1994 Ranger Splash with 118,000 miles on the clock.

A persistent mystery "stop" is bedeviling my truck. Used as a second vehicle so not used every day it will run just fine for weeks at a time with no adverse signals suggesting a repeating problem.

Then, I will start and run sometimes for 20 miles, sometimes for a half mile and it simply dies. The gas is full, the engine will spin easily on the starter but will not fire.

However, leave it for a half hour and it will start and run perfectly, very infuriating !

It's been in the shop twice trying to track this down, diagnostics shows all okay, fuel pump pressure is okay, fuel line is straight and filter unblocked.

The truck is parked in the open in sunny Florida.

I suspect it may be an electronic component that will intermittently fail, perhaps due to under-hood heat issues but can't figure out how I narrow the search.

Any suggestions, has anybody had this and cured it?

 

Ron will is the guru here and will answer here too, but I think the 94 still has a distributor, there were certain years where the ignition became intermittent, so that needs to be taken of the table.
I don't know if ti was the coil or some other component failing in the ignition.

Ron will ask what engine, so I can answer that, it's 3 litre 4x2.

Is it an auto or manual ?

 

Yes, what engine???, lol, am I that predictable
OK, 3.0l Vulcan

Yes, 3.0l used distributor in 1994, last year for that in Rangers

The TFI module(spark) can act like that but on the 3.0l it was on the rad support so unlikely to be heated up fast

What you will need to do is to get a spray can of Quick Start(ether), and a screw driver
drive truck until it quits
try to restart, if it doesn't, open the hood
open air cleaner, take out filter
Spray Ether into engines air tube, leave filter and top off
Try to start
If it starts and then stalls again fuel pump is most likely issue, you can replace fuel pump Relay, its cheap, first
(yes, a fuel pump can fail in this manner)

If it still doesn't start then Spark is the problem, change TFI module

 

On it like fleas on a dog Ron. Didn't take long for you to answer.

Most people are pretty predicable.

 

It's a five speed manual.

I had another thought on this, isn't there a "kill switch" that operates if the vehicle is flipped during a collision? Could that be cutting in?

My shop guy went over the system thoroughly and all tested good but could a coil be affected by underhood heat?

 

If the truck has never been in an accident then it's unlikely the kill switch is the problem.
If it was in an accident and the kill switch (inertia switch) was reset, then that could be a possibility, kill switches don't reset very well and can cause what you are experiencing.

At any rate, do Ron's either test, it will give you and your mechanic a place to start, either fuel or spark.

Coils are and can be effected by under hood heat, especially if they are old, but the TFI module as Ron suggests can act like that, but at this point it's a guess, the either will determine where to start.

How long have you known your mechanic, is he the type where he thinks he's God and doen't like being told what to do ?
I don't have much faith in guys that can't think outside the box and go beyond what the OBDII reader says what's broken, or in your case, what isn't.