fuel delivery problems with 1990 F-250, 5.8 L engine, dual tanks & Fuel Delivery module
Usenet Newsreader
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?
Mike K
"Usenet Newsreader" <usenet2...@earthlink.net> wrote in message
news:5pSdnSsqs80DuofU...@earthlink.com...
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.
Usenet Newsreader
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?
Ulysses
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.
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.
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 temporaily to test the relay. By switch I mean remove
the two relays and put them in each other's place.
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.
Usenet Newsreader
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 temporaily 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.
Usenet Newsreader
And I should also mention that when I siphoned fuel out of the front
tank (which was almost empty before I started to pull the rear tank in
June) - there was almost as much fuel in the front tank as I had put in
the rear tank. I dropped the rear tank today to make sure I didn't
cross the lines, and that tank was almost empty. And the lines were
connected to the correct fuel pump port. So unless there is a problem
with the rear pump that is clogging the return to the rear pump, or the
front pump is just open and the gas is taking the path of least
resistance, I don't see what fuel pressure or a new fuel filter would
have to do with anything.
sams...@aol.com
wrote:
i THINK , you have three fuel pumps -
one in each tank ( low pressure )
and one high pressure pump which pressurizes
the injectors. the front/back switch
changes only the power ( through a relay )
to the pump in the tank selected.
the low pressure from the pump in the tank selected
moves a valve ( where all four fuel lines are together )
to have both the feed and return lines in use for that
selected tank. there is no electrically move valve
has the fuel filter been replaced?
david
electrons to say:
> Usenet Newsreader wrote:
>> Ulysses wrote:
>>> Usenet Newsreader <usenet2...@earthlink.net> wrote in message
>>> news:491B21E0...@earthlink.net...
>>>> Mike K wrote:
>>>>> "Usenet Newsreader" <usenet2...@earthlink.net> wrote in message
>>>>> news:5pSdnSsqs80DuofU...@earthlink.com...
>>>>>> 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
There should be a shuttle valve (looks like a big can) that switches
between the tanks depending on which in-tank pump is energized. Those
can get clogged up and not switch back and forth. Search the
alt.trucks.ford newsgroup, there was a discussion on this topic a couple
of weeks ago.
Usenet Newsreader
For 1990 trucks there is no such shuttle valve on the frame of the truck
- this is all done inside the fuel pump. That is why I am asking if any
of you know how the fuel pumps control the valving of the gasoline
returning to the tank.
There are at least three separate systems for switching dual tanks. One
is for carbed vehicles that have a fuel pump mounted on the engine -
they obviously don't need gas to return into the tank.
The earlier fuel injected engines did need such valving going both ways
into and out of the tank - and that valving was outside of the tanks.
Later EFI dual-tank set-ups didn't have that separate valving outside of
the tanks - they only switched power from one pump to the other, and the
valving was inside the fuel pump itself. That is the system I have and
that is what I am asking about. So please do not confuse the systems -
I am asking specifically about the later EFI dual tank system with a
check valve inside the pump itself.
Usenet Newsreader
The fuel filter was replaced, and there is no valving in line between
the tanks and the engine. There is just the fuel pump relay, then the
front/rear tank switch - there are supposed to be a check valve in the
tank mounted pump itself.
There si no other fuel pump on the engine. There might have been for
older trucks, but not for the 1990 model.
sams...@aol.com
wrote:
if you know all this why are you asking questions in here?
Usenet Newsreader
and if it was caused by a valve in the fuel pump or something else -
why would a front tank pump that wasn't working allow gas from the rear
pump to full the front tank? I find it hard to believe that one half
the pump in the rear could work yet totally have a valve in the back
(the other half of the pump) not work and pump gas into non-working tank
- makes no sense to me at all.
So I was asking if anyone had similar problems with the same model and
year truck - and all I got was "have you checked for this?" - most of
which wasn't even applicable for my truck. The most bizarre one was the
fuel filter - which makes no sense whatsoever. The engine was getting
fuel because the pump was pumping gas from the rear tank to the fuel
injection rail and through the fuel pump. The fuel was not getting back
to the rear tank - it was going into the front tank for some reason I
can't figure out. That is why I wanted to know if anyone had specific
information about the 1990 pumps and check valves in them.
