On Wed, 20 Jul 2005 07:05:21 -0700, email@example.com
>I'm the original owner of a '94 Bronco, 351 cid with 125,000 miles. It
>has a new cooling system - radiator, water pump, hoses, etc. (no
>leaks of water, oil or other fluids)
>During the extreme heat ( 110 - 117 degrees in Las Vegas) the truck
>shuts down. It acts like what we used to call "vapor lock - boiling
>gas". The truck seems to starve for gas and air. It runs irradically
>[sp] when I do get it started after a short cool down to get it home.
>It will drive fine most of the day until the heat gets extreme and
>this only happens in the summer months. (past three summers). The rest
>of the year every thing is fine with no trouble what so ever.
>Any ideas would be helpful!
Vapor lock is not a likely problem. Be sure you have a good
fuel filter. If the fuel pump and regulator are keeping the
pressure in specs, it won't vapor lock at the pressure
modern EFI systems operate. You can buy a fuel pressure
test guage from places like Pep Boys for about $40. It will
work on most current EFI systems.
The first thing I would try is a new ignition control
module. Yours should be mounted on the left fender apron
near the rear. It is mounted in a heat sink which can cool
it relatively quickly compared to the old location on the
distributor. A bad module will not necessarily test bad.
Any time it is running, it will likely test good. When you
install the new one, be sure to use a good thermal paste or
grease or, in years past, called heat sink grease to help it
cool and greaty extend it's life. It is probably a fair
idea to replace the grease every couple of years if you find
yourself with nothing better to do some afternoon while
waiting for the bars to open. Many electronics stores and
computer shops have the stuff since it is used to attacth
the cooling fan to the CPU in computers and other similar
If the fuel pressure tests OK and you have replaced the ICM,
your next step should be to get a complete diagnostic scan.
Many independant shops have the equipment to do this but,
the best equipment is, sorry to say, in the hands of a Ford
dealer. That does not mean a particular tech will be able
to correctly interpret the data or, that the fault will show
up in any particular diagnostic session. Intermittent is
the longest four letter word in the English language.