87 way too rich!!!

[loneranger6886]

1987 suburban 1500 4x4 TBI. Way too rich, dumping fuel into throttle body. Gradually getting worse. I have replace the O2 sensor, Map sensor, Coolant sensor, ECM, and investigating the EGR right now. Most of the replacements were from trouble codes or bad sensors in general. The strange part is that the injectors are both pumping out the same amount of gas. Way too much. When we disconnect the EGR it idles better, not much, but better. There is supposed to be 6 inches of vacuum there at idle but there is none. I cannot find any vacuum leaks. Not much left to replace, I am thinking its the Pressure Regulator but who knows. Any help would be much appreciated.

[2000CAYukon]

You need to find out what your fuel pressure is at. Unfortunately, there is no test port so you will need a tool that replaces the fuel filter. Once the tool is in place, you can attach a fuel pressure gauge to it.

TBI specs are 9 - 13 PSI.

//2000CAYukon

[loneranger6886]

I'll test it but i also replaced the fuel pump when we got the ruck, and the filter, ill go see what it says.

[2000CAYukon]

Originally Posted by loneranger6886

I'll test it but i also replaced the fuel pump when we got the ruck, and the filter, ill go see what it says.

For a rich condition, you want to make sure the pressure is not too high.

Looking at my 90 Factory Manuals, you need to check:

- Fuel Pressure Regulator
- Canister Purge (make sure no fuel in canister)
- Map Sensor (Also check for vacuum leak at the Map)
- TPS - A bad TPS can fuel the PCM to think the gas pedal is be pushed causing more fuel to be delivered.

//2000CAYukon

[wlryan]

Did you ever get your truck running right?
had similar troubles with my 87 - would not set any codes
found the coolant temp sensor was causing the IAC to stay open
try unplugging temp sensor connector and see if it smooths out.
another item would be to remove and clean IAC solenoid.
hope this helps

[loneranger6886]

Yeah i got it, shoulda posted a while ago when i did. Bent pushrod and valve. It was throwing everything off. Vaccuum, idle, my sanity. Runs like dream now, 15 mpg too!! check your valve train. I had a rocker pitched to the side and stuck on the pushrod and some nasty clicking when i put the stethoscope on the valve covers.