1996 Explorer - Vapor Lock after warm

[jsickles33]

I've read many posts on here with concerns to what I am experiencing with my wife's 96 V6 explorer, run the truck for about 20-30 mins and then park it, after 10-15 mins go to start and its a crank no start. Have replaced the coolant temp senor, fuel filter, and the fuel pressure regulator. I've believe the fuel rail is getting vapor/air build up. When issue arises I can release the pressure from the fuel rail and she will start right up. I have also tried to remove the gas cap first to see if pressure releases but nothing.

My thoughts at this point is maybe the return line is clogged, in turn allowing fuel to stay in the rail and become cooked by engine heat??

Anyone have any ideas to correct this? Thanks in advance for any help.

 

[jsickles33]

bump for day 2.

 

[Stick4503]

I had a 96 v6 explorer that would do this also. Not sure about releasing the fuel pressure at the rail. I ended up putting a new fuel pump in and never had the problem again. Same thing though, started right up every time no matter how warm it was outside so long as it was the first start up of the day. Run to the store and shut it off and could not get it to restart until the engine cooled.

 

[jsickles33]

Thanks for the reply, I'm hesitant to throw a pump at it as I've read numerous people have done that only to find out it didnt solve the issue, I would think if it was fuel pump related, I wouldnt hear it prime nor would it work after I purged the fuel rail. Someone just suggested to me that it could be the lower intake manifold gasket???? Not sure how it would relate to the fuel supply, anyone have any further insight?

 

[koda2000]

Sounds like a worn out fuel pump to me. How many miles on your tuck and fuel pump? I haven't heard the term "vapor lock" used to describe a fuel delivery issue since the 60's. Back then it was a condition where the fuel line was too close to the exhaust and the fuel would actually boil and the weak mechanical fuel pump could not overcome the air bubble.

 

[jsickles33]

Sounds like a worn out fuel pump to me. How many miles on your tuck and fuel pump? I haven't heard the term "vapor lock" used to describe a fuel delivery issue since the 60's. Back then it was a condition where the fuel line was too close to the exhaust and the fuel would actually boil and the weak mechanical fuel pump could not overcome the air bubble.

About 130K on the truck, I dont know how else to describe it but "vapor lock", if its the pump, why would it work right away as soon as I bleed off the fuel rail, it will also work right away if I cool off the fuel rail with cup of cold water. Its so odd!!! I understand that vapor lock is not a normal term for EFI engines but not sure how else to describe it.

 

[Stick4503]

I hope it is not your pump. However after a week or so of coming up short after random parts and you get around to a new pump, I think you will find that your problem is solved.

 

[96eb96]

About 130K on the truck, I dont know how else to describe it but "vapor lock", if its the pump, why would it work right away as soon as I bleed off the fuel rail, it will also work right away if I cool off the fuel rail with cup of cold water. Its so odd!!! I understand that vapor lock is not a normal term for EFI engines but not sure how else to describe it.

Sounds weird. Try different brands of gas?
I would like to see some pressure tests to implicate/exonerate the pump.

dying pumps can cause cavitation and air, who knows. Pumps can create a lot of heat that way.
Also, try venting the tank, starting it with the gas cap off. Maybe the canister is clogged, forcing vapor into the lines.

 

[koda2000]

Maybe when there is residual pressure in the system it's enough to stop the pump from running? IDK. I'v replaced the fuel pumps in all 6 of my Explorers, Mountaineers and my ST (and one twice due to a defective Aixtex pump). In every case but one, the problem was the fuel pump. The one exception was my '97 Sport (which was still running it's original, '97-dated OE pump with 260k+ on it) so changing that one was a good idea regardless. The '97's problem turned out to be a dirty/loose crank position sensor. Your truck has a fuel pressure regulator on the fuel rail. I don't know what issue that might cause if it was going bad, but bleeding off fuel pressure or cooling the fuel rail might do something to circumvent the problem. Again, IDK for sure.

 

[drdoom]

I would put a fuel pump in that piece.