I had the split fuel hose in my last chevy tbi. I found that before replacing any parts because a simple fuel pressure test revealed it. later blew the ecm 10 fuse with a bad oil pressure sending unit and then again with a short on the back of engine from the loom wearing out. other than that, it was a fairly reliable although neutered 350.
In this case I have a wide mouth portable can with a total of about 8 feet (including return) of flexible 3/8 fuel line going to a brand new ac-delco fuel pump with brand new stock strainer. A clear paper filter is between the pump and the throttle body. The fuel was pumped from a shell station hours before running it.
Checked the TPS. Throttle closed: .55V WOT 4.26V
MAP sensor: 4.3 v (new and old one) with no vacuum pulled. Voltage decreased with vacuum down to less than 1V with about 25 inches hg.
Didn't have time to test the EGR other than unplugging the line to the diaphragm. I don't see how it could make it run this rich.
Codes : #12 only!. This after running it about 10 minutes and playing with different things such has vacuum level on the MAP and fuel pressure. It would barely move when put in gear. The IAC does move in and out with changing throttle position and vacuum. The IAC was making noises while I was checking the codes. With about 15 inches hg pulled on the MAP I was able to run the fuel pressure down to about 3 psi and it actually ran better (even while opening the throttle some). I tried higher pressures too (up past 15psi). It would stall out at that pressure unless I had over 20 inches hg pulled on the MAP.
The injectors are new and put out a conical pattern although it is mostly small droplets rather than a foggy appearance like how I am used to seeing with higher pressure port injectors (or carburetors). I don't understand what would make it run so rich as to run better at 3psi fuel pressure than 11psi. I suppose there must be some fundamental things about this system that I do not understand. I have spent a good deal of time reading forums and have not found this set of symptoms. I do need to spend more time combing through all the electrical parts.
Could the ref from the distributor cause this? Haven't checked that yet.
