The webbers hi 2009-07-07 16:22:59
I have this pickup that has a “new” engine it that ran fine in another f150
.. Well, here is the history . The pickup had a blown engine in it (Fuel
injected 302) and sat for around 2 years . I found a good running 302 that
was running fine in the pickup (another 1986) . I got the engines swapped
and it ran fine for the first 150 miles or so .
Well, this is the story now, you can start the thing and run around 2-3
miles and it runs fine. Then it will start to bog down and loose power until
it wants to die . I think it is a fuel problem but am not for sure. It will
eventually die and not want to start .
I have been told that it has a fuel pump in each tank and then a high
pressure one along the frame beside the fuel filter (which I have already
I have put a can of heet in each tank thinking maybe it has water in the
fuel from sitting but it didn’t seem to help .
Any previous experience would greatly be appreciated and/or suggestions and
Tom adkins 2009-07-07 16:23:02
The first step would be to check the fuel pressure. You should have about 35-40 PSI
with the engine running. The spec varies a few pounds either way by vehicle but
anything in that neighborhood is ok. If you see lower than 30, it’s a red flag. If it
looks ok, attach a fuel pressure gauge, tape the gauge to the windshield and drive it
until the problem occurs. If it is fuel related, the pressure will drop off
dramatically. (pump, filter, lines, power feed to the pump, etc) If it quits and the
fuel pressure is ok, then there is another issue.
Have you changed the fuel filter? Possibly a silly question, but it’s easy to
overlook the obvious sometimes. Not that I’ve ever overlooked anything dumb and
Tom 2009-07-07 16:23:36
+it could also be a bad cat, bad coil, bad cap in the ecm, ect ect ect
The webbers hi 2009-07-07 16:25:58
I am wondering if it may be a bad coil , it will run fine when it is cold
but after it warms up , it will start the problem.
I was also wondering if there is a filter screen in the pickup down in the
fuel tanks ?
BTW: yes I did change the big fuel filter that runs along the frame. This is
the only one isn’t it ?
Thanks so the info.,
Tom adkins 2009-07-07 19:18:48
Could be a bad coil, but the fuel pressure test will give you a direction to go in
and is easy to do. Do that first. There are filter screens in the tank but both tanks
would have to have a ton of garbage in them to stop the fuel flow.
The webbers hi 2009-07-07 23:10:00
had a nice rain storm today and just out of curiousity, went out to start
the pickup . It ran weird right off the bat with it being cold and rainy .
Any ideas ?
Another question, should I hear the high pressure fuel pump when I turn the
ignition on ? The high pressure fuel pump is right below the driver’s seat
on the inside of the frame if I am not mistaken.
Thanks for all your help.
Mombu 2009-07-07 23:10:36
You should hear the pump run for about 3 seconds, more or less, before
cranking. Running ratty when cold and wet is USUALLY bad wires, but
can also be bad cap or coil. Do yourself a big favour and whenever you
remove/replace plug/coil wires apply a generous wipe of dialectric
grease on the (well cleaned) tower before reinstalling the wires. On
the plugs too—-.
Posted via a free Usenet account from http://www.teranews.com
Tom adkins 2009-07-07 23:10:39
It sounds like you need a full tune up (plugs, wires, cap, rotor…). Do this first,
then see if your problem still occurs. I’ll bet it will, but you need to do the tune
up before chasing other concerns. Get your fuel pressure gauge ready.
The webbers hi 2009-07-07 23:10:51
I have put in new plugs , wires, dist cap, rotor, air filter,crankcase
filter,fuel filter and my problem is still there.
I think I am still shootin for the fuel pump , but I don’t have a fuel
pressure gauge and don’t know where/how to hook it in.
Tom adkins 2009-07-07 23:11:02
You can usually rent a fuel pressure gauge from your local chain parts store (Auto
Zone, Advance, etc,) If you look closely at the fuel rail, there is a schrader valve
to attach the gauge. It looks like a tire valve. The fuel rail is the chrome tube that
runs along the tops of the injectors. Just screw the hose on to the valve.
If you intend to work on any fuel injected vehicles, a fuel pressure gauge is a
basic troubleshooting tool. This one looks decent: http://tinyurl.com/yrn9nf but I
prefer one with a longer hose so it can be taped to the windshield for driving. Any
fuel system diagnosis without one is just a guess.
