2000 Silverado 4.3 fuel pressure
 

Hi everybody, hoping for some guidance......

2000 silverado 1500 4.3

Crank no start after sitting overnight.
Once she finally gets started, good for the day.

Fuel pressure bleeds down after sitting several hours.

New spider
No washout under plenum
New FPR
Recent OEM pump
Compression 150 across all 6 cylinders
Got spark
Coil checked out ok.
Can't find any external fuel leaks, and no smell of gas
New fuel filter
Plugs not wet
New cap, rotars, plugs, wires

PO 300 code.... the miss seems to be worse when cold, not really noticeable once it's at operating temp

Since pressure does bleed down slowly, I figure the new pump had the check valve crap out, but she primes up to 55PSI KOEO, so I'm not understanding why it won't start after sitting.

It acts like it's just not getting enough fuel when cranking when it's in the no start situation......just sputters at the end of the crank cycle. If I keep trying, she eventually starts and runs fine, but this is after a LOT of extended crank time........

Fuel Pressure :
55 KOEO
60 cranking
50 idling
Sitting on idle, stab gas and pressure jumps to 60, then settles back to 50.

I'm not sure where to go from here.
Do these fuel pressure numbers look like they could cause no start? Maybe pump is weak by a pound or two?

I'm thinking next step dead head the fuel pump to verify the leak is in tank, but I'm still confused on no start condition after sitting for several hours......

Even if it bled to zero, it should fire up when I get 60 PSI at the rail, right?

PCM maybe not enriching the mixture?
Not sure to focus on fuel pressure or injectors......

Any guidance on what to check next?

Thanks in advance!

What's the idle rpm?

700.

No surging, idles fairly smooth

Some of the things going through my head:

Fuel pressure is what I keep thinking the most.....I've seen one place saying spec is 50 for poppets to open, and my crappy manual only states 60 KOEO- I've got 55 KOEO, but I do have 60 when cranking.......manual doesn't give cranking spec (only KOEO) so I'm honestly not sure what the FP should be when cranking,

Low fuel pressure would explain the 300 code.
But, my thought is it should be throwing a lean code as well.

Crank position or cam sensor?
That should cause more issues than just hard start.......
It would run bad all the time, right?

PCM not telling spider to inject when she's cold?
I wondered if CTS might be sending wrong info, but OBDII shows 195.....

Maybe it's time to get a noid light and figure out how to connect to the spider to see if it's giving injector pulse when cold....

Jumped time by a little?

Once it's running, it runs fine other than slight miss. No backfires, so I really don't see that being it.

Distributor?
I don't feel any play. Rotor has no play in it.

My head hurts and I think I'm over anaylizing.....

I probably should just drop another fuel pump in, but I'm just not convinced....... 60 PSI cranking should be enough to open poppets I think....... unless it's not getting signal from PCM.........

I sure wish this things injectors were up top........

my 02 ran and started with only 25 psi. i dont see yours being that low to effect the start up. whats the coolant temp when your trying to start (with this issue)? i could see it not giving enough fuel and thinking the engine is warm

I'm starting to wonder the same thing.
It's always once the block is at ambient temp.....I'm in south florida, so usually 80--90f.

I haven't thought to look at what the OBD is registering on temp when it's doing the hard start thing.......I'll be paying attention to that tomorrow morning when I go to crank it.

I drove the truck all morning today.
Shut her down, let it set a few hours, fuel pressure had already dropped to zero........but block is still warm.......
Turned key and it fires right up (I didn't even give it time to prime)......... so....I don't think it's because of the fuel pressure bleeding down.

Now, once she sits overnight and the engine is truly at ambient temp, it's a pissing match to get it cranked...........it seems to be more about the engine being completely cooled down than the fuel pressure being low.

Maybe I need to take a look at CTS again.......but last time I looked on OBD reader, it seemed accurate

cycle the key to prime the fuel rail 4 x before starting...if it starts normal...the check valve in the fuel pump has failed. replace the pump.

this has spider injection?

Yes, spider injection.
I put new spider assembly in a couple months ago, along with fuel pump and filter at same time.

Cycling the key has no affect.

I know I'm not supposed to, but even spraying starter fluid in throttle bore doesn't make it hit. I only did that once trying to figure out if it's not getting fuel.
I realize you can have a backfire and blow out plenum, but hey, got to figure it out
...... starter fluid sprayed in bore does not make it hit

I don't want to admit it, but if it helps someone else out and keeps them from doing two days of diagnostics like I did........

It was the freaking rotor...........

I put new plugs, cap, rotor, and wires less than 1k miles ago.......so no........I did not start my diagnosis there........... I did a spark check and was getting fire, so naturally leaned towards fuel........ well, I guess it was jumping spark and I just couldn't tell....

Pulled the rotor off and cleaned the heck out of it....
Saw one small carbon track............

Put new rotor on and and she fired up first try.....

Thanks for the input everybody......goes to show, always start with basics.....geez.....stupid me!