95 t100, 4wd, 3.4l
​​​​​​My truck starts just fine on the first crank when it's cold. The problem is after I warm the truck up, stop, then try to restart it. It starts fine no matter what in warmer weather.

That means it's fine to drive to work. Also fine to take to the grocery store, since it's not far enough to warm up the engine. It's the 5-30 minute stop once the engine is warm that's killing me, it'll pretty much only happen if the temperature is below 45 or so.

I jump in and turn the key. It almost starts then dies if I'm not quick enough on the gas pedal. I usually get it started after much cussing, cranking, and almost starts. I haven't gotten stranded yet but I've gotten worried.

This is not a new problem, it's been going on every winter for a few years. It seems to get a little worse each year though.

I don't really know where to start. Any ideas.

 

Sounds like you should replace your fuel filter. Check your plugs.

 

Something is wrong with the cold start system, I don't have a lot of experience with this engine so take it with a grain of salt.

This means the start up enrichment is off somewhere, either fuel (cold start injector, or timer/temp sensors), or air (iacv).

A simple check for the air is to mark your idle air screw, when it won't start, and back it out a few turns. If it starts and idles the valve isn't opening enough. You will need to figure out why, you don't want to bump the base idle up all the time or you will have other issues.

That is not the typical answer to cold temps starts, usually we go right to the fuel system, so thought I'd add it for once.

 

I've replaced the fuel filter and pump and have had the problem before and after. Same with plugs and wires.

It seems like I have spark and no gas.

 

Second this^^^
We also experience this with out first-gen MoreFunners. It seems to be temp-sensitive. Could be that engine control is getting signal saying the combustion chamber is hot, but in fact it has already cooled down?
I would start with the simple things first - maintenance. Those temp senders and their connections should be inspected and cleaned at least once every 23 years
Clean all down to bare, shiny metal, including the mounting threads both on sender and block make. Make sure there is bare metal to bare metal contact; no teflon tape or insulating sealant.. (On our first-gens, the cold start system gets ground through the mounting thread.)
The truck may also have a fuel pressure-up system that raises fuel pressure during hot starts to counter gas vaporizing in fuel lines.

 

You will always have gas, unless you have a serious issue that would show up even when it is warm out, the primary injection system fires regardless of the temp it only adds the cold start injector to the "mix". In fact the primary injectors get longer pulses with a cold temperature signal as part of the warm up strategy (documented in the tccs book, PDF available with Google searches). This (startup enrichment) functions even above 45°, its goal is to get the system/engine up to operating temperature.

If you are reluctant to fiddle with the idle air screw, the throttle pedal should have a similar effect while cranking.

 

This advice would work for a oldie like a 460 or a 327,But not the 5vz. The tb does not have a idle air screw, Rather it has a type of hydraulic tensioner. For the 5vz from my experience, When it has a hard time starting like that , It normally has to do with fuel delivery. Change your fuel filter, They are 6 bucks from rockauto. And this engine is fuel injected, Their is no carb, So never pump the gas ever on this truck. Replace the fuel filter and go from their. If you have time to ttinker with the beast, Pull off the tb and intake and clean it . clean your maf. If your on a budget of time or money then don't sweat it. Replace the fuel filter then tell us if it fixes it

 

About 4 years ago I had to get a new fuel pump. I swear it had a fuel filter attached and is in the gas tank. I just looked up and saw one of those inline types. That's easy enough to change, so I'll do it.

I've had fuel filters get plugged on mid 80s trucks and they sputtered and shuddered instead of accelerating. This truck doesn't do any of that. It's only a starting issue when the engine is warm and it's cold outside.

Tomorrow is forecast to be warm, I might not be able to check after changing the filter.

 

The filter is inline with the frame. Its easy to replace. .