[DML] Re: Vapor Lock

["content22207" <brobertson@xxxxxxxxxxxx>]

I understand vapor lock to be abnormal sucking of gasseous fuel when
you'd otherwise be sucking liquid fuel. Isn't equipment failure, like
a collapsing pickup hose. Pump, carburetor, whatever is working
normally. It just ends up trying to suck fuel in the wrong form
(fuel's fault, not the device's).

I disagree with David's contention that increasing pressure can cause
abnormal fuel evaporation. Just like freon in the condensor, higher
pressure RAISES its boiling temperature. 

I suspect people often blame a variety of other ills on "vapor lock".
As stated before, except for a short period using K Jetronic on my
DeLo, I've driven properly tuned carbureted vehicles exclusively. Have
never once experienced an inability to suck fuel. My current PRV not
only has its carb 3/4" above an all aluminum engine (which everyone
claims is radiating MORE heat than a cast iron block), but the
compartment has virtually no air flow through it. The fuel filter
rests less than 1/2" above the driver valve cover (versus a cooler,
but less accessible, remote location). My experience driving to Pigeon
Forge was uneventful. Note I am using the same fuel tank with a low
PSI pump in a stock boot. And the fuel line runs adjacent to heater
core lines, versus a cooler route through the frame.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, tobyp@xxxx wrote:
> Hello List - I had a conversation with a DeLorean owner who had 
> driven his car to Pigeon Forge.  On the trip, he had a number of 
> suction hose issues down in the tank, and actually had 
> the "opportunity" to do a little DeLorean "tank diving" alongside the 
> interstate.  He told me that the fuel was so hot in the tank that he 
> felt like it was burning his skin.  Between the hot air blowing on 
> the tank from the radiator, and the fuel being returned to the tank 
> from the engine compartment as part of the recirculation that goes on 
> continuously in the DeLorean, the fuel was heated to a significant 
> degree (pun intended).  Here's the question for the List - Would this 
> phenomenon have any bearing on the discussions about fuel vapor 
> lock?  I know that the book that I have on Bosch fuel injection 
> systems says that tank shape is critical for the K-Jetronic system 
> that we have.  According to the book, the tank must be oriented 
> vertically and should be relatively deep so that there can be good 
> intermix of hot and cool fuel within the tank, in order to avoid 
> temperature stratification. Consider the shape and orientation of the 
> DeLorean fuel tank ...
> 
> Toby Peterson VIN 2248 "Winged1"
> DeLorean Parts Northwest, LLC
> www.delorean-parts.com
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> 
> wrote:
> > Isn't vapor lock a suction problem, not a pressure problem (liquid
> > turning to gas due to lowered evaporation point)? If so, the only
> > place it could possibly happen on a DeLo is inside the tank, which 
> is highly unlikely given the cooling effect of all that fuel.




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