5.7 vortec long crank

[slow_c1500]

Does the check valve seem like the next likely issue?

 

[1990Z71Swede]

Nope, Its Something else, I think. How long is this long crank now? And what is the CTS reading when it does this?

 

[slow_c1500]

Crank is now about 4-5 sec. What do you mean by CTS reading? And are you referring to the one in the drivers side cylinder head, or the one on top of the intake manifold?

 

[Schurkey]

The one telling the computer how much fuel to add.

Connect scan tool, look at coolant temp.

 

[slow_c1500]

So I connected a scanner after the truck had been sitting for a couple hours (when it has hard start problems):

KOEO: 167 F
While cranking: N/A
After starting: 167 F
After a short drive: 199 F

Tomorrow after it’s been sitting overnight (when it’s not a long crank) I can get readings to compare it to.

 

[1990Z71Swede]

The fact that there is no CTS reading while cranking might be a/the problem. It might also be totally normal, depending on how the scan tool/OBD Port is powered. Does all other inputs also disappear from the scantool while cranking? The MAF, TPS and RPM and possibly a couple others should have a value. If just the CTS and maybe one or two of the others disappear, there might be a grounding issue. If RPM disapear it is most likely just the scantool that does not receive data when cranking. If there really were no RPM signal to the ECM the car would never start.

 

[slow_c1500]

The fact that there is no CTS reading while cranking might be a/the problem. It might also be totally normal, depending on how the scan tool/OBD Port is powered. Does all other inputs also disappear from the scantool while cranking? The MAF, TPS and RPM and possibly a couple others should have a value. If just the CTS and maybe one or two of the others disappear, there might be a grounding issue. If RPM disapear it is most likely just the scantool that does not receive data when cranking. If there really were no RPM signal to the ECM the car would never start.

Ok I’ll test that out too.

 

[slow_c1500]

I don’t think the coolant temp sensor reading N/A during crank is a problem, since the RPM does that too.

 

[1990Z71Swede]

Does it still start right up when sitting for just 10-15 minutes? If it does I would say it is still to rich upon startup. I'm reluctant to say you still have a leak somewhere, but start with retesting fuel pressure now that you have been driving it around for a while to see if things have changed for the worse. (Not sure if you can test that on a vortec without taking the manifold apart again) You could also try starting it with zero fuel pressure or disabled injectors to see if it starts, just breefly obviously. If it does, fuel is leaking into the cylinders somehow still

I have a similar issue on my suburban, (possible leaking injector) and I feel giving it a little trottle when cranking helps. But that's a gen IV engine so it's different in many ways.
Maybe try that anyways to see how it reacts?

 

[slow_c1500]

It does still start right up after ~10 min. I will try the disabled injector test. Would I just unplug the injector connector and fuel pump relay, and relieve the fuel pressure?