Re: fuel delivery problems with 1990 F-250, 5.8 L engine, dual tanks&Fuel Delivery module

Usenet Newsreader <usenet247reader@[EMAIL PROTECTED]
> wrote in message
news:491B4998.50503@[EMAIL PROTECTED]
> Ulysses wrote:
> > Usenet Newsreader <usenet247reader@[EMAIL PROTECTED]
> wrote in message
> > news:491B21E0.1020700@[EMAIL PROTECTED]
> >> Mike K wrote:
> >>> "Usenet Newsreader" <usenet247reader@[EMAIL PROTECTED]
> wrote in message
> >>> news:5pSdnSsqs80DuofUnZ2dnUVZ_tXinZ2d@[EMAIL PROTECTED]
> >>>> Had a problem with my F-250.  The rear tank rusted out.  I tried to
> > siphon
> >>>> the fuel out of the rear tank and run off the front tank, but the
front
> >>>> tank fuel pump didn't seem to work.  But the truck ran fine off the
> > rear
> >>>> tank when the tank switch was set to "Rear", and the engine almost
died
> >>>> when set to "Front" - I couldn't hear the front pump whir at all
when
I
> >>>> turned the key when the switch was set at "front" but could hear it
> > whir
> >>>> when set to "rear".
> >>>>
> >>>> So I pulled the rear tank out, took out the fuel pump, tagged the
> > lines,
> >>>> and bagged the pump till I could put a new tank in.  That took a
while
> > due
> >>>> to some family health issues, and when I put it back in, I added
almost
> > 5
> >>>> gallons of fuel and the truck started right up.  It ran for a bit
last
> >>>> night, and then this morning it was hard if not impossible to
start.
> > It
> >>>> felt like it was out of gas.  So I added more from a gas can, and
it
> >>>> finally started up.  I went into the house to get my wallet (to
take
> > the
> >>>> truck up to a gas station to fill it up) and when I got outside it
> > stalled
> >>>> again and won't catch.
> >>>>
> >>>> I wondered if there is a problem with the dual tank selector
switch,
> > and I
> >>>> checked to see if there was a some sort of regulator or in line
> > valving,
> >>>> but there is none.  It is possible that I got the fuel lines
reversed
> > when
> >>>> hooking up the tank?  The truck ran good for a while, but felt like
it
> > ran
> >>>> out of gas.  When I added a bit more, it ran OK but ran for a much
> > shorter
> >>>> time.  If I reversed the fuel lines at the fuel pump on the rear
tank,
> >>>> could this allow the truck to run until it pumped fuel through the
fuel
> >>>> injector rail and then into the front tank?  Could the truck run
> > without
> >>>> the front pump working at all?  There is no three or six-way
valving,
> > so I
> >>>> assume that each tank has a Fuel Delivery Module in it.
> >>>>
> >>>> So do both fuel pumps need to work in order to run the vehicle, or
did
> >>>> something happen to just the rear pump which isn't running even
though
> > it
> >>>> is whirring when I turn the key but don't start the vehicle?
> >>> if the rear tank has been emptied into the front tank it is possible
the
> >>> front pump is bad and leaking through the pump into the tank.
> >>>
> >> The front pump doesn't work at all - there is no whirring noise when
the
> >>   switch is set to "front".  So I take it that there is some
> >> electrically-operated valve in the fuel pump that shuts off when
there
> >> is no power applied to the pump, and that keeps fuel moving out of
and
> >> back into the fuel pump that is working?  So if the rear tank pump is
> >> working properly, but the front fuel pump is corroded and/or not
> >> working, the fuel will take the path of least resistance and go into
the
> >> front tank?
> >>
> >>
> >
> > I think that is what Mike K. is suggesting.  Perhaps if you seal off
the
> > unused pump/fuel line that would prevent it from going where you don't
want
> > it to go.
>
> Not quite sure how to do that - I would need some way to remove the two
> "Y" connectors and replace them with two connectors that remove the
> front tank from the loop.
>
>
> >
> > The first thing I think I would do in your situation is to check the
fuel
> > pressure at the rail.  It should probably be above 30 psi if I
remember
> > correctly.
>
> The pump is pumping fuel down the fuel inlet line into the new fuel
> filter (which I still don't see what that has to do with pumping fuel
> into the front tank from the rear) - it's just not returning to the rear
> tank.  SO I fail to understand what fuel pressure has to do with
anything.
> >
> > Another thing I would do is to check the fuel pump relay which is
probably
> > in a large fuse box under the hood.  On Explorers there is another
relay
> > that can be switched tem****aily to test the relay.  By switch I mean
remove
> > the two relays and put them in each other's place.
>
> This is a 1990 truck and according to the wiring diagrams for the 1990
> F-250, there is only one fuel pump relay and the power from that goes to
> the Intertial Switch, then from there to the Fuel tank Select Switch,
> then to the tanks.  There is no whirring noise when the switch is set to
> the front tank, but there is a whirring noise when the switch is set to
> the rear tank.  There appears to be only ONE fuel pump relay.
>
> What I am wondering (and no one seems to be able to tell me) is if there
> is some sort of a valve in the pump that is turned off that prevents
> fuel from being pumped into a tank that is not being drawn from.  If
> that is the case, the fuel is just being pumped into the tank with the
> least resistance.  I assume that since the front pump doesn't "whir"
> when power is applied to it, that this means it might be so corroded
> from not being used for several years (since the locking gas cap jammed
> up and I didn't want to screw with it - and just used the rear tank) and
> I assume therefore that this corroded pump is the culprit.
>
> Or could the pump in the rear tank have developed problems over the
> summer while it was removed and put into storage (covered in a plastic
> bag and kept from having anything press up against it) and therefore
> some valving in the rear pump be a problem here as well?
>
> After I started the truck up earlier during the week, the fuel pump did
> seem to be making a much louder noise than before.  Could this have been

>   a symptom of something wrong with the rear pump even though the engine
> started and it ran (for a while) with plenty of power before it ran the
> rear tank out of gas?
>
> >
> > You didn't mention anything about checking/replacing the fuel filter
(or
I
> > missed what you said) so with a rusty tank I would think that would be
a
> > high priority.
>
> Not really sure why the fuel filter which filters fuel from the pump
> down to the engine would have anything to do with why the wrong tank is
> being filled, but it was replaced.

I guess I misunderstood what you were asking.  I thought you said the
engine
would die after a short time from lack of fuel.  Determining if you have
enough pressure going the the intake manifold might be a clue as to what
is
wrong.  I did not realize that you were SURE it was going into the other
tank instead of to the intake.