1996 F-150 fuel pump test

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Bill Schwab - 12 Oct 2008 00:55 GMT

Hello all,

I managed to disconnect (without breaking them<g>) things I suspected
might have been the diagnostic connectors mentioned in Haynes, and they
look nothing like the illustrations. Some more searching revealed a
statement that a slightly later vehicle has no fuel pump test lead.

Is the 96 F-150 (2wd 4.9) an OBD-II system? I found a "data link
connector" inside the cab on the right side of the console, and it sure
looks like the standard connector.

Is the idea that OBD-II adds codes for the fuel pump? That would
explain a lot.

My lead theory at present is that I have a bad fuel pump check valve
that lead to cross-filling. That would explain the low pressure
condition and the cross-filling, but I'm not convinced it explains the
leak, which is what grabbed my attention.

Bill

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Jeff Strickland - 12 Oct 2008 01:11 GMT

> Hello all,
>
[quoted text clipped - 4 lines]
>
> Is the 96 F-150 (2wd 4.9) an OBD-II system?

Yes. ALL 1996 Model Year vehicles in the USA are OBD II.

I found a "data link

> connector" inside the cab on the right side of the console, and it sure
> looks like the standard connector.
>
> Is the idea that OBD-II adds codes for the fuel pump? That would explain
> a lot.

The idea is that OBD I put diagnostic stuff all over the place and the
mechanics were charging for the specialized knowledge it took to know where
all of the stuff was hiding, and the equipment it took to get the
information out of the various systems. OBD II, among other things,
standardized the data port location to the left side of the dashboard about
where your left leg rests while driving.

OBD II does not have codes to test stuff, it only has more codes to diagnose
stuff.

> My lead theory at present is that I have a bad fuel pump check valve that
> lead to cross-filling. That would explain the low pressure condition and
> the cross-filling, but I'm not convinced it explains the leak, which is
> what grabbed my attention.
>
> Bill

I _just_ got out from underneath a '94 Ranger that had a fuel vapor smell.
The problem was that the filler hose was cracked in several places where it
connects to the gas tank.

We were getting ready to drop the tank to figure out what to fix, but we
removed the 6 bolts holding the bed on, and fixed the gas tank filler hose
from the top. If your F150 has the hoses at the top, I'd strongly suggest
you buy a torx socket and remove the bed to affect repairs to the tank. Work
on the tank in place, DO NOT drop it.

The Ranger has 6 bolts, the filler hose, and the brake light connector near
the rear bumper. Two guys can easily lift the bed and move it back to expose
the gas tank inlet connections.

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Bill Schwab - 12 Oct 2008 04:23 GMT

Jeff,

> The idea is that OBD I put diagnostic stuff all over the place and the
> mechanics were charging for the specialized knowledge it took to know
> where all of the stuff was hiding, and the equipment it took to get the
> information out of the various systems. OBD II, among other things,
> standardized the data port location to the left side of the dashboard
> about where your left leg rests while driving.

I'll look again, but the connector I found is close to the glove box.

> OBD II does not have codes to test stuff, it only has more codes to
> diagnose stuff.

That would do the job if the codes are specific enough to tell me what
if anything is wrong with the pumps. There are also unused pins on the
connector, and the specs I found say that manufacturers can do what they
want with them. If that is true, it might be that pin I need lurks on
the data connector, but (natch), I can't just short unused pins until I
find it.

> I _just_ got out from underneath a '94 Ranger that had a fuel vapor
> smell. The problem was that the filler hose was cracked in several
[quoted text clipped - 5 lines]
> suggest you buy a torx socket and remove the bed to affect repairs to
> the tank. Work on the tank in place, DO NOT drop it.

Good: I asked about removing the bed in the "F-150 gasoline smell"
thread. Not that it necessarily says anything about the F-150, but was
there anything to stop you had you needed to change a pump? I would
hate to remove the bed and then find that I needed to drop the tank
anyway, though I suspect that would be MUCH easier with the bed out of
the way.

> The Ranger has 6 bolts, the filler hose, and the brake light connector
> near the rear bumper. Two guys can easily lift the bed and move it back
> to expose the gas tank inlet connections.

The cross-filling, if that is what happened, suggests the rear pump is
probably bad. I think. It would probably need to come all the way off.

I can get it _off_ :) Is there any trick to putting it back? If it is
just an eye-ball alignment and bolts to spec, then no big deal (other
than the beer it will cost me to get help).

I am still somewhat stuck for clear diagnostic information. Things that
I can get "now" include a subscription to AllData, and I'm told there is
a relevant Chilton book in town. I have the Ford Shop Manual, but it
puts all the diagnostics off onto another volume. It's worth a look at
Chilton; if it has relevant info, I'll get it. Failing that, or in
parallel, would you go after the additional books from Ford, and/or
subscribe to AllData? The sample vehicles on AllData are not filling me
with unending confidence that it would help this time around. Overall,
it's (at least) not bad, and I would launch at it if I did not already
have the shop manual.

Based on Haynes, I'm either missing the location of the fuel pump
diagnostic pin, missing some critical detail in the text, or the
procedures are simply fantasy for my truck. Since my truck is right at
the end of the book's coverage and is a transition year re OBD, it might
be that the book misses me on this. I have found other short-comings
before. If nothing else, reading Haynes first helps me get more out of
the shop manual.

Bill

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Kevin - 12 Oct 2008 14:01 GMT

>> Hello all,
>>
[quoted text clipped - 45 lines]
> near the rear bumper. Two guys can easily lift the bed and move it
> back to expose the gas tank inlet connections.

sorry but that is not correct. several heavier pkups still did not get
it untill 97. A 96 f250 with a 460 is one. KB

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Jeff Strickland - 12 Oct 2008 16:46 GMT

> sorry but that is not correct. several heavier pkups still did not get
> it untill 97. A 96 f250 with a 460 is one. KB

Unless you can provide a cite that has different information, the OBD II
spec was required to be applied to all cars and light trucks offered for
sale in the USA beginning with the 1996 model year.

<FROM THE SPEC>

Does My Car Have OBD-II?
All cars and light trucks built and sold in the United States after January
1, 1996 were required to be OBD II equipped. In general, this means all 1996
model year cars and light trucks are compliant, even if built in late 1995.

</FROM THE SPEC>

You may be correct that the F350 does not have OBD II, but if so, it is also
not a light truck and not covered by the spec at that time. Since the OP is
asking about an F150, I'll stick with the spec as my data source.

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