5.7 Vortec intermittent long crank --> crank no start, backfires, clunking

[99xcss4]

if you need a new cap and rotor order these they are the best brass terminals and a vent every one here with a vortec loves them and if they do not have it yet is is on their list the next time they need a cap and rotor https://www.rockauto.com/en/moreinfo.php?pk=1991918&cc=1051120&pt=7120&jsn=509

 

[slow_c1500]

if you need a new cap and rotor order these they are the best brass terminals and a vent every one here with a vortec loves them and if they do not have it yet is is on their list the next time they need a cap and rotor https://www.rockauto.com/en/moreinfo.php?pk=1991918&cc=1051120&pt=7120&jsn=509

I’ll keep that in mind. But do those pictures look normal? Or should I be worried about the colors of the contacts in the cap?

 

[99xcss4]

seen worse your rotor looks not too bad except for the circle part in the middle your imho looks worse then your rotor do either of them have carbon traces or coroded

 

[slow_c1500]

They are a little corroded, and I will replace them with the blue ones later on, but i dont think they're causing my no start problem, so they arent a huge priority right now. Its a lot more urgent that I get her running. The truck is giving 2 codes: for MAF and for throttle position. I am going to test those tomorrow with a multimeter.

 

[Schurkey]

The truck is giving 2 codes: for MAF and for throttle position. I am going to test those tomorrow with a multimeter.

Testing with a scan tool will be much more thorough, AND faster.

 

[slow_c1500]

I can see from the scan tool that those 2 sensors are still giving readings, so they aren’t the cause of my crank no start.

I also noticed smoke coming out out the intake after cranking it. It smelled a little like fuel but I’m not totally sure, could be oil. I occasionally hear a clunking sound during cranking as well. Would it be a bad idea to try starter fluid to see if it starts that way?

 

[slow_c1500]

Bump (sorry it’s kinda urgent)

 

[Schurkey]

I can see from the scan tool that those 2 sensors are still giving readings, so they aren’t the cause of my crank no start.

Are they giving ACCURATE readings?

How about ALL the other sensors?

I also noticed smoke coming out out the intake after cranking it. It smelled a little like fuel but I’m not totally sure, could be oil.

No idea how enough oil could get into the intake manifold to come out as "smoke" or mist.

I occasionally hear a clunking sound during cranking as well.

Broken tooth on the ring gear? Wiped-out thrust bearing on the crank? Sticking valve getting smacked by the piston?

Would it be a bad idea to try starter fluid to see if it starts that way?

Do you have spark? Does the distributor rotor spin when the engine is cranked? Are the plugs fouled? Do all the cylinders have reasonable compression pressure? Do all the valves move like they should when you crank the engine with the valve covers removed?

Sure...try starting fluid. See what happens.

 

[99xcss4]

can I use starter fluid to see if it starts that way?

yes you can but make shore that you have spark first and here is a psa on starting fluid imho and some others starting fluid is crack for engines I only use it if there no choise or for testing

 

[slow_c1500]

All the sensors that the scanner would display data for (with KOEO) seem to be giving good readings. Yes distributor spins when you crank it. And starter fluid doesn’t seem to help it, so that rules out a fuel delivery issue.