95 blazer rich idle in closed loop fuel

Need help. Start fine in cold weather difficult to start when above 30 degrees. Starts fine while engine still hot. Idles rough. Have had EGR valve replaced. Scanner shows .8 to .9 volts on 02 sensor 1 (rich) at idle. Fuel pressure ok and manifold pressure sensor appears ok.. Is there any way to test the cmfi unit to see if it is causing the rich at idle problem.

When you check your fuel pressure, turn the engine off and watch. Does the fuel pressure drop? If so, you have a leak. Most commen injection unit, regulator, or fuel feed lines inside manifold.

Need help. Start fine in cold weather difficult to start when above 30 degrees. Starts fine while engine still hot. Idles rough. Have had EGR valve replaced. Scanner shows .8 to .9 volts on 02 sensor 1 (rich) at idle. Fuel pressure ok and manifold pressure sensor appears ok.. Is there any way to test the cmfi unit to see if it is causing the rich at idle problem.

Fuel pressure is ok?

What is the fuel pressure?

When you check your fuel pressure, turn the engine off and watch. Does the fuel pressure drop? If so, you have a leak. Most commen injection unit, regulator, or fuel feed lines inside manifold.


Thanks for the help. Fuel pressure dropped when engine off. When I inspected I found the fuel inlet tube had been rubbing on one of the injector tubes and had worn a pinhole in it. Replaced the fuel inlet tube and now runs fine. Thanks again.

Thanks for the help. Fuel pressure dropped when engine off. When I inspected I found the fuel inlet tube had been rubbing on one of the injector tubes and had worn a pinhole in it. Replaced the fuel inlet tube and now runs fine. Thanks again.

So, you changed the nut kit?

Make sure you change the oil ASAP.