Crank no start when hot

I have had no luck searching for this. Truck seems to run fine but when I stop to shop or something it won't start. Seems to miss and struggle...let it sit a few minutes and it starts right up. When it sits its not long enough to cool down, just maybe 10 minutes.

I've pulled and cleaned coils and connections, spark plugs look good and I cleaned the throttle plate. Can you guys point me in the right direction? (no CEL, its a 4.7 auto 166k miles)

 

Check the battery, then check the fuel pump.

 

Battery is new and terminals clean. How to check the fuel pump?

 

Drop gas tank.

 

Even a new battery can have lower than expected cranking amps...

 

Load tested battery. I will only drop the gas tank as a last resort.

 

It appears related to heat, maybe the vacuum solenoids for the fuel system on the drivers side fender well. If it sits about 10 minutes it starts right up normal. Looking for troubleshooting that part of the system.
I saw another guy (Ranger47) had a similar problem but he didn't post results or answer messages.

 

Lack of fuel. I would start with the fuel filter. For Gen1, you won't have to drop the tank to replace the filter.

 

But why is it ok in 10 mins and for several miles? I have a filter and will change it but its not sensible for this type of problem.

 

The truck has 166K miles and is at least fourteen years old. Has the fuel filter ever been changed?

You've already checked the most obvious potential ignition problems and found nothing. The engine struggling to start after running fine moments before then indicates lack of sufficient fuel rather than ignition imo. There are two fuel system components that could restrict fuel flow: (1) the fuel pump (it's pumping some or it wouldn't run at all), and (2) the fuel filter.

My theory is the filter is 98 percent plugged with loose sediment inside. When the engine is started, loose sediment inside the fuel filter quickly compacts back against the filter media, but does not completely stop the filter until the engine is turned off. After ten minutes of setting there, gravity causes the loose sediment that is obstructing the filter to settle back to the bottom of the filter. You can then start the engine, and repeat the cycle. If this is the problem, it is only going to get worse until you are stranded somewhere.

Your other option is dropping the tank to inspect the fuel pump, but you said you weren't doing that. You could end up doing both, but I would start with the easier alternative. (Maybe easier...I understand rusted fuel line fittings can make those a PITA.)

 

Sure, and the tank was replaced 3 years ago, the filter less than 2 years ago. I understand the physics you describe. Its actually not really a fuel starvation/pump issue (i think) it seems more like an issue of system malfunction, vacuum on the tank perhaps.
If the tank got that dirty inside in the 3 years since replacement the US has severe fuel quality issues! The old tank was very clean inside when I removed it.
I'll see how it reacts to the filler cap being opened when I turn it off and before trying a restart.
Thank you for the replies, I do my own mechanical repairs, far no outside fingers in the pie.

 

Good thinking. You might search "Evaporative Emission Control System" and study what pops up for Gen1.

 

Update... I believe (I hope) that my problem was bad gas...I've not had the problem since running to a second fill of gas. I don't use the truck as much since Covid so not really a lot of miles, but no change I've made can be called a repair. I'll add to this thread if something changes.
I did not change the fuel filter or drop the tank to look inside. I did add some Berrymans but that is no miracle cure...