Riddle me this... hot start 'N dies, miss / cut out only in summer

[97K1500Silverado]

I’ve got this same issue going on with a new engine. You ever have any luck with a fix?

Truck hasn't had any issues lately with cooler weather. Did you get yours figured out?

 

[97K1500Silverado]

Do you have spark when restarting after 5--20 minutes?

Do you have fuel pressure when restarting after 5--20 minutes?

Does the scan tool show RPM when cranking during re-start?

Good questions, this always seems to happen when I'm far away from the garage, to check these questions when on the road with a hot heat soaked engine.... Let it cool off for 10 minutes and it starts and runs just fine, can idle in traffic hot with no issues. Randomly rears its head when trying to restart when over 90 outside and engine is hot from long drive or long idle time after long drive.

1. Spark i would have to either pull a plug or get one of those lights that go in a sparkplug wire. - If no spark then its the crankshaft position sensor or something in distributer?
2. Fuel pressure would be easy check by checking for fuel spray from the Schrader valve on fuel rail? If no fuel then its the fuel pump, fuel pump relay or regulator?
3. I have one of those cheap code readers that connects to my phone. watch the rpm live data while cranking, if none then its the crankshaft position sensor?

 

[Schurkey]

1. Spark i would have to either pull a plug or get one of those lights that go in a sparkplug wire.

Don't use a "light". Use this, or something similar, calibrated for HEI igntions. SEE and HEAR the ACTUAL SPARK.

www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=lv_ov_lig_dp_it

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- If no spark then its the crankshaft position sensor or something in distributer?

Or the coil, or the coil wire, or the ECM or the ignition switch, or the ignition fuse, or the wire harness between crank sensor and ECM.

2. Fuel pressure would be easy check by checking for fuel spray from the Schrader valve on fuel rail?

Not an accurate test. Fuel will spray even at low pressure. Many parts stores have a loaner-tool program where you buy the tool, you return the tool and get your money back. Fuel pressure gauges are common "Loaner" tools.

If no fuel then its the fuel pump, fuel pump relay or regulator?

Or ECM, or wire harness, or fuel pump fuse.

3. I have one of those cheap code readers that connects to my phone. watch the rpm live data while cranking,

Depends on the sophistication of your "code reader". Worth a try.

if none then its the crankshaft position sensor?

Or the wire harness, or the ignition module, or the ECM.

 

[Carlosm86]

Truck hasn't had any issues lately with cooler weather. Did you get yours figured out?

any update on this? Currently dealing with this.

 

[97K1500Silverado]

I haven’t had the issues since it’s been cooler temperatures. Only happens to my truck when it’s above 90° outside and truck is heat soaked from a long drive.

 

[Schurkey]

I haven’t had the issues since it’s been cooler temperatures. Only happens to my truck when it’s above 90° outside and truck is heat soaked from a long drive.

It is really unusual for a fuel-injected vehicle having the pump inside the tank, to vapor-lock.

Vapor lock is almost always seen on vehicles where the fuel pump is engine-driven; and therefore has to "suck" the fuel from the tank to the pump. The pump is heated by the engine, and lower pressure on the suction side of the pump reduces the temperature required to vaporize (boil) the fuel.

OTOH, with the pump in the tank, the pump has no engine heat to deal with, and the fuel is under pressure--9 to 90 psi depending on vehicle--which raises the boiling point just like the pressure cap on a radiator raises the boiling point of coolant.

Yeah, fuel boiling in the plumbing is "possible" but really unlikely unless it's mis-routed too close to the exhaust, or the exhaust leak is blowing directly on the fuel tubing.

Do you have spark when restarting after 5--20 minutes?

Do you have fuel pressure when restarting after 5--20 minutes?

Does the scan tool show RPM when cranking during re-start?

 

[evilunclegrimace]

pickup coil in the dist?

There is not a pickup coil in the dist on a vortec engine

 

[evilunclegrimace]

ICM, no doubt. Also check pickup coil. A ***** to replace (distributor disassembly) but prone to burnout with age.

No pick up coil in the vortec dist.