LLY crank no start

[Yellow Jacket]

Check the return rates? I've had them not fire when only two had a higher return than the rest.

Ok, will do... But even with it making plenty of rail pressure? 10,000 psi+ while cranking... Modded fresh lbz pump, haven't retuned regulator current yet...

How can I verify injectors are getting signal/command to fire? If I unplug one and hook meter to it, it will just throw a code and shut down 4 injectors, correct?

 

[Chevy1925]

cam sensor reading correctly? cam gear timed correctly? checked compression just for shits and giggles?

i know it aint your first time around a motor but never hurts to ask

 

[Yellow Jacket]

cam sensor reading correctly? cam gear timed correctly? checked compression just for shits and giggles?

i know it aint your first time around a motor but never hurts to ask

I've jumped a tooth on cam gear for the pulling engine... That being said, I'm not getting a correlation fault like I did in that situation... Compression is there, glowplugs are all out and I'm cranking engine over, it should be blowing Fuel out of every glowplug hole...but it's dry as a popcorn fart! I want to test if injectors are getting power and ground signal...if so, I need to send them out to be tested and most likely replaced. I find that hard to believe, but scan tool appears to be calling out a command, it's like the injectors aren't getting it, or just can't physically fire...no Fuel from any one of the 8 cylinders. VATS doesn't appear to be causing it, I could try a different crank and cam sensor, but I'm seeing both signals with no faults on the Tech 2. Just not making any sense and has me stumped!

 

[dirtydmax]

Have you ohmed the injector plugs?

 

[Chevy1925]

I've jumped a tooth on cam gear for the pulling engine... That being said, I'm not getting a correlation fault like I did in that situation... Compression is there, glowplugs are all out and I'm cranking engine over, it should be blowing Fuel out of every glowplug hole...but it's dry as a popcorn fart! I want to test if injectors are getting power and ground signal...if so, I need to send them out to be tested and most likely replaced. I find that hard to believe, but scan tool appears to be calling out a command, it's like the injectors aren't getting it, or just can't physically fire...no Fuel from any one of the 8 cylinders. VATS doesn't appear to be causing it, I could try a different crank and cam sensor, but I'm seeing both signals with no faults on the Tech 2. Just not making any sense and has me stumped!

its just strange you get smoke out the exhaust if the injectors arent firing. could you pull an injector out of the head and maybe orientate it so you can see the nozzle and hook the hard and soft lines back up, then crank over to see if fuel is coming out? have the connections been ice picked before? ohming it like dirty said isnt a bad idea either.

 

[Yellow Jacket]

Have you ohmed the injector plugs?

Ohn the injectors themselves or harness side? The ground is ecm controlled to fire them, (correct?) So I'll have to ohn to good ground, correct?

 

[Yellow Jacket]

its just strange you get smoke out the exhaust if the injectors arent firing. could you pull an injector out of the head and maybe orientate it so you can see the nozzle and hook the hard and soft lines back up, then crank over to see if fuel is coming out? have the connections been ice picked before? ohming it like dirty said isnt a bad idea either.

The smoke would only come when I was ethering it. It would hit slightly on next couple cranks while not ethering it, I think it was residual... Never did have Fuel. I ice picked all 8 connections before reinstalling the harness on this engine.

 

[Chevy1925]

The smoke would only come when I was ethering it. It would hit slightly on next couple cranks while not ethering it, I think it was residual... Never did have Fuel. I ice picked all 8 connections before reinstalling the harness on this engine.

That makes more sense then.

as for ohming it, he means from the connection at the injector back to the FICM. that whole wire. if you try to ohm to ground, you probably will see an open as the circuit isnt closed in the ECM.

did you check for any bent pins at the FICM?

 

[Bustedknuckles]

Ohn the injectors themselves or harness side? The ground is ecm controlled to fire them, (correct?) So I'll have to ohn to good ground, correct?

Use a lab scope and low amp clamp around the injector wires to see if they are being commanded to fire. Check a known good truck to see what a good pattern should look like.

Also you should loosen the high pressure lines at the injectors and make sure it is actually getting fuel to them.

 

[Yellow Jacket]

Checked a few more things tonight...

Used a halogen bulb in series and checked FICM signal, injector group power, control circuits to verify they were all good... And Ignition 1 voltage to FICM, plus I load tested the FICM grounds with the bulb and my 12V power probe...

Tested Ignition voltage to crank and cam sensors, ok

Swapped FICM's with a different one yet again, and tried a different ECM....still same results, pulled cam sensor and verified part # good and reluctor wheel was in place and tight...

Hit it with either again out of frustration, and after that it would smoke grey/black and fuel knock seemingly randomly when cranking on it's own... Seems very random and like it's confused on what timing is/should be or like it's searching for correct hit...or maybe all 8 injectors just aren't firing, it won't run but at least sounds like it's trying to find tdc or something

I ordered a new crank & cam sensor... Probably for nothing, but not sure what to try next

 

[dirtydmax]

Have a spare motor harness?it will at least eliminate that end of it.

 

[NC-smokinlmm]

You try swapping the TCM yet? They can cause a no start f the ground goes bad, maybe just try grounding the case and see what happens...

 

[Yellow Jacket]

You try swapping the TCM yet? They can cause a no start f the ground goes bad, maybe just try grounding the case and see what happens...

TCM is only thing I haven't touched or looked at... I'll try a couple things with that...

 

[Yellow Jacket]

Got it somewhat running last night... It must be the injectors, I cranked & cranked & cranked some more on it last night...it started smoking more and more and getting close to starting, I hit it with some ether and it was running rough minus a few cylinders. Hooked up Tech 2 and 3 cylinders were +15 on balance rates... Shut it off and ice picked those 3 cylinders...started it again and #5 was at -4 now but 4 & 6 were still at +15, but #2 & #8 were now at +15...

So 1,3,5 & 7 are all around -4ish.... And 2,4,6 & 7 are all +15...

I will be pulling all 8 injectors and sending them out...but I was debating on running some injector cleaner through them at idle first, to see what that does.

 

[x MadMAX DIESEL]

If your able to start and run it that upper engine cleaner gm has is good stuff. I just let the truck on about a gallon tank of fuel recycling it till it runs out


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