Possible fuel pump or fuel delivery issues

Hi. If your 1998 Ford F-150 starts when the electrical system is cold but fails to start after driving, and you have already replaced the battery, alternator, and solenoid, there are a few additional potential causes to consider: 1. Ignition Switch: The ignition switch may be failing or experiencing heat-related issues. Over time, the switch can develop internal faults that prevent the vehicle from starting when it's hot. Consider having the ignition switch inspected and potentially replaced if necessary. 2. Starter Motor: A faulty starter motor can exhibit symptoms similar to what you're experiencing. When the starter motor gets hot, it may fail to engage and crank the engine. Consider having the starter motor tested to determine if it's functioning correctly. 3. Heat Soak: Heat soak occurs when the heat generated during engine operation affects the electrical components, particularly the starter motor. This can cause the starter motor to become temporarily inoperative until it cools down. Insulating the starter motor or installing a heat shield may help alleviate this issue.

4. Wiring and Connections: Inspect the wiring and connections associated with the starting system. Look for loose, damaged, or corroded wires, connectors, and terminals. Heat can exacerbate electrical issues, so pay particular attention to any wiring or connections that may be affected by engine heat. Repair or replace any damaged wiring or connectors as necessary. 5. Fuel Delivery Issues: While this may not directly relate to the electrical system, fuel delivery problems can cause starting issues after the engine is hot. Check the fuel pump, fuel filter, and fuel injectors for any signs of malfunction. Insufficient fuel pressure or clogged components can hinder the engine's ability to start when hot. It is advisable to have a qualified mechanic perform a thorough diagnostic check to identify the exact cause of the starting issue. They can use specialized tools and equipment to pinpoint the problem and provide appropriate repairs or replacements.

This can be related to a couple of issues, the most common of which are:
1. Fuel delivery problem (e.g. the fuel pump produces too low fuel pressure or the fuel pressure regulator can be shot or the injector(s) may be clogged). When you step on it, it leans out and has no power.
2. Air delivery problem or air metering problem:
- a clog in the air intake (I've once had a mechanic leave a rag in the air filter box and the car wouldn't want to accelerate)
- airflow sensor
- map sensor
- throttle position sensor
3. plus, the searching can be a symptom of a shot idle air control motor (stepper motor), but this won't fix the loss of power so I'd suggest leaving it for later, after the loss of power problem's fixed.

Not unusual for fuel pumps to begin to fail once they are heated up from running. First thing in the morning pump is cool, then as you drive, it heats up and begins to lose pressure. After sitting a 1/2hr-1hr, it may start again and run fine for a short time and start to act up again. Had similar problem and found good fuel pressure when tank and pump cool, but lost pressure once vehicle driven a distance and pump heated up. The hotter the weather, the shorter the distance I could drive. If you can somehow set it up to have fuel pressure checked when it starts to act up, that would certainly help confirm if fuel pressure is the culprit.

When you say that it tries to start but does not turn over - I interpret that to mean that the starter is cranking the engine, but the engine fails to start. Is that correct?
The ignition on these cars occasionally looses a single coil, but is not prone to loosing all ignition on all cylinders at once, so probability indicates that the problem is lack of fuel delivery.
This car is prone to two fuel delivery problems: 1) Failure of the fuel transfer pump that moves fuel from the driver side tank to the passenger side tank where the fuel delivery pump is located. If the car runs out of fuel when the gas gauge registers 1/4 full, and runs again if you add more fuel, this is the problem. 2) Failure of the fuel delivery pump. This is less common, but my wife's '04 330 lost a fuel pump at 80k miles, so it can happen.

Are there any service engine soon lights on associated with this problem?

Possible CTS (Coolant Temperature Sensor) or another sensor giving faulty data for the cool air temperature.

Check spark and gas delivery when cool, below 70 deg. If the spark is not being delivered or the fuel injectors are not delivering fuel at this temperature, it will explain why it doesn't run right until it is warmed up.

Try some staring fluid or a few tablespoons of fuel in the intake manifold at the throttle body.
If the car starts and runs for a few seconds, the fuel delivery has a problem ( like a fuel pump or clogged fuel injector).

If it doesn't start up immediately, then it's a possible spark delivery problem.

That should narrow things down a bit.

could be a fault with the fuel pump. it may be wearing out. check the fuel pressure at delivery. a blocked filter can also do this as its being surged for more fuel not the normal filter this one is on the pump it has larger holes and if you have sludge in the tank this can stop the fuel delivery. . for vacuum leaks spray some carb cleaner around the air lines any change in the engine usually indicates an air leak. also the fuel pressure valve these can all lower or stop fuel pressure.

I would go after the starter, if your starter is weak or ready to seize this will be the symptom, it could also be a fuel delivery issue, if the fuel pump is not working up to pace it wont send deliver fuel.

Good luck.

it's possible that the fuel pump is failing and begins to have problems once it gets hot. i would have someone check fuel pressure once it is warmed up and having the stalling issue.

First thing to do is chg. fuel filter, Now if that has been done and there is no improvement, than do a fuel pressure test, to chk. if fuel pump is putting out the right p.s.i. a few pounds under could indicate pump is getting weak or getting ready to go out, auto parts store can tell you the correct p.s.i. if all that chks. out ok, then you can elimanate it being fuel problem. And its cheep. It could be electrical but it sounds more like a fuel delivery problem to me.