Weird crank but no start issue

[jhornsby3]

I am totally lost with this one.

Went into town to get some errands done. Pickup starts fine and runs great everywhere we stop. Our last stop, I shut er down, and go in for a couple minutes, come out and it cranks, tries to light but never does. Normally the dash will go through it's check and the "check engine" and "security" lights come on. When it's acting up, nothing. Only the glow plug light for a micro-second, flash. I tried to pump the hand pump and it gets hard but won't hold pressure. CTS3 reads 4.930 at normal idle and 2.0XX at cold start. When this was going on it was reading anywhere from 1.000 to 1.200. After hand pumping and walking back around to the drivers seat, no change in the pressure. Temp on the fuel return was at 118*f and after 45 minutes was at 122*f. No codes came up, at all.

Sat in the parking lot for 45 minutes and got it to light after pumping the hand pump and holding my foot to the floor. I noticed the gash lights "check engine" came on. After it lit up and was running, the "security" light stayed on. Drove home the 25 miles and ran great. Fuel pressure was at 1.430 idle and good cruising. Sitting in driveway, fuel temp was at 118*f. Shut it down, waited about 5 minutes for heat soak and it fired right up, like nothing ever was amiss.

This is the third time this has happened. Yesterday, I got suckered into pulling my truck and trailer with our tractor on the back, for the FFA in a parade. Never an issue, the whole time.

Anybody ever hear of this type of problem, and can offer any kind of help?

 

[jrsavoie]

What are you working on?

What's your fuel pressure while all this is going on?

 

[jhornsby3]

What are you working on?

What's your fuel pressure while all this is going on?

My 2004 K3500 with the LB7. And all of the pressures are listed above.

 

[jrsavoie]

My 2004 K3500 with the LB7. And all of the pressures are listed above.

Do you have a lift pump?

 

[MrMarty51]

Welcome to the forum J.

 

[WarWagon]

Normally the dash will go through it's check and the "check engine" and "security" lights come on. When it's acting up, nothing.

Focus on this. No dash lights = NO ECM Power! Offhand I suggest it's the ignition switch.

 

[jhornsby3]

Do you have a lift pump?

Yes, it has a lift pump.

@WarWagon is thinking close to what I was thinking. Since this is so sporadic, and doesn't happen on a regular basis, it has to be something electrical. For the $20, I might just rebuild that hand pump as a maintenance item. The shop that originally did the injector work screwed things up so bad, the dealer had to replace most of the "soft" items in the fuel system. The first shop also said the CP3 was toast and tried to get me to replace that. I had the dealer check the serial number against the pick up and they said it was the original to the truck and that the shop did not replace it. But this wasn't an issue until of late.

 

[jrsavoie]

Yes, it has a lift pump.

@WarWagon is thinking close to what I was thinking. Since this is so sporadic, and doesn't happen on a regular basis, it has to be something electrical. For the $20, I might just rebuild that hand pump as a maintenance item. The shop that originally did the injector work screwed things up so bad, the dealer had to replace most of the "soft" items in the fuel system. The first shop also said the CP3 was toast and tried to get me to replace that. I had the dealer check the serial number against the pick up and they said it was the original to the truck and that the shop did not replace it. But this wasn't an issue until of late.

I'm curious why the hand pump.is necessary, if you have a lift pump.

Won't the lift pump pressurize the hand pump to expose a leak?

If your losing pressure at the hand pump, it sounds like you have a fuel issue as well as an electrical issue

 

[WarWagon]

is thinking close to what I was thinking. Since this is so sporadic, and doesn't happen on a regular basis, it has to be something electrical.

Check for codes. A nightmare long list is also the same problems outlined below as the ECM "fries" on low voltage, brownout, and can't function properly until voltage is high enough.

So clean grounds. Separate and load test batteries. NPF? than replace the ignition switch and autopsy the old one to see if it has burnt contacts. (Thus knowing if your repair did something.) Only the airbag recall dwarfed the killer ignition switch mess GM had and that wasn't even the burnt contact problem. These years are not known to be reliable so it's one of the few parts I suggest throwing at something.

