87 V10 5.7L TBI.... Difficult hot start... Any clues?

[gwrench3]

Hello guys, need a little help when time permits.
My 87 V10 5.7L TBI doesn't like to restart after its hot. I'll drive a few miles to the gas station, as an example, fill it up in about 5 minutes or so. When I jump back in it cranks fine but just doesn't seem to want to fire up. If I wait about 10 or 15 minutes, it will finally fire up. I'm wondering if there is a "hot start" system that the ECM controls that possibly isn't working? No codes, no cranking issues, no overheating issues, just this hard start issue when hot.
Thanks in advance for any help!

[JohnnyPopper]

I'm dealing with a TBI issue myself...welcome to the club!

From what you stated, it sounds like heat is the factor, as in when things get warm/hot there is an increase in resistance that throws the ECM into what we used to call "chasing it's tail".

By and large, Good Grounding  is that first place to look.

Lucky for you, recently there has been a rash of questions/issues like yours. Look for pics, diagrams for grounding points from VZ and bd.

Keep us posted- we love hearing how you get things to work!

[bd]

The first thing to do is determine whether the fault is related to ignition or fuel supply.  When the symptoms occur, do you hear the telltale 2-second run of the in-tank fuel pump when the ignition is first switched ON?  Be prepared in advance so that when the symptoms occur you can quickly check for an ignition spark while cranking.  Rig up a gauge so that you can constantly monitor the fuel pressure and then drive it to recreate the symptoms.  Is the fuel pressure the typical 11-12 PSI when acting up?  When did you last replace the fuel filter?  Is it due for a tune-up? 

Depending on your responses, there are other checks that can be done roadside at a moment's notice without needing tools other than a clean shop rag and flashlight.

To the best of my knowledge, the fuel management module to which you referred, although sometimes responsible for "random and unexplained" symptoms, is pretty much restricted to 3/4- and 1-ton trucks.

[gwrench3]

Thank you JohnnyPopper for your response. All grounds are good between the engine and the rest of the truck. The only thing that is not stock on the truck is the air cleaner. It has an aftermarket K&N 14" open air cleaner (bought it this way) rather than the stock unit that routes to the front radiator support via a hose. I wonder if that may have something to do with the issue (sucking in hot under-hood air)?
Thank you for the help. I'll have to keep looking for the cause!

Thank you bd for your response. When the symptom occurs, I do hear the fuel pump running for the 2 second interval. I do have spark and the proper fuel pressure when the symptom occurs. Fuel filter is new and tune-up has been completed (plugs, wires, cap, rotor, etc.). I guess the ECM on the 87 1/2 ton TBI truck has no "hot start" provision like a quadrajet carb has. I don't believe the fuel is getting hot since the TBI returns unused fuel back to tank. I wonder if the IAC valve has something to do with this issue? I have followed the procedure to set the IAC, but no change.
Thank you for the help. I'll keep trying to figure this thing out.

[bd]

Drawing hot air directly from the engine compartment can introduce a thermal problem.  When the symptoms occur, can you see fuel emitting from both injectors as you crank the engine?

[Stewart G Griffin]

When have the injectors been changed?   Have they ever been changed?