Serious Hard Starting Issues Continue...HELP!

[Doubeleive]

well good luck then, 45 is still low, and any fuel pump can go bad or be bad out of the box
not saying that's what it is, but to say they never are bad out of the box is presumptuous
at any rate a fuel pressure test is a go-to thing for no start, if the pcm is dumping fuel in there is reason why
check the coolant temp sensor, map sensor, 02 sensors, check injectors.

 

[Fless]

I’ve never seen somebody who needs help come on here and act like this much of an a$$hole. I sure won’t be trying to help after the attitude I’ve seen you throw at some of the most helpful members you’ll find anywhere. And don’t start several threads on a single issue, that’s completely uncalled for and disrespectful to others as well as a waste of time for everybody who might actually still want to help you. Which isn’t me.

I agree; asking for help and then outright discounting suggestions is disrespectful and counterproductive. We know you're not happy with it, so you may want to consider cutting your losses. Or seek the help of a competent shop.

The last suggestion I'll make is that the ECM could think the alcohol content is high and it's adding fuel to compensate. You need a scanner that can look at that and not just assume that the value is correct. Verify. Look at your fuel trims and do an injector leakdown test. If your fuel pressure gauge is accurate, the KOEO pressure is out of spec for some reason, whether that's the fuel module, FPR, or leaky injectors. And the KOER pressure shouldn't be more than around 43-45 psi. 50-some could be too high; it's way above normal for these trucks.

I've said enough now, going 10-7.

 

[TylerHagerdorn]

I’ve never seen somebody who needs help come on here and act like this much of an a$$hole. I sure won’t be trying to help after the attitude I’ve seen you throw at some of the most helpful members you’ll find anywhere. And don’t start several threads on a single issue, that’s completely uncalled for and disrespectful to others as well as a waste of time for everybody who might actually still want to help you. Which isn’t me.

Oh so you're name calling now? Yeah that's real mature. Sorry that I'm getting sick and tired of repeating the same shit over and over again and getting the run around and not much actual help. If I have to repeat myself I get very angry. I didn't use vulgar language or anything or call anyone names. I can make as many posts as I want. Sorry that bothers you but nobody was replying to my other posts so I made a new one with updated information. This is supposed to be a place for knowledgeable people to help others with a problem they can't get figured out. Sorry I'm so sick and tired of dropping money on this pile of crap. My Yukon xl I owned had not one single issue and this truck has given me nothing but problems since I got it. Again I didn't call anyone names or get vulgar with others. If I'm frustrated, it's going to come out in a frustrated tone. Just how it goes. If you take it so personal then you need to just move on. Because saying what you just said makes me even more mad, because you're not helping the situation. You're name calling which is horribly immature. All I'm trying to figure out is how to test and see which injectors are faulty now. The pump isn't bad. The regulator isn't bad, the filter isn't bad. But instead of helping me with injector issues, everyone wants to say it's the pump or the regulator and not help me. So yes, I'm going to get frustrated. Most people that have commented know that I've had this issue for awhile. So instead of making me repeat myself, it's very easy to find my other ones and read them. I searched this forum up and down and read everything I could possibly related to my problem. Have a great evening there. Your rude words aren't going to hurt me.

 

[TylerHagerdorn]

well good luck then, 45 is still low, and any fuel pump can go bad or be bad out of the box
not saying that's what it is, but to say they never are bad out of the box is presumptuous
at any rate a fuel pressure test is a go-to thing for no start, if the pcm is dumping fuel in there is reason why
check the coolant temp sensor, map sensor, 02 sensors, check injectors.

Look Wes, I didn't mean to come off so harsh or mad at you. That wasn't my intentions. So I'm sorry. You've commented on my posts before so I figured you knew some of the issue going on.

The coolant temp sensor is new, as well as the connector because the old one was hanging by a thread in the sensor. The map sensor is fine, O2 sensors are fine. I read in another forum that negative LTFT is a sign of a leaking injector. My LTFTs have been negative since I've been chasing this issue. More negative than normal. Never goes into the positive or 0. I have a decent scanner, but the one we have at work is one step up. It has a fuel injector test mode that tests injector pulses as well. I hooked it up and wrote down all the values for each injector. Here's the results.

When it kicks on the injector it goes up to 50psi then sits at 45 when it clicks off on all 8.
Then when you start the injector pulse drop test, each injector went down to 35psi, except for cylinder 3 and 4. They went down to 30 psi from 45. I'm no injector expert, but thats not a good sign is it? That's leading me to the conclusion that 3 and 4 are faulty.

When running even from cold start the pressure was 51. Which is in the 48-54psi spec on the flex engines. Soon as you kill the truck, it drops to 40. Within an hour it drops to 20, then after two hours it's down to 0.

