So a couple months ago i was driving from Washington to Alaska and when i stopped for fuel it was hard to start, took like 7 ot 8 seconds of cranking to fire. It ran fine once it started so i thought i got some bad fuel. When i stopped next for fuel it would turn over fine but it wouldnt fire. My buddy towed me home and i left for work the next day and just got back a couple days ago. I just returned home, drained my fuel, replaced my fuel filter, primed and bled the system and added some fuel additive. Wouldnt start. The guy at the dealership thought it might be injectors but couldnt tell for sure and told me to spray a little silicone spray in the intake tube as a starting aid, it started but it still wont start on its own.

Question- How can i tell for sure if it is the injectors, I dont have any white smoke, and no noticeable fuel in the oil but have some loss of power.

Thanks

I would check for a leak in the fuel system and the CP3 first. If you can check the balance rates after you get it started, that might give you an indication on them.

I would think the same, I have not heard of injectors causing a truck not to start. (at least that I can remeber)
Did you try to reprime the system when it wouldn't start?

how do i check the balance rates?

Yes I reprimed and rebled it several times

how do i check the balance rates?



EFI or a Tech2. Im sure scanners like Modus and Solus are able too.

Ok so i got a buddy who is going to hook it up to a computer and check them, what should range should they be in, and how can i diagnos the problem with the rates given?

Thanks alot for all your guys help!

the GM spec is +/- 4 in park and +/- 6 in drive at operating temperature. Some feel that's a little loose.

My injector flow rates from a Snap on scan tool, truck at operating temp

Park- 1-.34 to .21, 3-.38 to .24, 5-.35 to .11, 7-.41 to .26
2-.49 to .34, 4-.31 to .00, 6-.41 to .27, 8 .49 to .34

Drive- 1-.55 to .22, 3-.56 to .24, 5-.55 to .11, 7-.56 to .26
2-.60 to .34, 4-.47 to .00, 6-.56 to .27, 8-.61 to .34

Im gonna replace my fuel pressure regulator on my injector pump and see if that does anything

Did you check the desired vs. actual fuel pressure? If the CP3 is bad, replacing just the FPR won't work. I had a pretty bad FPR but didn't have a no start condition. I'd check the CP3 before you tear into it.

Your injectors are returning to much fuel while cranking and your cp3 can't supply enough fuel to let it start normally, you need to check your fuel pressure have your buddy hook up his scanner again, go to functional tests, to fuel pressure test, scroll data till you see desire fuel pressure and actual fuel pressure,now you can perform the test command fuel pressure to 160 Mpa look at you actual fuel pressure if you get 160 Mpa your injectors and cp3 are good if not GM says diagnose high pressure fuel system If your injectors are returning to much fuel you wont see 160 Mpa I just did one at work with the same conditions you have and its fine now

Checked with Snap-on scann tool

At idle-
ACT FRP-33 to 36 DES FRP-34

Couldnt get above 98Mpa because i was redlined
At DES FRP 98Mpa ACT FRP 97 to 98Mpa

Checked with Tech2 scanner dont know how to switch from psi

At Idle ACT FRP-4966 DES FRP-4930
At 2000rpm ACT FRP- around 9770 DES FRP- around 9800

do this test at idle, if you have found the right functionality test on the scanner get into the test mode and command the Mpa up to 160 while watching the actual, I've done a number of these injector jobs and I could never command the Mpa any higher than approx. 120 to 130 Mpa

Can this be done with a snap on scanner tool

Yes I use the snap on Solis scanner

So i took it to the dealership today and they told me it was the injectors so looks it looks like i have a weekend project, if anyone has any tips tricks or suggestions that would be awsome.

Thanks for all the help guys!

did you ask the dealer if they were able to command Mpa to 160, how did they determine it was the injectors

they measured the return fuel and they couldnt command more than 76Mpa.

I know there is no definite answer to this, but if the balance rates are good, what is expected life/how fast can they go bad, like is it an overnight thing or?

Does anyone know how much it costs to get balance rates and fuel system checked at the stealer?

For a complete fuel system diagnosis it cost me $120

thanks everyone for the feedback, i was able to change my injectors my self in one day. I am able to leave tomorrow and Drive from Alaska to Washington worry free. Special thanks to chuntag95 and jtw.