. It started with white smoke which is why everybody was pointing me towards the head gasket thing.

However, it smelled like gas. So yesterday I went back took out the fuel rail, reseated the bushings and the injectors. The car does idle but instead of smoke, now it throws gas... lots and lots of gas.

so if it is an injector or injectors that are wide open, how does one close them?

Thanks for your help and quick response.

dllkbales1
Posts: 12
Joined: Sun Jul 05, 2009 4:44 am

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When you turn on the key, the fuel pump will automatically cycle to build pressure for the start-up. Pull the injector rail up out of the intake, leaving the injectors firmly in the fuel rail. They may even have clips that lock them into the rail, make sure they are all seated and locked into the rail. Unplug the electrical harness' from each injectoer so they con not be turned on by the computor, all of them. Hold the rail up a few inchs and have someone turn the key on, DO NOT CRANK THE ENGINE JUST TURN THE KEY TO THE ON POSITION. The pump should cycle, and you should build pressure. The injectors should all be closed and nothing should spray, no a drip. Any that do need to be replaced. You can not repair them, the issue is internal and if you were to free them somehow you will have the same problem at a later date. If none spray turn off the key, hook back up all the harness connections. Again hold the rail and turn the key to the ON position. If any cycle now, the computor or the wire harness is turning them on. The harness should have power to all injectors on one wire at each injector plug. Key on and the harness off then injector you should see this with a test light on one of the wires. The second wire is grounded by the computer when the spray in required. Either you have a bad computer and that injector driver is stuck on or the wire that grounds the malfuntioning injector has rubbed thru and grounded itself between the injector and the computor. The current is coming thru the power lead, thru the injector, and finding an improper ground before it gets back to the computer. Now is when you become a real tech. If you see the color of the wires at the bad injector, and see which one has power when unplugged, you will know that the other wire is grounged by the computer to run that injector. If you go find that exact wire at the computer ( use wire schematics to get the correct pin position and recheck the color) you can cut the wire a few inches from the computer, if the injector still sprays, its the harness wire grounding out when the key is on and you have to find the bad spot. If the injector no longer sprays then the computer was turning it on all the time and the internal driver for that injector is the issue. The cut wire MUST be soldierd back together and shrink-wraped. Wire nuts, crimp connectors, and tape are all BS on a computer harness and will fail. The slightest resistance in the wire will effect operation. Its a lot to take in, hope you got it all. Dave

Graphfixz
Posts: 1697
Joined: Sun Jun 08, 2003 3:43 am
Car: Black 91 240SX Hatch
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ok, so for closure, I had to take my car to the mechanic. He found an injector that was fully opened (#3). He also found a leak on the hose that went straight to the FPR. So although the FPR was working, it could not maintain the pressure because of the bad hose.

The important thing here to remember is that when this happens, you are getting a lot of gas through the system. The mechanic found the engine full of gas. So he had to change the oil twice before it got semi cleared. I am responsible for the 3rd change in a few days.

Thanks for all your help guys!!


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