Cycle the key on and off and back on and it will fire up without hesitation. Before on the old pump, it wouldn't do that. It wouldnt start on any amount of primes.

So, what's the easiest way to check for leaking injectors? Pull the rails and hold them over the openings they sit in and hit the key or pull the pump relay and jump it? The only thing left to check is the injectors. Even if it's dropping fuel into the cylinders it can evaporate off from the engine heat. I was not seeing wet plugs or smell of fuel on the plugs. But that also wasn't right after it had been running. I have no problem pulling the rails.

 

[TylerHagerdorn]

I agree; asking for help and then outright discounting suggestions is disrespectful and counterproductive. We know you're not happy with it, so you may want to consider cutting your losses. Or seek the help of a competent shop.

The last suggestion I'll make is that the ECM could think the alcohol content is high and it's adding fuel to compensate. You need a scanner that can look at that and not just assume that the value is correct. Verify. Look at your fuel trims and do an injector leakdown test. If your fuel pressure gauge is accurate, the KOEO pressure is out of spec for some reason, whether that's the fuel module, FPR, or leaky injectors. And the KOER pressure shouldn't be more than around 43-45 psi. 50-some could be too high; it's way above normal for these trucks.

I've said enough now, going 10-7.

It's supposed to be 48-54psi on the flex trucks, even when running. It's supposed to drop when you hit the accelerator then come back up when you're at a steady rpm. Long term fuel trims have been negative for a long time. Never gone to 0 or positive. From what I read on another forum, that's a sign of a faulty or leaking injector.

So my last question is...do I just pull the rail up out of the injector holes and hit the key or jump the relay and watch them? I suspect two injectors are faulty as I did a fuel injector test/injector pulse drop test on our scanner at work and cylinder 3 and 4 went much lower than the other 6. Injectors are the only thing left. I've replaced both purge valves, regulator, pump, filter, MAF sensor, coolant temp sensor. Map sensor is good. Grounds are good. No fuel leaks externally. Plugs were dry and didn't smell of gas but that was after sitting for 2 hours. If I cycle the key twice it'll fire right up without hesitation. With the old pump, it wouldn't fire on any amount of key cycles.

 

[Doubeleive]

probably have to pull the rail.
any other ideas @iamdub @randeez

 

[Scottydoggs]

got a cel for a bad content sensor and not willing to fix a known bad item. like it dont have a thing to do with the long cranking or no start. rule one of auto repair, fix all known issues first...... so good luck buddy.

problem sits between the steering wheel and seat im sure of it now.

 

[BG1988]

Fuel pressure when running is 50-51 which is now within spec. Old pump was only at 45 max when running. I got to work at 2, I shut the truck off with it connected and after I shut it off it went to 40psi. After an hour of sitting it was down to 20psi. It's now been two hours and the pressure is down to 0psi. I've checked the plugs and they've been dry no gas smell or anything. Not right after running the truck but an hour or two after. Only thing I can think of now is maybe a leaking injector? My buddy said with the heat in the engine the fuel could evaporate fast

most likely you're cranking too fast pre 2007 you had to wait for a second or two before cranking try doing that (at lest i had to do this on my impala 2003 I have see others had long crank time like i did also)

try key on for 3 seconds then start the engine see if that fixes the issue
it had 187k miles before it went bust (transmission) but still had the original fuel pump

 

[BG1988]

well good luck then, 45 is still low, and any fuel pump can go bad or be bad out of the box
not saying that's what it is, but to say they never are bad out of the box is presumptuous
at any rate a fuel pressure test is a go-to thing for no start, if the pcm is dumping fuel in there is reason why
check the coolant temp sensor, map sensor, 02 sensors, check injectors.

mine works fine with 44-45PSI 6.0L (note: positive fuel trims 7-10) but on a cold start it's 59psi (410kpa) then instantly drops to 45psi (310kpa) after 10 seconds.. so 45psi is correct running psi

 

[BG1988]

I agree; asking for help and then outright discounting suggestions is disrespectful and counterproductive. We know you're not happy with it, so you may want to consider cutting your losses. Or seek the help of a competent shop.

The last suggestion I'll make is that the ECM could think the alcohol content is high and it's adding fuel to compensate. You need a scanner that can look at that and not just assume that the value is correct. Verify. Look at your fuel trims and do an injector leakdown test. If your fuel pressure gauge is accurate, the KOEO pressure is out of spec for some reason, whether that's the fuel module, FPR, or leaky injectors. And the KOER pressure shouldn't be more than around 43-45 psi. 50-some could be too high; it's way above normal for these trucks.

I've said enough now, going 10-7.

if it's a leaky injector Lucas fuel injector cleaner will do the job just pick up a few gallons and dump it in the tank

walmart has it for 29$