Fuel problem?

[L8RH8R]

I have a 91 OBS that I removed a 4.6/5sp from. I installed a 2002 5.3/4L60E. I replaced the factory fuel pump with a new pump for a 2002 Silverado. Used high pressure braided lines both inlet and return. The stand alone harness was purchased from an excellent company on ebay and works great. VATS removed on PCM. After several cranks, the engine fired and ran fine for a minute or so before I shut it off (radiator not installed). Every time I try to start it now, it takes ten to fifteen cranks to start and I get a strong fuel smell not to mention lots of smoke from the exhaust. Trying to restart it after a short run in almost futile. I noticed the fuel pressure was a little low (30 psi at the Schrader valve) and I had quite a bit of fuel pressure drop after a run. I replaced the fuel pressure regulator, no change when trying to start it. I replaced the fuel injectors with Delphi remanufactured units, the pressure holds at about 40 psi with engine on and off. I checked the plugs and found all of them fouled with fuel. My suspicion is that the repeated attempts to start the engine is flooding the cylinders with fuel. And yes, my oil smells like gas. I've everywhere that the fuel pressure should be around 55-60. I checked my 2004 Tahoe and it runs consistently at 40 psi. I'm stumped. Oh yes, the crank position sensor has also been replaced. Sorry for the long post. Any help would be greatly appreciated.

[kewljay223]

low pressure could be caused by clogged filter or possibly pinched line. if you had a leak in a line, im sure you would see fuel everywhere so i doubt that. also, did you wire your fuel pump relay correctly? it might not be kicking on. or the relay went bad (which has happened to me before) this made me have to crank the engine forever, like your doing, before the oil pressure built up enough to kick on the pump. this is assuming your still using the oil pressure switch that came with the original motor. some guys delete it. i would start there. i would manually give the relay power to make sure it and the pump and the complete circuit is working. when i say circuit, i mean both the electrical circuit AND fuel circuit. you are correct in that you should have almost 60 psi, ESPECIALLY when the motor is not running. if your low when not running, you know your fuel circuit is clogged or open somewhere. this is assuming your using an accurate fuel gauge at the rails... idk how your getting your readings.

[L8RH8R]

Thanks for the quick response, definite things to look for. I am using a gauge I bought at autozone at the fuel rail. The filter is new and the lines are not pinched. The relay is wired correctly. You can hear the pump prime and then maintain pressure as the engine runs. What's interesting is my 2004 tahoe has the same pressure readings and runs great. An interesting development today though. I changed the oil which had a strong odor of gasoline. After the oil change, two cranks and the truck started right up and no more rich fuel smell. I'm going to purchase another fuel gauge to see if I get a different reading. I may switch to another pump.

[farmtruc]

Shit the truck off and pinch the return line.
If pressure drops the pump is bleeding off fuel and could be weak.

Get ur tahoe checked. It may "run fine" but probably has very high ltrims.
A stock truck will run fine on 40psi, but something ain't right

[L8RH8R]

So I installed a new Walbro 255 and nothing changed. The pressure rose just a little. 2 psi or so. I'm lost. The only thing I can think to add might be a hot wire kit. It starts about the same. Several tries before it fires up. While running it is smooth. When I idle it up, the pressure does come up a bit but nothing like the 55-60 psi I've heard about. The fuel filter is new. The fuel pump is wired off the original 1991 relay (red wire). And thoughts would be great.

[gagliano7]

What fuel system are you plumbed for return style or returnless? What kind of regulator are you running? I had my hose come loose on pump in my tank and only had 20 psi and motor still ran fine at idle and part throttle. I wonder if one of your injectors are staying open or one of your coils aren't firing. Is the PCM tuned for the injectors you have? I have the returnless setup with the corvette filter/regulator and I have 58 psi all the time.

[L8RH8R]

It's a return style. All factory, regulator and all. The hose on the fuel pump has a good connection (worm style clamp). The PCM is all stock. The only thing non stock is the shorty headers.

[Skylark]

I would try another gauge before I went further.

[L8RH8R]

I guess a starting point may be the factory wire I'm connected to. From the 2002 PCM grn/wht wire, I connected to the red wire coming off the fuel pump relay on the firewall of my 1991. Does this sound correct. Of the four wires coming off the relay, it's the only one that will allow the truck to run when it does start. Again, thanks for all the input. The hard start/ no start condition persists. Ughhhhhh.

[Skylark]

If the relay is sending power to the fuel pump then it is working. What you need to do if you're concerned about electrical issues, is to get down there at the pump harness self and check for a full 12 volts+ at the positive connector and do an ohms check on the ground side to verify that you don't have resistance.
I would still be leery of that fuel pump pressure tester that you are using. Two vehicles showing low is a red flag for me.