1995 GMC Sonoma

Engine Mechanical problem
1995 GMC Sonoma 6 cyl Four Wheel Drive Manual

I hooked up noid lights to my 4.3 TBI injector connectors and I'm not getting anything on either one of them. I know the noid light is working because I checked it against another TBI engine. I don't understand what this means.

I'm sure that it's I'm not getting power to the injectors but I can't figure out why. I have a fuse [ECM IGN 20amp] that keeps blowing but even when the fuse isn't blown and the key is turned I'm still not getting any light.

I don't know if it makes a difference but I just replaced my fuel pump and I'm sure that it's working (i can hear it) but I can't figure out where to hook up my fuel pressure gauge to check pressure. I've heard between the inlet line and the throttle body but that would mean splicing into the metal line. As far as I can tell there are no flexible fuel hoses anywhere within the engine compartment or aft of the fuel filter.

April 25, 2009.

No start condition
fuel pump was replaced
not sure if you have fuel pressure and if fuel pump working or not
no injector pulse when engine cranking
fuse keep on blowing not sure what it dose control
hope I got all
know this where we need to start is by making sure if the fuel pump working when 1st key on and or when engine cranking
if can not locate the fuel test port you can just open fuel line and have a helper turn key on for a second you should have fuel leaking and if so we know fuel pump is working
will move on to the injectors
use a test light turn key on
check for power at the injector connector
if no power check fuses and wiring
check wires coming to the TBI unit if got pinched by the air cleaner housing
if you have power
disconnect TPS on the side of the TBI unit and try starting
check TPS volts, check coolant sensor
let me know

Apr 26, 2009.
Fuel pump is working, fuel is getting to throttle body.

Still no injector pulse when I hook up a noid light. I used a multimeter and a wiring diagram to check for a short, found nothing. The fuse [ECM IGN] which runs from my injectors to the vehicle control module to the fuse panel is no longer blowing when I try to crank it but it still won't start.

I'm beginning to suspect something is wrong with the VCM (which powers my injectors) but I don't know how to test it. And I'm also wondering if there could be something else wrong before I spend the money to replace it.

So I have strong spark, a new fuel pump (working) and filter and still my truck isn't turning over.

May 2, 2009.
Changed the coolant temperature sensor and TPS. Still nothing

May 2, 2009.
Use a test light With key on do you have battery power at red wire inject #1 and also should have battery power at the white wire
let me know
dark blue wire
dark green wire
both go back to the PCM
they get grounder by the PCM causing it to pulse

May 2, 2009.
I clipped one end of the test light on to the postive battery terminal and the other end to each indicated wire.

I accidentally started this test with the key OFF.
I got a bright light for the red and white wires. I got a dismal light for the dark blue and dark green wires.

Now WITH the key ON I got no light on all four wires.

I only mentioned the first test in case it may be indicative of something.

May 2, 2009.
Clip the tester on battery negative
turn key on check if light come on
let me know

May 2, 2009.
With the test light clipped on the negative terminal, key in the on position

Yellow wire= Light comes on

White wire = Light comes on

Dark Green wire= no light

Dark Blue wire= no light

I don't know if it makes a difference but I have a VCM mounted on top of the right wheel well instead of the PCM under the glovebox.

May 2, 2009.
Test light clipped at battery positive
injector plug disconnected
have a helper crank engine for you
check dark green wire and dark blue wire
does the test light up or blink
if not suspect bad VCM (Vehicle Control Module)
need the help of a scanner

May 3, 2009.
The thing that I don't like about these forums is that the original person with the problem never responds AFTER they have their problem fixed. So I'm sitting here at 3 in the morning reading about TBI injectors not firing hoping to find an answer but just more dead ends.

May 27, 2009.
We try and ask all to update the fix but as you see it does not happen very often
what is your issue with the TBI system
Need a tool or a tester CHECK IT @
need manual CHECK IT @

May 27, 2009.