Hello,

I have been having an issue with what may seem like “vapor lock”. This issue happens most frequently when I have driven only a short distance, maybe 5 to 10 minutes. I’ll shut the truck off and when trying to restart after only running into the store for a few minutes my Ranger will not start, just cranks. I found my when I hit the fuel line test port’s schrader valve I will hear air escape and then the truck will start. When the truck sits for hours like when I’m at work or coming out to the truck after sitting over night I don’t have any issues starting it. I have replaced the fuel pump, FPR, fuel injectors and fuel filter about a year ago. Any help or advice would greatly be appreciated, thank you.

1994 Ford Ranger 3.0L M/T

 

The fuel system should hold 20psi pressure with key off so can't do vapor lock, but if pressure is dropping to 0psi then fuel could vaporize in the fuel rail in a hot engine bay, but it would have to be pretty hot, so more of a summer issue

But you have pressure if air/fuel came out of pressure test port, so an odd one

First test if you have WOT(wide open throttle)
Put a stick against the seat to pressure down gas pedal all the way
Go to engine bay and see if you can manually open the throttle more, if not all is well,
If so then Google: Ford Ranger throttle can mod
Easy fix

Next time hot engine doesn't start, do "Clear Flooded Engine"
Key on
Press Gas pedal down to the floor and hold it down, this turns OFF fuel injectors
Crank engine
It should not start, no fuel, if it starts then fuel was leaking in from an injector and flooding out the engine after sitting a few minutes, if it sits longer the fuel evaporates so not an issue


I use Clear flooded Engine in my 1994 4.0l every morning, it has 400k
I crank the engine for a count of 5 before I release the gas pedal so it starts up with oil already circulated

 

Thank you RonD.

I’ll check out the things you mentioned. I’m also going to monitor fuel pressure to see if I’m losing fuel pressure after shutting the engine down. When I tap the shrader valve it is usually accompanied by fuel just dribbling out and what sounds like air escaping behind it. In my experience there should be almost a burst of fuel from pressure when the schrader valve is tapped.

 

Yes, 1986 to 1997 Rangers used 35psi running pressure and that should hold at 20+psi after key off
Although its not uncommon for fuel pump's internal check valve to leak fuel back into the tank after it gets older
That's not a big deal usually, as Key On runs the fuel pump for 2 seconds which gives the system 10psi which is usually enough to start, when RPMs are above 400 pump comes on full time to get the 35psi

But if fuel is leaking into the engine it floods it out, which prevents easy re-start