The webbers hi 2009-07-07 23:12:34
Went out and drove it today . I have some more info. , if you “get on it”
from a stop, it runs fine until up to about 2500-3000 rpms and then it
starts bogging down . Then when you let off of it and let it run at idle for
a little while and get back into it. It will do the same thing , I am
thinking more and more that it is starving for fuel .
Now, the high pressure fuel pump is on the frame , but which is it ? The one
with all the hoses running out of it or the one right beside the fuel filter
and only one inlet and one outlet ?
Tom adkins 2009-07-07 23:12:59
One inlet,one outlet. The other “thing” is the tank switching valve. I thought you
said you replaced the high pressure pump? GET A FUEL PRESSURE GAUGE and stop guessing!!
The webbers hi 2009-07-08 06:16:00
No, I haven’t replaced the high pressure fuel pump.
If you were a bettin man (maybe you are 🙂 ) , would you lay $ on the high
pressure fuel pump being bad ?
Tom adkins 2009-07-08 06:16:58
Absolutely, since it’s your money that I’m betting. At this point, you don’t even
know for sure if it’s a fuel problem.
Here’s a quick check:
-Lay under the truck with your hand on the pump.
– Have someone turn the key from Off to On (don’t start it).
– You should hear and feel the pump run for about 3 seconds to pressurize the fuel
– If it runs, it’s about a 50% chance that it’s bad and producing low/no pressure.
Also 50% that it’s good and the problem is somewhere else.
Raz, buddy, dude, I don’t know any other way to say it without buying headline space
in your local newspaper- BEG, BORROW, or STEAL A FUEL PRESSURE GAUGE!! You can rent
one from almost any chain auto parts store for a net cost of $0 after you return it.
Happy traveler 2009-07-08 06:18:36
Some people (my kids being a prime example) just HAVE to learn from their
own experience. Why not let him do that?
The webbers hi 2009-07-08 16:02:22
I made a fuel pressure gauge and taped it to the winsheild like you said. I
am running 30lbs at idle and when I romp on it, it runs up to 40 lbs. I
drove a full tank of gas out of this pickup and it didn’t even mess up once
! UNTIL , I switched tanks ! I have a sticky dash switch or the actual valve
that switches the tanks. When the tank ran out, I saw the fuel pressure take
a dive down to 0-5 lbs and then my problem occured. I had to flip the switch
4 or 5 times before I saw the fuel pressure come back up and now it is still
I don’t know whether to replace the valve or just run on one tank all the
Thanks so much for your help .
Tom adkins 2009-07-08 16:02:48
AAHAAA!!! The tank switching valve is bad.(I don’t think I’ve EVER seen a dash switch
fail. It could though.) Those things can cause all sorts of goofy problems. You
really could get lucky with a used one, they don’t really fail often, but when they
do… The best course is, obviously, a new switching valve.
If you can live with one tank, you should bypass it completely.
See how easy that was with the gauge? You could see the problem happen before your
eyes. The 30 at idle and 40 under load is perfect. Keep that tool in your arsenal and
there will never be a fuel pressure question again.
Glad you found the problem Raz, Best of luck to you.
Tom adkins 2009-07-08 16:02:51
You said you “made” a fuel pressure gauge. I’m really curious, how did you do that?
Bruce l. bergm 2009-07-08 16:03:16
I’m not Raz, but even I know the answer: The only tricky part is
getting the male test port for the fuel rail test fitting.
The rest is a simple exercise in plumbing and mechanical assembly
that can be done a bazillion different ways depending on the materials
you have at hand. Myself, I’d go for high pressure rubber fuel line
(as small as possible) and a mechanical bourdon gauge – one with a
diaphragm isolator would be a bonus, so the bourdon tube cracking
can’t make a big fuel leak.
Electric gauges are way too slow to catch transients, like you would
get with air bubbles or a pump that momentarily seizes or loses prime,
or the power supply is intermittent…
—<< Bruce >>–
The webbers hi 2009-07-08 18:35:58
I am a journeyman tool and diemaker by trade and forklift mechanic . I work
in an automotive stamping facility and has access to all types of gauges,
hoses and fittings .
We have our own hose fitting machine so making a high pressure hose was not
a problem .
Then I just took the valve core out of the schrader valve and found a
fitting that would thread on.
Just the profession I am in and now I have another tool that can be used