GMCTIM

Hi. Fairly new to this site, so if this is the wrong section, please move.
I have a 92 Z/28 5.7 TPI. Stored winters, approx 70,000 mi.
Over winter, i changed the thermostat & put a new fan temp switch / sensor in the R head. I removed the knock sensor in the block (thinking it was the fan switch for some reason) & put it back in.
I drove the car to a local show, then was going to a show approx 20 miles away & the car doesn't seem to run right. It has a hesitation / miss. Seems like it's missing on 1 cylinder. If you step on it for normal acceleration, it "stumbles" ?(for lack of a better word) It just doesn't gain RPM like it should. If you stomp on it, it revs pretty smoothly, but doesn't rev as fast as it used to.
Could my fuel pump be going out & is there a way to test it? Could it be the fuel pump relay? Is there a way to test the pump, or does it just go out one day? The fuel filter is pretty new, nothing else changed.
Could i have screwed up the knock sensor somehow?
Also, does the car need to be on a hoist for fuel pump change, or can it be done on stands (if it needs to be). Is there a way to test relays?
THANKS for any info.

GMCTIM

Anyone know how to test an electric fuel pump?

vetteoz

iTrader: (13)

Have you tested your injectors ; they don't last forever and a bad one could drop a cylinder out
Assumes your electrics are up to scratch and you have no spark problems; a common cause of bad running/ missing / stumbles

Pump problems with injection mean if pump drops out or fails ; the engine dies ; no fuel - no run
And it is not the relay because there is a seperate switch that puts power to the pump so long as the engine has oil pressure

vetteoz

iTrader: (13)

Putting 12V to terminal G of the ALDL connector will make the pump run fulltime so you can do the testing
You test to see if it will achieve a certain pressure and that it will flow a certain amount over a period of time.

Most certainly
Problem is many old pumps break down with heat so a cold test may not indicate what the pump is doing
when it has run for a while and heated up
Only real way is to test drive with a pressure gauge taped to the windscreen ( outside )
so you can see what the fuel pressure is doing when the engine plays up

GMCTIM

vetteoz: Thanks for the info about the ALDL connector.
Do you know how much pressure the pump is supposed to produce?