If the hand primer is soft and you have a lift pump assumed to be pressurizing the hand primer: again it ain't got power to run so back to electrical.

 

[jrsavoie]

I install a toggle switch to run the lift pumps on everything I install them on.
Just fused power to the toggle switch and then to the exciter on the lift pump relay.

 

[jhornsby3]

Sorry guys. It's been a crazy couple of weeks. Goats breaching fences, rocket launches and more goat crap.

Batteries are new and I swap them for position at every oil change. Owning a 6.5l taught me that one. I have gone through all of the grounds and all but one was clean. There has been zero codes and that is driving me batcrap crazy.

It hasnt done it again since the last time. And when I say the hand prime gets soft between cycling the key to start, it's only taking 3 to 4 short strokes to get the thing hard. When the truck is running, it's about the same as when I cycle the key and not starting.

As for putting a toggle switch, been there, done that. I'm not the only one that drives my vehicles. Last time I did that, someone fried the glow plugs and ruined a fuel pump after the truck sat a few days with them both running. So I'm not much in the way of adding some southern engineering to my vehicles.

I have a couple of weeks before the next event that will draw me from the farm. So, I plan on getting on the ignition switch and filter head rebuild.

 

[WarWagon]

Batteries are new

SO?! Test them and be sure they aren't the problem. Never give anything a free pass because it's "NEW". Offhand: Defective, died an early death, or bad cable not charging a battery ruining it... The not clean ground if it was a battery ground could have murdered your new battery. Just saying do not chase your tail and "find" a bad battery after the parts cannon didn't fix it.

Again ECM's need a minimum voltage to make a "0" become a "1". Not enough voltage and the "0" stays a "0" causing ghost codes and other weird things not working.

And when I say the hand prime gets soft between cycling the key to start, it's only taking 3 to 4 short strokes to get the thing hard. When the truck is running, it's about the same as when I cycle the key and not starting.

Doesn't hurt to have a spare part, but, these filter heads are known to crack and suck air = hard start. IMO your electric lift pump, that should overcome a crack and bad primer, isn't keeping up with the running engine if the primer is soft with the engine running. Eliminating the "not good enough even for a 6.5" lift pump for the Duramax IMO was a good idea. Regardless why can't the lift pump keep up? Restriction somewhere, lost power, bad lift pump, restricted ... I would put a pressure gauge on it. If the pump you have can't keep up consider removing it completely (back to stock no lift pump) or go big with one that can. (Or if you have clearly you have a problem!)

End of the day your main problem isn't the fuel system: it's electrical.

 

[MrMarty51]

And when the battery tester passes the battery as an OK, then get out the hydrometer and check the state of charge for each cell.
I have seen batteries that tested just good and still have a dead, or near a dead cell.

 

[jrsavoie]

Sorry guys. It's been a crazy couple of weeks. Goats breaching fences, rocket launches and more goat crap.

Batteries are new and I swap them for position at every oil change. Owning a 6.5l taught me that one. I have gone through all of the grounds and all but one was clean. There has been zero codes and that is driving me batcrap crazy.

It hasnt done it again since the last time. And when I say the hand prime gets soft between cycling the key to start, it's only taking 3 to 4 short strokes to get the thing hard. When the truck is running, it's about the same as when I cycle the key and not starting.

As for putting a toggle switch, been there, done that. I'm not the only one that drives my vehicles. Last time I did that, someone fried the glow plugs and ruined a fuel pump after the truck sat a few days with them both running. So I'm not much in the way of adding some southern engineering to my vehicles.

I have a couple of weeks before the next event that will draw me from the farm. So, I plan on getting on the ignition switch and filter head rebuild.

I install a safety toggle switch under the hood so I don't have to climb in and out of the cab while priming or doing diagnostics.

In your case, I would hit the toggle instead of the bulb.

I've never used it for driving.

 

[ket019]

Based on what you've described, it could be a fuel delivery problem, maybe related to air getting into the system or a weak fuel pump. The fact that pumping the hand pump helps temporarily suggests it might be related to fuel pressure or air in the lines.