Exhaust smelling strongly of fuel

[bix]

Hi all im new here and im glad to be here.

I have a 1990 K5 scottsdale and i cannot find out why my exhaust smells strongly of fuel. I have replaced the injectors, serviced the TBI with a throttle body spacer, replaced the regulator spring and diaphragm and all gaskets. The injectors seems to spraying fine. I have checked the usual's in my haynes manual emissions section. the EGR valve is moving with slight pressure as it should and the PCV valve seems to be working, In the book it says there should be vacuum but it seems to be blowing air instead if thats okay???. Im new to the city im in and i do not know the community i used to.
It also idles a bit low at first start up when cold and then picks up and few times and works itself out. im assuming this could be a part of the issue. Any information would be awesome if anyone has had this issue before.

Thanks again

1990 k5 350 sm465trans 240k km

 

[bix]

could this be my map sensor unit or another sensor possibly?

 

[Greg72]

Welcome to CK5!

I'm sure you will eventually get an answer to your question.... For sure, "The Garage" is the most active of all the forum and gets the most views. If you don't get an answer in this sub-forum you can post this same question there...

Good luck.

-G

 

[bix]

It is running rich in both banks according to my plugs. i have checked voltage for my ECT sensor my MAP sensor and the throttle possisioning and it all has voltage, how can i check the sensors themselves besides buying new ones and seeing if it changes anything? I will do that if needed just wondering if anyone has any ideas before i start buying things i might not need

thanks

 

[bix]

I changed my MAP sensor and ECT sensor and still no change? Can anyone PLEASE give me any ideas as im not in any way a mechanic..

 

[Greg72]

I can move this thread to the garage if you want.... You'll get more views and probably more help too.

Let me know if you're interested.

-G

 

[bix]

How do i delete it?

 

[Blue85]

Do you have an ALDL cable where you can get data? You want to see the O2 voltages. Does TBI list fuel trims? You can sort of bench test an O2 sensor with a propane torch, but it only tells you if it works or not, not quick or accurate it still is. Any trouble codes or SES lamp? What is the fuel pressure?

 

[bix]

No i dont have one that hooks up to a computer and havent found a program for mac yet. No ses light and no codes. Its not going into closed loop in idle so im not sure what the o2 sensors doing. Ive been on night shifts lately and will be on another 20 days and winters xoming soon, so i havent been to active on it. How do u test the o2 with a propane torch. I have a tiger torch laying around

 

[Blue85]

I don't know if you have a 1-wire, 2-wire or 4 wire sensor. You can find the heater wires on a 4-wire with an ohmmeter. Then you want the other wires for the signal. If you have a 4-wire, make sure it is getting power - a bad fuse can cause your problems. I was thinking that TBI trucks use 1-wire sensors, though, which makes finding the right wire pretty easy.

At any rate, you test from the signal wire to the ground wire or the case with a DMM (volts). Heat the sensor with the flame until it starts to produce a voltage. Then wave the flame on and off the tip. The voltage should change quickly as you move the torch, getting up around 1/2-volt or more.


If you can figure out a way to tap into the O2 sensor wire you can measure voltage while the engine is running. If it is rich and the sensor works, it will be at 0.7-1.0V. If it's lean, the voltage will be 0.2-0.4V. If the system is in closed loop, the voltage will continually dance high and low. How do you know it's not going into closed loop?

 

[bix]

Thanks alot i am going to try that! And i read on a gm site that if u place your paperclip in the a and b terminals with it running and the light flashes 2.5 times a second it is in open loop and if it flashes once a second its in closed loop. If i rev it up to about 1500 rpms it foes into closed loop and then as it goes back to idle (500) rpm it starts flashing fast again as if its in open loop. I have just received a new sensor wire. So i am going to replace the wire to the ecm to be 100% sure and then see if it changes. Im also going to order a heated o2 sensor due to the fact we have very cold weather here at times and maybe thatll help. The engine is running a 195 thermostat and is opening and closing properly.

 

[bix]

The reason for the new wire is that i was told it may go into closed loop because of the rpms anyway and the sensor could still be at fault. It was 20 bucks for the new wire and thought why not. This is a long term project so new parts cant hurt