Gas dripping from exhaust?

[GNRichard]

Hi, new to the group, but I have been reading for a while and havent seen this one before. I have a stock '87 GN which we bought new. It has about 250K on the engine. Recently it started to smoke a little and give a real rich gas smell from the exhaust. It has now gotten to the point that idling, it sends out huge clouds of white smoke and starts dripping gas from the pipes. The only scan tool I have is WINALDL, I took a short run the other night to see if anything would show up but I am not sure of the readings I got. I have attached a PDF of that run. Any suggestions? Thanks!

[Ts86ttype]

Check your coolant level... It's most likely low. You probably have a head gasket going out and the coolant is mixing with the fuel, so coolant with a gas smell coming out the tail pipes... Tom G.

[GNRichard]

Coolant level is full and clean looking. Oil also looks good.

[Ts86ttype]

Is the coolant overflow tank full and the radiator full??? What you are describing really sound like a head gasket... Not all head gasket leaks go into the oil, but a lot sure show up in the exhaust system... Have you pulled the spark plugs and see what they look like??? Tom G.

[GNRichard]

The coolant tank ais at the normal level, the radiator is full. I pulled a couple of plugs the other day on the drivers side and both looked normal, but I haven't pulled all of them. Is that a likely place to go from here?

[Keller]

Perhaps an injector stuck open? Try disconnecting one injector at a time to check.

Still, doubt raw fuel would be dripping out the tailpipe.

[GNRichard]

OK, I'll try that after I check all the plugs.

[Ts86ttype]

Is your motor all stock, turbo too??? Tom G.

[GNRichard]

Yes, all stock except for the vacuum brake conversion. The only other major repair I have had is the timing chain and gear at about 200K.

[Ts86ttype]

Could it be you are seeing light blue/grey smoke from the tail pipes??? That still wouldn't explain the dripping, maybe some extra condensation from the pipes... Take a good look at your plugs and let us now what you see... Tom G.

[GNRichard]

Yeah, it could be a light blue. The main thing I notice is the gas smell is so strong that it burns your eyes. The liquid that drips out smells like gas, but feels a little oily. I will check the plugs tomorrow and let you know.

[GNRichard]

Well I pulled the plugs. All except #1 were carbon fouled, but they were'nt real bad. The #1 plug looked normal. I started it back up after I put them back in, but didn't have a chance to take it for a ride. The smoking was still there but a little lighter than before.

[Keller]

Paying any attention to your data? :hyper: Both the INT and BLM are stupid rich. Either your fuel pressure is through the roof, an injector is stuck open, its wiring is shorted, or the chip calibration and injector size do not match. :ow:

See http://www.gnttype.org/maint/quickref.html and http://www.gnttype.org/images/blmint.gif

[Ts86ttype]

What else have you done to your car in the 250K besides the timing gears??? Have you ever had your injectors cleaned or replaced with newer style stock ones??? What is your fuel system like, adjustable pressure reg or the original stock one??? Parts do wear out... Tom G.

[GNRichard]

The inectors and the regulator are stock, the regulator was replaced a few years ago, the injectors were last cleaned about a year ago but they are the original injectors. I know that the numbers show a rich condition, which was obvious from the smell I was getting. But I am not sure what to look at first. I am guessing that with the numbers reflecting what I am observing, that the sensors are OK? Would the O2 sensor have an affect on this since it relates to how much fuel is added or subtracted? or should I concentrate more on the fuel system?

[Ts86ttype]

GNRich, Yes the o2 sensor can effect it, but lets not through parts at your car... If you can get a fuel pressure gauge and see what your pressure actually is would be a good starting place...By the way, the pressure will be 24-36 lbs when you turn on the ing... Tom G.

[GNRichard]

The fuel pressure is about 35 when I turn on the ignition, and 38 when it is idling with the regulator vacuum off, 30 with the regulator vacuum on.

[Keller]

That is reasonable.

What chip is in the car?

[GNRichard]

The chip is the original.

[Keller]

OK. I would then check all of the injectors for one sticking open. If the fuel pressure holds after the car is turned off for a substantial amount of time (i.e. 30-60 minutes) then that is not an issue.

Next I would check the injector wiring. Perhaps one or more injectors are being held open by a shorted injector wire while the motor is runnning. that would definitely cause something like this. The injectors are fired by switched grounds, so a shorted wire is all that is needed to hold an injector open. A 'noid' light would also be a good tool to diagnose this. It plugs into an injector connector and flashes when the injector would be commanded to open.

http://www.amazon.com/gp/product/B0002SR4OA

Might be able to borrow one at a local auto parts retailer via their tool loaner program.

[GNRichard]

I checked with a noid light and #6 is staying open (solid light) the rest are all flashing as the car runs. I guess this means a short in the wiring somewhere for #6?:ugh: The pressure does leak down fairly quickly when the car is turned off also. How do I check for which injector is causing that issue?

[Ts86ttype]

The short to ground is what is keeping the injector # 6 open... Unplug the wiring to the injector # 6 and recheck the fuel pressure, it will probably not drop down as quickly... If it doesn't, then check the wiring from the injector to the connector under the ing. modual to see if it is grounding out... If you put the noid light on any of the injector wiring plugs with the key on, not running the light should be off... The ECM adds the ground to pulse the injector... If the noid light is on on #6 with the key on, then unplug the ECM and see if it goes out... If it goes out then ECM is bad, if it stays on the black wire with the yellow tracer is grounding out some were... Tom G.

[GNRichard]

Yes, you are correct.:tup: The light comes on when the key is turned on and stays on while the engine is running. When I unplug the ECM it stays on, so this will be a short somewhere in the ground to this injector?:lite: Also the fuel pressure does not drop as quickly, but still drops with #6 unplugged. Is there a likely spot to look for the short?:confused: According to the schematic I saw on the site the ground goes to the ECM where it is switched. Is there a connector in between somewhere where it might get corroded or is it a straight run of wire? Is it also possible for that one "switch" in the ECM to short out or go bad and cause this? Thanks for your help!!

[Ts86ttype]

GNRich, The injector harness connector is under neath the coil/modual... The plug in is a white connector... Check there... From the white connector it goes to the ECM as a Grey wire... Those wires go into the wiring harness that runs around the back of the engine, under the A/C box and into the passenger compartment to the ECM... You could put your noid light on #6 and with the key on move the wiring and see if the light goes out... Check the area that you disturb and see if you can find the problem... Tom G.

[Keller]

Injector wiring often is abraded right around the injector rail where it loops to plug into the injectors. Also. as it comes under the plenum and intake to the injectors. Fairly common with age and miles.

[GNRichard]

Well I am not sure where the short was, but after moving the harness around the light went out!:shiny: I am guessing since this is a common thing that the fix for this is to replace the harness? Is this part available or is there a better answer? Also, now that there is no longer a cloud of smoke from too much fuel, I can clearly see that the turbo is dripping oil onto the exhaust. Oh well, just something else to mess with! At least the gas is not dripping from the exhaust anymore. I will take it for a ride to the gas station tomorrow, almost out! Thanks again!:tup:

[Ts86ttype]

There is a harness for sale here in the FOR SALE LIST, or go here http://www.casperselectronics.com/store2/product_info.php?products_id=622 Tom G.