Perhaps Too Much Fuel Pressure?

[88blazerboy]

I still have, for the most part, a stock 5.3 from a 2008 Tahoe in my 88 K5 Blazer, so we're talking 330 to 350hp at most. I do have some JBA headers that give it a little more, but not much.

Anyway, I have a pump I bought from Summit that dropped into the Blazer's stock sending unit fine, and I've been running it for about 7 months now. It puts out 90 psi, and I've always noticed that the truck is running rich. I think this is bad (Disclaimer: I'm not a professional mechanic!)

Is 90 psi for my setup too much? Can/will this cause problems, and if so, what?

[Skylark]

What is the fuel pressure at the rail? The regulator should kick it down where it belongs unless the pump is just flat over coming the regulator.

[88blazerboy]

Pressure at the rail:

(key turned but engine not started is 55psi)
(Engine started is 90psi)

[GMCwantsLS1]

60 is about right. 90 is too high.

[88blazerboy]

Thanks! Looks like I'll be dropping the tank again here shortly.

[foggy]

Are you using a fuel pressure regulator?

[GotaluvHP]

Too much pressure unless you're running a lot more HP than stock. I don't know what harm it would do other than run rich and throw o2 errors.

[88blazerboy]

Are you using a fuel pressure regulator?

Yes. Got a corvette/wix regulator hooked in shortly after leaving the tank. The rail on my motor doesn't have one built in - some didn't in 2008.

[88blazerboy]

Too much pressure unless you're running a lot more HP than stock. I don't know what harm it would do other than run rich and throw o2 errors.

That explains the engine running rich - no codes tripping, though.

[foggy]

Yes. Got a corvette/wix regulator hooked in shortly after leaving the tank. The rail on my motor doesn't have one built in - some didn't in 2008.

I would think that you have a bad regulator than. It should regulate it to about 60 psi.
How is your fuel system set up?