Ulysses
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.
Ulysses
> 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.
That would work (one relay). The switch probably just switches between the
two electric pumps.
>
> 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.
There is probably a check valve built into the fuel pump if it's anything
like the '91 Explorer pump, which it probably is. It's just a one-way
valve. It doesn't get "turned off" it simply allows fuel to pass one way
only. Unless it's busted.
>
Old Crow
> year truck - and all I got was "have you checked for this?" - most of
> which wasn't even applicable for my truck. The most bizarre one was the
> fuel filter - which makes no sense whatsoever. The engine was getting
> fuel because the pump was pumping gas from the rear tank to the fuel
> injection rail and through the fuel pump. The fuel was not getting back
> to the rear tank - it was going into the front tank for some reason I
> can't figure out. That is why I wanted to know if anyone had specific
> information about the 1990 pumps and check valves in them.
I'm saying that the check valve in the front(inop) pump is bad. Replace the
front pump and all your problems should be solved.
--
Old Crow
'82 FLTC 'Pearl'
'87 FLTC 'Fugly'
'61 F-100
BS#133, SENS, TOMKAT, SLOB#13, MAMBM
Mike K
I found a repair manual, the pump in the tank is not a simple pump but a
fuel control module.
When the fuel pump is shut off, it is suppose to close the fuel return line
to the tank.
I would figure the shut off valve in the front tank is not closing or the
valve in the rear tank is not opening.
The reason to check fuel pressure is to make sure the pressure regulator is
allowing fuel to the return line or if the pressure is too high which might
force the fuel through the front pump into the tank.
Usenet Newsreader
> "Usenet Newsreader" <usenet2...@earthlink.net> wrote in message >
> So I was asking if anyone had similar problems with the same model and
>> year truck - and all I got was "have you checked for this?" - most of
>> which wasn't even applicable for my truck. The most bizarre one was
>> the fuel filter - which makes no sense whatsoever. The engine was
>> getting fuel because the pump was pumping gas from the rear tank to
>> the fuel injection rail and through the fuel pump. The fuel was not
>> getting back to the rear tank - it was going into the front tank for
>> some reason I can't figure out. That is why I wanted to know if
>> anyone had specific information about the 1990 pumps and check valves
>> in them.
>
> I'm saying that the check valve in the front(inop) pump is bad. Replace
> the front pump and all your problems should be solved.
>
>
>
was no problem with it for YEARS? Doesn't the valve stay shut unless
the pump itself is working?
none
I have a 1993, dual tank, F-150. Went to the dealer and discussed this,
plus found the TSBs about the "Fuel Crossover" safety recall on the
websearch in google for Ford TSBs and F-150 TSBs.
On the EFI trucks, the pump and fuel guage selected by the dash switch
is the one that pumps. The recall involved the return line over filling
the tank tht was NOT selected by the dash switch, and the installation
in BOTH pump output lines (the smaller, high pressure line on each pump)
of a redundant anti-back flow valve ($85.00, each!).
I found my preventer valves in the wrecking yard. Not knowing what they
were, I only was charged a buck each. One was from a 1992 F-250.
The TSB covers 1989 through 1993 trucks. Ford had extended this
voluntary recall for 12 years or 150,000 miles, but, many owners
evidently failed to comply!
Link:
http://www.ford-trucks.com/recalls/recall.php/m-FORD/d-F150/y-1993/t-49803
The tools were $7.99 at Harbor Freight Tools. Part Number is P38732 and
includes 3 tools, for all Air Conditioner and fuel lines on most Ford,
GM, and Chrysler vehicles. Please relieve the system pressure and
Negative Battery Cable, before disconnecting any lines!
3...@hotmail.com
Ford to see if your truck was one of them and if it was ever serviced. If
not, you should be able to get it done for free.
NHTSA93V125000 - Check valve malfunction
93S68 - Fuel tank cross-flow condition
01M05 - Fuel cross-flow extended coverage