gnknt

ok.. i have done a search on here to no avail. Everytime I find a post with my exact problems.. it just stops with no final answer. So I decided to post this question to get my answer.

facts: wife was coming home from work tuesday and as she got on freeway, truck ( vortec v6) just lost all power, no bucking or stumbling just cut off. She tried to restart but all it would do was crank. if I let it sit over night it will fire right up and run for 2 seconds then die out.

I tried starting fluid, would start for 2 -3 seconds and slowly die out again.

recent history: replaced fuel pump about 6 months ago, fuel filter 2 months ago, cfi unit 2 months ago ( during snow storm lol) spark plugs yesterday, cap and rotor 2 months ago.

Fuel pressure (KOEO) 60 psi after about 3-5 minutes it drops to 50 psi and steadly drops at that same pace till pressure is 0. pulled line in front of fuel filter and turned key on, good strong steady stream from pump and filter. No signs of gas leaking, or smells of gas. Holding pedal down ( flooded condition) does nothing. Once started pumping footfeet does nothing.

I have heard lots of possibles; pcm, ecm, tps, cps, other cps. I also hooked up my spark tester to the sparkplug wire and plug (inline kind) nice bright orange glow.

any ideas? I am at my wits end... I told wife if I could I'd blow the damn thing up... vortec v6 is the biggest piece of crap I have ever worked on. Sorry if I offened the vortec elite, just MHO.

thanks for your help,
Bigdaddygb

ctwright

Problem isn't in crank sensor you are right if you are getting spark and also the fact that it will run for a bit by using starter fluid, I know you recently replaced your fuel pump, but open your gas cap and listen while you get your wife to turn the key on, you should hear it come on for a few seconds, if you do not it doesn't necessarily mean that the pump is bad it could be a problem in the wiring somewhere getting power to it, but do that and get back to us and we will go from there.

ctwright

Oops my bad, I need to start reading the whole threads before I start posting. You need to check that you are getting power to your injectors, the fact that you are able to start it after it sits over night is probably where some of the gas seeps through over night and leaves enough to ignite, no problem with your pump, sry for not paying attention.

You should have 12 volts to one of the wires going to each injector with the key in on position. The other wire should get a ground pulses from the pcm. You could have a blown fuse somewhere in the fuse panel or it could be a bad sensor not sending the signal to the pcm so it can send the ground pulses to your injectors. I think the cam sensor is the one used for fuel injection.

I am leaning more towards a fuse being blown. Check with a test light and put the clip on a ground somewhere and probe the wires at each injector with the key in on position, one of them on each injector should make it light up.

gnknt

ok. i have one injector it's under the manifold. I has that sucky CPI unit with one injector and 6 spider injector tubes. i recently replaced it about 2 months ago. I will check fuses in a few it raining now and wil stop later today.

Also from your first post, I hear the fuel pump everytime i turn on the key. I feel as thoug it may be a CPI problem because if I turn key on and off a few times ( primeing several times in a row..) it almost wants to start up..

gnknt

checked fuses, they are fine, even swapped the two fuses that are in glove box location. no change. my next step is a scanner. But it will have to wait till payday.

ctwright

Do you have a test light or multimeter, if so did you test to see that one of the wires going to your injector has 12 votls + with the key in the on position, sometimes a problem could be after the fuse like maybe a loose connection behind the fuse box or something?

old_master

Adding starting fluid makes it run, and fuel pressure dropping to zero: those are both classic symptoms of a fuel delivery problem. How long after the pump shuts off before pressure drops to zero? If fuel pressure drops to zero, there is a leak somewhere. If you don't smell fuel or see a leak, most likely the check valve in the fuel pump is not operating properly, or the flex line at the pump is leaking in the tank. What brand fuel pump did you install?

ctwright

By my calculations going from what he just gave there it would be anywhere from 18 minutes to 30 minutes.

ctwright

I agree with Old Master on needing to get the pump checked. However that shouldn't be causing you not to get it started. If you have plenty of pressure when you first turn it on and it does hold for a little bit, you should be able to get it started. Like I said you need to make sure you are getting power to your injector. And if so you need to make sure that the injector is spraying.

ctwright

I already replied to this, but I'm replying again. Reading this thread I never seen any mention of a check engine or service engine soon light on which probably means you do not have a code stored in the ecm for anything. A scan tool is not your next step, I would get a noid light and hook up to your injector, well, I would actually use a test light or multimeter like I said and speaking of that you never even came back and said whether or not you have done that. A scan tool will not tell you everything that is wrong with a vehicle you. You would pay less money to get a haynes manual and look up how to pull codes yourself for your vehicle without a scanner, and also have a lot more helpful troubleshooting advice to offer as well. Either way you don't need to check the computer for the problem you are having.

old_master

For checking injectors, use a noid light or digital multimeter, a test light will damage the injector driver in ECM.

ctwright

I should have better clarified what I was saying, I was just talking about checking the side of the wire that is supposed to have 12 volts on it with the key in the on position with the alligator clip to a ground somewhere within the engine compartment, if you have a diagram that shows which one and know which color wire it is you will not damage anything checking that one with the test light. However if you are checking for your injector pulses from the ECM which is the other wire he is probably right you should use a digital multimeter for that, you would take one lead from the meter and put on a battery positive somewhere and the other to that wire. I'm assuming that what happens there if you use a light instead of the meter to check for the ECM pulse is the injector and the light together may draw too much current than the circuit in the ECM can handle or something maybe Old Master can get back on that.

old_master

Exactly correct! When checking for ground with a test light, the alligator clip is connected to battery positive. When the ECM sends a ground pulse to the injector, B+ voltage will be sent directly to the injector driver through the test light filament and destroy the injector driver.

gnknt

ok. I have a haynes manual and it's not much help for my problem. I have checked the coil, and have a multimeter I use for testing. I also use a test light, and an inline spark plug tester. In order for me to check the fuel injector I will have to pull off the whole intake as the injector is under the intake. As for the leak down of fuel pressure, yeah about 30 minutes is right for the leak down to zero. But from whay I know you only need enough pressure for the start and then pressure will drop off anyways once started.

Also for check engine light, wife said all lights came on when it died out and she told me last night that the check engine light had been coming on and off for the last 2 weeks. Gotta love women..... grrrr.. anyways... i checked the fuse box in glove box and have a single red wire not connected to anything in there... it goes across towards dash but not sure what too.. I plan to see if it has voltage and see if I can see behind the fuse panel to see if it broke of somewhere. It would be a clean break though as it is right down to the top of the plastic casing on the wire.

ctwright

I'd have to see a picture to see what you are talking about, I've never seen one that you can't get to like that(where you would have to pull an intake). Nothing else the connector part has to be somewhere where you can get to to check for voltages at least.