On Tue, 08 Nov 2005 16:42:13 -0500, with neither quill nor qualm, Al
A. quickly quoth:
Hi all,
Sort of OT, but my truck, being a 1990 is still made of metal. And
lacking a NG called rec.crafts.metalNOTworking, I thought I might try
here. I also posted to alt.autos.for.pickups, but I almost always get
most excellent advice from RCM.
Anyhow...
I have a 1990 F150 XLT, 2WD, auto trans, 5.0L EFI, A/C, dual fuel
tanks. About 90K miles on the (2nd) engine. In the last week or so, I
Mine's a '90 with 107k on the original engine.
have had a really intermittent problem. When driving at a steady speed
maybe 40-50 mph, the engine would "stumble" almost like it was cutting
out for just a second. It would do this 2 or 3 times, then run fine.
Otherwise, it ran smooth as can be. No "check engine" light. A couple
of days ago, this seemed to progress to happening more often and also
sometimes running very rough at idle, almost like it was trying to
idle way too slowly. Yesterday it got worse, and now will barely idle.
If I do not constantly work the gas pedal, it will stall (in or out of
gear). Now I am getting a check engine light, which goes out once the
speed gets up high enough for it to keep running. Once you are moving,
it runs fine.
I'd give odds that you have the same thing I just repaired. Mine quit
idling in town and I had to give it a bit of gas the 2 days before I
had it properly checked it out. I called Ford and they told me the
throttle body came with a new TPS and was only $237 plus installation.
(~$400 dealer job for an hour's work, FEH!)
I called the junk yard and they had one for $50 which took me about
half an hour to install.I had a dual problem. Mine sprung a leak in
the heater hose bypass tube. Of course, they're factory installed and
no press-in tube is available.
I checked the really simple stuff, air filters, plugs, cap, rotor,
ignition wires, no wires knocked off of sensors, etc. None of that
changed anything. This has the "feel" (whatever that means) of a fuel
delivery problem, but I have no solid reason for saying that. I am an
OK backyard mechanic, but a slightly stupid as to how to diagnose EFI
type problems, or maybe even how to narrow it down.
Any thoughts on anything else to try before I (GASP!) relent and drop
it with my mechanic?
I took mine by the local electronic diagnostic shop (freebie checkup
with a local Entertainment book coupon) and they confirmed that it was
either the throttle positioning switch (which I suspected) or the
throttle position solenoid. Both came with the used throttle body.
I appreciate any and all suggestions.
Between the intake manifold (that big aluminum casting on the
passenger side of the truck) and the plastic/rubber air intake
tubing is the dual-throated throttle body. It is bolted on with 4
bolts and the throttle cable clips onto the top of it. My gasket came
off in one piece so I salvaged that, too. The other connections were
the 2 heater hose bypasses and the intake tubes, 4 wire clamps.
See if you can find a nice one at a wrecking yard. Mine was guaranteed
to work so there was no big deal there.
The throttle body consisted of 2 types of metal, aluminum housing and
steel throttle and hose piping, so we're entirely on topic here.
G'luck!
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