vapor lock questions

[outlander]

I've never personally experienced vapor lock so can someone give me symptoms to look for?

Is it a common problem on the renix 4.0?

In the process of trouble shooting is there any way to rule it out as a intermitten driveability problem?

Thanks

Oh and can someone tell me where the fuel pump regulator is located on my 89 xj 4.0?

 

[87manche]

Vapor lock will cause stalling/hard starting in a hot motor.
Basically it's when the fuel "boils" and becomes gaseous, fuel pumps can;t push vapor.
It's highly unlikely in a MPFI system because the pump pressurizes the entire line. As the fuel pressure goes up so does the boiling point.
It's much more common in carberetted systems because the fuel pressures are lower, and you've got a bowl full of gas on top of the motor.
If it were to happen I would imagine it would be most likely after you turn off the motor and it sits hot, heat soaking the injector rail with a combination of pressure bleed off.

 

[outlander]

Thats usually when it happens.

 

[my65289stang]

My 65 mustang vapor locked on me a few times, then I remembered just how close my fuel line ran to my long tube headers. Re-routed the fuel line and no problems since. It feels like you just loose power when it vapor locks, your foot is on the gas but it no longer has any "go."

 

[outlander]

yep....noticed that today while cruising around town,seemed down on power with a hot motor.When I go for a drive with a cold motor it seems to have more power.When it's up to operating temp and I shut it off to go into a store for a few minuets,come back out and start it with a hot engine and it sputters.I drive down the road and it clears up.

Its got me baffled.