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AutobotWrangler 09-18-2013 04:12 PM

fuel out the tailpipe!!
i been having fuel and white smoke coming out of the tailpipe. I did an oil change, looked like there was gas mixed with the oil and the oil prob had two quarts more in it than it should have. i replaced the spark plugs, wires, cap and rotor. Coolant looks clean. no leaks in and around the engine. i replaced the throttle positioning sensor and air temperature sensor. gauges are working and pressure looks good.

CEL came on and it read 15, 24, 27, 33.

I wiggled the distance sensor and that turned off the #15.

24 was the throttle positioning sensor and when i replaced it, that shut off.

33 is the AC clutch relay but i dont have AC in my jeep because its a 91 so thats exempt.

The problem is 27 which is the tbi injector does not respond properly. Im guessing this is the first injector that made this appear. Hopefully i can replace this injector and that will fix the problem with the fuel out the tailpipe.

Has anyone ever had this problem before? Or know if im doing something wrong and can lead me in the right direction?

some people have told me that it could be the head gasket or exhaust manifold gasket, or valves but if that was the case, shouldnt it be leaking coolant into the exhaust, not gas?

western196611 09-18-2013 04:22 PM

White smoke usually means water/antifreeze. And it could be a small enough amount that it dissipates before running out because of the temp of your exhaust. I would guess you are leaking water into one cylinder and it had fouled your plug and that is where the fuel is coming from. Is your engine missing out?

jokerchief462 09-18-2013 05:03 PM

Is the white smoke constant or does it go away after a while?

CMike357 09-18-2013 05:57 PM

Code 27 is Fuel Injector control. 91 YJ with 4.0L has MPI not TBI. When you changed the plugs did one of them look different than the others? Fouled as opposed to clean, or wet as opposed to dry. If so that is the first place I would look. Are you sure that it is fuel coming out the tailpipe and that it was fuel in your oil and not water. What color was the oil when you changed it? If it was milky I would lean toward water getting in via a blown head gasket. First thing I would do is a cylinder pressure test, that should narrow it down to which cylinder your having problems with or the location to look for a head gasket problem. Thats where I would start anyway. Keep us updated on what you find.

Mr.Mud 09-18-2013 09:03 PM

fuel pressure test and compression test.

AutobotWrangler 09-18-2013 10:07 PM


I replaced the first injector because it wasn't reading with the ohm meter hooked up to it.

Got the new one and tested it and it read 19, which was 2 more than the rest which were 17. I then started the jeep and it was still pushing white smoke and liquid was coming out the tailpipe, but it didnt seem like fuel, more like condensation mixed with a little fuel. Eventually i revved the engine a few times and decided that taking it for a spin around the block would help me see if it got better or worse.

halfway it started smoking from the exhaust and engine so i drove right back home. I left it idling for about 10 min and eventually the smoke cleared and no fuel was leaking/ spitting from the tailpipe.

In conclusion:

I went through a full tune up, spark plugs, wires, cap and rotor, throttle positioning sensor, air temperature sensor, and an oil change, and finally a fuel injector.

Looks like the bad fuel injector was the reason it was letting the fuel into the exhaust because it was probably stuck open.

Hopefully no other problems arise but i will keep everyone posted. As far as i know, there could be some crap in the cat converter and muffler which will probably need to be replaced soon. Right now im a happy jeeper and learned a few more things about the jeep i just bought.

Thanks for all the support! Friend me and keep in touch.

western196611 09-19-2013 05:41 AM

Glad to hear you're on the way to success!

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