: Hi Everyone,
: I'm having what I believe is serious vapor lock
: problems with my 1979 Dodge D150 truck with
: 318 V8 and air conditioning. I've owned it
: for 3-1/2 years now. Anytime the outside air
: temp is over 80ºF it has this problem. It
: just seems to run out of fuel on heavy
: throttle, or anytime when just driving
: around town. If I back off on the throttle
: and wait it will start to run again as the
: fuel catches up. If I hold the throttle to
: the floor it will surge and jerk as little
: pulses of fuel make its way into the
: carburetor.
:
: Has todays fuel changed this much to have such
: a bad vapor lock problem? Has anyone else
: experienced such problems with their
: vehicles? I'm here in Minnesota, many of you
: are in warmer climates.
:
: I rebuilt the engine 2 years ago looking for
: any problems but found nothing except a worn
: timing chain. The truck has a replacement
: aftermarket radiator in it. I had it checked
: at a radiator shop after I could not find
: anything wrong with the radiator, they told
: me it is good. However the temperature gauge
: reads way high on warm days too. This could
: be because of the vapor lock problem and
: running lean on fuel when traveling down the
: highway. Lean fuel condition will make more
: heat, correct?
:
: This truck has no vapor/fuel return line (from
: engine compartment to fuel tank) like they
: added in the 1980's. I would like to add one
: except this truck has factory dual fuel
: tanks and adding a return line would require
: a expensive 6-way fuel selector valve in
: place of the 3-way valve already on it. I
: checked for rusted or leaking suction line
: but find no problem. Last year I did find
: the supply hose connected to the fuel pump
: was cracked and leaking air, however with
: this it would not run at heavy throttle in
: cool weather either.
:
: This problem has existed all 3+ years I owned
: the truck. Same symptoms both before and
: after engine rebuild. Yes, I installed a new
: fuel pump too, plus tried a different one
: last week, still same vapor lock problem.
:
: The steel fuel line runs kind of close to the
: exhaust system up near the engine, I added
: some insulation over the fuel line in this
: areas to keep exhaust heat away from the
: fuel line. It was cloudy and cooler today so
: only once did I notice it running short of
: fuel and this was in town after I had shut
: off the enigne and restarted and drove away
: 5 minutes later.
:
: Oh yea, this problem is after the engine is
: thoroughly warmed up. Never with a cold /
: cool enigne or on a cool day.
:
: I did find service bulletins for early 1980's
: thru 87 or so vintage Chryco cars and trucks
: about a driveability improvement package
: that consisted of installing a electric
: in-tank fuel pump in addition to the
: mechanical fuel pump. Also found a bulletin
: for a truck to add a big fancy vapor
: separator in the engine compartment by the
: fuel pump.
:
: Perhaps my problem is because of changes in
: fuel during the past 20 years??? Any ideas
: appreciated.