Loc: Eastern NC
03-03-12 09:38 AM - Post#2197908
In response to Chevytech
I don’t have a 1992 manual handy so I looked it up in a 1993 manual for a 2.8 Liter with a manual transmission.
The desired idle speed is 800 RPM plus or minus 100 RPM, at sea level, fully warmed up, in closed loop, with all accessories off.
Anything out of the normal range, like a low charging voltage may cause the system to raise the idle speed.
It is within the acceptable range.
Thanks for the specs Chevytech.
I did replace the alternator from another truck but didn't see a difference in idle but will keep that in mind.
As for the surge:
You could disconnect and plug the EGR hose, and take it for a test drive.
I've been driving it with the hose plugged and it does run better. Does that mean the egr valve is bad or does it have a bad egr control or circuit? It seems that if the valve were bad it would still leak and cause it to run bad with the hose plugged? Don't know.
Testing the fuel pressure would be a good idea too. Just because you replaced the pump does not mean the pressure is good. There are multiple failures that can causes the TBI trucks to have low fuel pressure other then the fuel pump. It could have a fuel pressure regulator problem.
As these trucks get older it is becoming a common problem for the rubber hose in the tank between the fuel pump and the sending unit to split. Some people notice when this starts happening the truck will run better with more fuel in the tank.
I would only use original equipment parts on the EGR valve and the fuel pump. If an aftermarket fuel pump was used I would be suspicious of it. I have seen so many fuel pumps from other manufactures fail in the warranty period or just after the warranty is up that I suggest only using an OEM pump.
The TBI fuel pressure specification for small block Chevy’s is 9 – 13 PSI with the truck running.
As for testing the pressure I'll do that as soon as I figure out how. As you know these trucks don't have a test port.
I don't remember what kind of pump i used, it came from NAPA, but I know about the problems with them. I replaced the one in my 97 Blazer with a aftermarket one, Bad idea!
Thanks again for your replies.