all the wires go to fuses and control circuits. the prob could be ,,ANYWHERE IN ANY WIRE.
if you pull the pump and find it good, then you will back up and test everything else!!. thats backwards!!
electronic servicers,radio/tv use a 4 step approach.
isolate to the :
1 section,the big picture
2 stage,within the section
3 circuit,within the stage
4 the PART,comes last,part within the circuit


ex,when u check a fuse, good, how do you know the wires on each side of the fuse are connected to it? if u dont know u r pitw!

the parts checkers have a big job,checking all the good parts,till they stumble into the bad ONE!
think about how to apply those 4 to the hummer

 

Going back to mechanics class at the local tech. college ages ago....lol! there are truly only three basic components to run a naturally aspirated engine.

F
A
I

Fuel
Air
Ignition

You say you are getting ignition.
You have not said if your getting air????
Fuel is in question?

1st thing is to make absolutely certain any moduals such as:
Crank
Cam
MAF
are functioning correctly.
Clean the TB really good.
Swap the injectors with known (NEW) good ones.
Swap spark plugs with (NEW) good ones.
Verify all fuses are good with (DVM) and make certain you have voltage/current at each leg if applicable.
Did ya swap in a (NEW) air filter?

These are all the things I do before I'll even dream of dropping a gas tank.
Also, Techron is a great add in gas tank detergent.

I believe the screen on the pump can be come clogged.

Chris

 

And NO you don't have to buy new injectors, just it is a hel* of a lot easier than dropping a tank. You could swap them around when changing the spark plugs.

Chris

 

Or even better you could just take it to someone and have the problem diagnosed properly instead of wasting money for guesswork. Makes it a lot easier to fix when you actually know what is wrong.

 

I know the spark plugs (ignition) are good due to the vehicle running when I spray carb cleaner in the intake hose (stated in my 3rd or 4th post). This also means that I am getting "air" or else the carb cleaner would not be getting into the cylinders. So it is narrowed down to fuel. I don't think that swapping injectors around is going to prove anything (because I could be swapping around bad injectors or good injectors - the results being the same - car won't run).

I think the next and easiest step is to check the fuel pressure. I have a gauge. I just don't think I have the right adapter. It looks kinda like an oversize tire/wheel valve stem threads, with a central valve that releases pressure when you press in on it. I will go to the local parts store to pick that up if they have it. If pressure is bad, I'm just ordering a fuel pump off of ebay. ~$322 + free shipping (OEM AC Delco). Pricey, but cheaper than the same part number at a dealer $656, and not available anywhere within an hour of me till Monday (I called a couple dealers today, all the same price).

The only other thing, I can think of would be that the pump is not getting voltage to to a wire short somewhere. That would suck. But I am not sure I can even reach up there to get a multi-meter on it without dropping the tank.

One other random thought is the dreaded "Passlock" issues I referenced in one of my above posts. I will post a separate pick of the dashboard.

 

Can someone go out to there H3 and do this quick test for me?

I get in, turn key forward but don't attempt to start car, just turned forward enough that you could work your ventilation fans and such. After everything lights up for a few seconds, most of them should shut out.

Is the light with the padlock symbol on it supposed to be lit up or not (see picture attached)? After I turn the car over and release the ignition key, it goes out (obviously the car is still not starting, so you probably couldn't simulate this one).

But could someone tell me if that is a norma light? I never seen it before, but then again maybe I just wasn't looking.

Note: my doors were closed. Don't think it should matter, but just thought I would state the obvious.

 

Who should I take it to? Do you live nearby, maybe you could come take a look? The closests dealer is at least 30 miles away. I don't own a tow truck, nor am I willing to pay somebody $150-$300 to take my truck to a dealer, that is then going to charge me $650 for a fuel pump + $(who knows how much to install). If I replace the fuel pump and it is not the issue, I have wasted $322 dollars. Much less than the $1000 or more it might cost me to haul to a dealer and have them do the work.

So far I haven't wasted any money, besides the initial 5 mile tow to get my wife and screaming baby out of the hot sun and the local mechanic's initial diagnosis.

And I should note, that I do in fact want to "have the problem diagnosed properly". Hence me posting all the details on a site, which is specific to my vehicle, to get some answers. Even the mechanic told me NOT to just change the fuel pump He recommended researching it, due to not being familiar with the other possible causes on this specific vehicle.

Maybe if I was talusfan, I would pay the local mechanic to do the research, at $40 per hour. (5 hours logged so far with my internet research)

Thanks for everybody else's help so far.

 

the fuel pump runs on electricity.

it must have 2 wires going to it from ,,somewhere.

if you find somewhere,like a fuse and ground,,,

you can check continuity from those points, instead of going to the tank.

think of it as a light bulb at the end of two wires.
it will show low resistance across those wires.

if it shows open,now you may have a pump problem.

you really should be looking at a wiring diagram,instead of making guesses or taking wild advice.

an open circuit ,,thats a problem,all the other stuff is guesses,,,
by by

oh u did change the pump relay and fuse first huh
continuity would need to be from relay to pump.

darn could be relay,,,

 

Security light. This light will come on briefly when you turn the key to START.
The light will stay on until the engine starts. If the ignition is turned on, and the light flashes, the Passlock system has entered a tamper mode. If the vehicle fails to start, see Passlock stuff in your manual.

If the ignition is turned on, but the engine is not running, the light should be on solid.

 

You know back in 1989 I had a IROC-Z28 5.7 that did the exact same thing you described mine would run when you squirted gas in the air intake, it would stall etc. It ended up being a short in the PCM.