I have a '98 SH that threw a code 1072 - running rich. I watched the short term and long term fuel trims and they are running about -14%, so it is definitely running rich.

I've been through almost everything that can cause this and have found the fuel pressure is running about 50 psi. It runs about the same whether the vacuum line is connected to the FPR or not. The high range of the spec (according to Mitchell) is 37 psi.

I removed the return line from the FPR and put a long hose on it and ran it to a bucket. While doing this the fuel pressure stayed at 50, so I believe that rules out a blockage in the return.


I don't see how the high pressure could be explained by anything but a bad FPR.

 

Sounds about right. There is nothing else in the system that regulates pressure.

 

Pull the vacuum hose off the fuel pressure regulator if you want to find out for sure. Should be no fuel present.

 

I installed a new fuel pressure regulator and my pressure is still 50 psi!

What is going on? I've never seen this before.

 

Bump for my headache.


Out of curiosity, what should my MAP read at idle? I'm in Tucson, Arizona, which is pretty close to sea level I believe.

 

Try a different fuel pressure gauge.

 

Bingo.

I've been using the same gauge for a long time with no problems, but apparently it just crapped on me.

I tried another gauge and it showed normal pressure. I tried both gauges on another car that I knew had good pressure and it confirmed that the first one I used was reading high.

I noticed when I turn the key on (not running) the pressure will drop fairly quick. If I pinch the fuel line just above the filter (I'm reading pressure at the filter), the pressure holds.

So, apparently I have a fuel leak at the injectors. This would explain the running rich.

I'm going to try pulling the fuel rail up and pressurizing the pump. Hopefully I'll see which injector(s) is leaking.

 

Try pulling the plugs. See which one is super black.