Re: 1996 Ford Ranger 4 banger engine check engine light
Yes.... wide open throttle at highway speed should deliver the same pressure
as key on engine off.... not sure what it is in your instance but, if you
need, I can check.... usually 40 or so psi but there are those that are
different. If nothing else, we can eliminate this as part of the concern.
Here's the reasoning and an explanation of why a fuel pressure regulator (or
some other means of regulating the pressure) is required. These fuel
injectors are designed to give a particular spray pattern and atomization
size but this ideal condition only happens when the pressure drop across the
injector nozzle is at a predetermined value. When intake manifold vacuum is
high (much vacuum), the fuel pressure is reduced to maintain the ideal
pressure difference. When intake manifold vacuum is low (wide open throttle,
high engine loads), fuel pressure is increased to maintain the desired
pressure drop. Additionally, the PCM knows how much fuel will flow through
the injector at this pressure differential and computes injector on time
using this "known" value. It can learn changes in the fuel delivery, but it
can only compute so far before it decides that something is wrong that it
can't compensate for. At this time, it defaults to preset values and turns
on the CEL.
There are many tests that it would be nice if you had the means to perform
them... as it is, we can try to do those that we can and minimize the pain
in your hip pocket...
"einbit" <email@example.com> wrote in message
> No worries Jim,
> last night I change all the rubber vacuum hoses I could get to, there is
> one surrounded by the intake maniflod an the PCV that I could not get to I
> will call Ford for the PCV hose and also a new groumet for the PCV, since
> it looks premolded. I did recheck the air intake ducts and even ran the
> engine and sprayed carb cleaner at all of the joints, listen to hear if
> the engine idle up or down. the engine ran smooth.
> there has been no major work on the enigne. It is due for a new timing
> belt. the only scan tool I have is a Actron OBDII Auto scanner CP9135, I
> have been looking for PC software that gets more involved at the vehicles
> performace, but have not found any bellow 500.00.
> the truck has 166,000 miles on it.
> I do have a CP7818 Fuel Pressure gage I can also make long hose assembly
> for High Presure teflon so I can see what its does under demand, if the
> fuel pump is out putting good strong volume then the pressure should be
> sorry for the long rambles